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PRODUCTIV

SOIL

BY

W.W,WI

I O

AGR1C. DEPT.

" The first farmer was the first man, and all historic
nobility rests on possession and use of land."

— EMERSON.

LIPPINCOTT'S

FARM MANUALS

EDITED BY

KARY C. DAVIS, PH.D.

PROFESSOR OF AGRICULTURE, KNAPP SCHOOL OF COUNTRY LIFE, GEORGE PEABODY

COLLEGE FOR TEACHERS, NASHVILLE, TENNESSEE; AUTHOR OF

PRODUCTIVE FARMING, ETC.

PRODUCTIVE SOILS

BY WILBERT WALTER WEIR, M.S.

FORMERLY ASSISTANT PROFESSOR OF SOILS, FIELD MAN, WISCONSIN STATE SOILS

LABORATORY AND SOIL EXTENSION SERVICE, COLLEGE OF AGRICULTURE,

UNIVERSITY OF WISCONSIN

LiPPiNCOTT's FARM MANUALS

Edited by K. C DAVIS, Ph.D.

KNAPP SCHOOL OF COUNTRY LIFE, NASHVILLE, TENN.

PRODUCTIVE SWINE HUSBANDRY 1915

BY GEORGE E. DAY, B.S.A.
PRODUCTIVE POULTRY HUSBANDRY 1919

BY HARRY R LEWIS, B.S.
PRODUCTIVE HORSE HUSBANDRY 1920

BY CARL W. GAY, D.V.M., B.S.A.
PRODUCTIVE ORCHARDING 1917

BY FRED C. SEARS, M.S.
PRODUCTIVE VEGETABLE GROWING 1918

BY JOHN W. LLOYD, M.S.A.

PRODUCTIVE FEEDING of FARM ANIMALS 1916
BY F. W. WOLL, PH.D.

COMMON DISEASES OF FARM ANIMALS 1919

BY R. A. CRAIG, D.V.M.
PRODUCTIVE FARM CROPS 1918

BY E. G. MONTGOMERY, M.A.
PRODUCTIVE BEE KEEPING 1918

BY FRANK C. PELLETT

PRODUCTIVE DAIRYING 1919

BY R. M. WASHBURN, M.S.A.

INJURIOUS INSECTS AND USEFUL BIRDS 1918
BY F. L. WASHBURN, M.A.

PRODUCTIVE SHEEP HUSBANDRY 1918
BY WALTER C. COFFEY, M.S.

LIPPINCOTT'S COLLEGE TEXTS

SOIL PHYSICS AND MANAGEMENT 1919 -
BY J. G. MOSIER, B.S., A. F. GUSTAFSON, M.S.

FARM LIFE TEXT SERIES

APPLIED ECONOMIC BOTANY 1919

BY MELVILLE T. COOK, PH.D.
PRODUCTIVE PLANT HUSBANDRY 1918

BY KARY C. DAVIS

HORTICULTURE FOR HIGH SCHOOLS 1919
BY KARY C. DAVIS

LABORATORY MANUALS AND NOTEBOOKS

ON THE FOLLOWING SUBJECTS
SOILS, BY J. F. EASTMAN and K. C. DAVIS "is

POULTRY, BY H. R. LEWIS wis
DAIRYING, BY E. L. ANTHONY un

FEEDING, BY F. W. WOLL "i?
FARM CROPS, BY F. W. LATHROP "20

LiPPiNCOTT's FARM MANUALS

EDITED BY K. C. DAVIS, PH.D.

PRODUCTIVE SOILS

THE FUNDAMENTALS OF SUCCESSFUL SOIL

MANAGEMENT AND PROFITABLE CROP

PRODUCTION

BY

WILBERT WALTER WEIR, M.S.

FORMERLY ASSISTANT PROFESSOR OF SOILS, FIELD MAN, WISCONSIN STATE SOILS

LABORATORY AND SOIL EXTENSION SERVICE, COLLEGE OF AGRICULTURE,

UNIVERSITY OF WISCONSIN

235 ILLUSTRATIONS IN THE TEXT

"If vain our toil,
We ought to blame the culture, not the soil."

POPE — Essay on Man

PHILADELPHIA & LONDON
J. B. LIPPINCOTT COMPANY

COPYRIGHT, IQ2O, BY J. B. LIPPINCOTT COMPANY

Electrueyped and Printed by J. B. Lippincolt Company
At the Washington Square Press, Philadelphia, U.S.A.

DEDICATED
TO THE INTERESTS OF BETTER FARMING

"A SOWER WENT OUT TO SOW HIS SEEDJ AND AS HE SOWED, SOME FELL BY THE
WAYSIDE; AND IT WAS TRODDEN DOWN, AND THE FOWLS OF THE AIR DEVOURED IT.
AND SOME FELL UPON A ROCK; AND AS SOON AS IT WAS SPRUNG UP, IT WITHERED

AWAY, BECAUSE IT LACKED MOISTURE. AND SOME FELL AMONG THORNS J AND
THE THORNS SPRANG UP WITH IT, AND CHOKED IT. AND OTHER FELL ON GOOD

433002

PREFACE

THIS book is designed primarily to meet a growing demand for
definite, practical and complete information concerning soils and
profitable crop production. This, therefore, is a book of fundamen-
tals, and hence applicable to a wide range of country. The basic
facts concerning soils, and the fundamental principles of success-
ful soil management are essentially the same everywhere, but the
method of application must necessarily vary because of different
climatic conditions.

This text represents an extensive experience on the part of the
author — from practical farming before and after college gradua-
tion to university teaching and Extension Service. It is hoped
that the facts and principles herein presented will lead the prac-
tical farmer and the student into a broad field of interesting and
profitable knowledge.

To one who is familiar with the crumbling of the soil as it moves
over the moldboard, these chapters will not be entirely new and
strange, but will present things both new and old. It is the hope
that the new and the old are presented in such a way as to elim-
inate the difficulty too often experienced by searchers after the
fundamentals — namely, the failure to place the facts and prin-
ciples in their true relation to successful farm practices— a dif-
ficulty which has been the result of a lack of proper organization
and correlation of the subject matter.

In his teaching of many hundreds of farm boys as well as prac-
tical farmers, the author has had the opportunity to test out vaii-
ous methods of instruction and arrangement and correlation of the
subject matter. Actual results have been the only guide in deter-
mining the best plan. Even after this course of study was fully
completed it was thoroughly tried out on several classes before it
was put into publication. The plan of the book may readily be
seen by studying the Contents.

Special effort has been made to present the subject in as simple
a form as possible while making it complete and authorita-
tively correct.

It is impossible to mention the many original papers, "research
data and other agricultural literature consulted.

vii

viii PREFACE

This course of study in the complete edition is designed to
give it wide adaptation, to wit :

(a) It may serve as a farmers' ready reference, or as a prac-
tical guide in successful soil management.

(6) In college short courses, and normals, the whole course as
it is planned may be given. The object of each student should
be to master the fundamentals.

(c) In college long courses, this text in the hand of the first- or
second-year student may supply him with the fundamentals, leav-
ing the lecture hour free to the instructor for elaboration, for
application of facts and principles to local conditions, and for the
presentation and discussion of experimental and research data.

The subject of Soil Management and Crop Production is truly
large enough and of sufficient importance to be given a place in
every agricultural curriculum. This subject should precede or may
be given at the same time as the allied subject, Farm Crops. The
latter subject could then be made a study, not so much of soils in
relation to growing the crops, but rather of crop characteristics,
crop importance, types, varieties, judging of grains, seed pro-
duction, special cultural methods, harvesting, and care of crops
and grains.

At the close of each chapter suggestions are offered for demon-,
strations, laboratory exercises, and for home experiments and
projects. Many questions and practical problems are also given.

The author wishes to express his appreciation to Prof. E. Truog
of the Department of Soils, and to Prof. J. A. James of the Depart-
ment of Agricultural Education, University of Wisconsin, for care-
ful reading and approval of the manuscript; to Prof. E. R. Jones,
University of Wisconsin, for verifying the chapters on water rela-
tions and drainage; to Prof. C. F. Marbut, in charge of soil survey,
Bureau of Soils, United States Department of Agriculture, for
valuable suggestions concerning soil types and for approval of
that part of Chapter II relating to that subject.

W. W. WEIR.
MADISON, Wis.
January, 1920

ACKNOWLEDGMENTS OF ILLUSTRATIONS

Yerkes Observatory — Fig. 1. M. C. Ford, Bowling Green, Ky.
—Figs. 4, 34 and 199. The Macmillan Company— Figs. 13 and 43.
L. W. Brown, Photographer, U. W. — Fig. 30 and frontispiece.
American Chemical Company, Boston — Figs. 32, 142 and 169.
Janesville Machine Company, Janesville,Wis. — Figs. 66, 68, 69, 71,
74, 85, 87, 92, 106, 107, 112, 143, 210 and 213. Deere and Company,
Moline, 111. — Figs. 73 and 88. Moline Plow Company, Moline,
111.— Fig. 160. D. S. Bullock, U. W.— Fig. 144. Allis-Chalmers
Mfg. Co., Milwaukee — Fig. 155. Rockfield Products Company,
Milwaukee — Fig. 154. Jeffrey Mfg. Company, Columbus, Ohio —
Fig. 157. J. S. Donald, Mt. Horeb, Wis.— Fig. 159. Mark W. Potter,
Belhaven, N. C.— Figs. 195, 196 and 204. Mosier and Gustafson,
authors of Soil Physics and Management — Figs. 18, 64, 67, 80,
93, 98. John W. Lloyd, author Productive Vegetable Garden-
ing— Fig. 95. Kary C. Davis, author Productive Plant Hus-
bandry—Fig. 93. U. S. Dept. of Agriculture — Figs. 170 to
187, inclusive.

CONTENTS

SOILS, THEIR ORIGIN AND CLASSIFICATION
CHAPTER PAGE

INTRODUCTION ............................................ 1

I. THE SOIL AND ITS ORIGIN ................................. 5

1. Soil Defined. 2. Soil is Forming from Rock all the Time.

3. The Weathering Agents: (a) Heat and cold, (6) frost, (c)
wind, (d) ice, (e) water, (/) gases; aided by other forces of
nature and by plants and animals. 4. Soil Formation Is a
Complex and Slow Process. 5. Most Soils are Carried Away
or Moved After They Form. 6. Soil of Many Kinds.

II. SOIL COMPOSITION, CLASSES AND TYPES .................... 11

1. Common Meanings of Soil and Subsoil. 2. The Compo-
sition of Soil: (a) Mineral particles — sand, silt, clay — from
rock, (b) Organic matter — remains of plants. 3. Soil a
Complex Medium for Plant Growth : (a) Sand, silt, clay con-
stitute the framework — and contains : (6) water (moisture) ;
(c) soil organisms; (d) air; (e) salts in greater or less amounts.

4. Soil Classification: (a) On the basis of texture (grouped
into classes) : sand, fine sand, sandy loam, fine sandy loam,
loam, slit loam, clay loam and clay, (b) On the basis of mode
of formation: residual, cumulose, alluvial, glacial, marine,
lacustrine, loess and colluvial. (c) On the basis of types
(grouped into series): Dunkirk sand, Genesee loam, Knox
silt loam, Cecil loam, etc., as types.

SOILS FROM A CHEMICAL POINT OF VIEW

III. CHEMICAL COMPOSITION OF SOILS AND ITS RELATION TO PLANTS

AND ANIMALS ..... .................................. 29

1. Soil Materials are Composed of Elements. 2. Chemical
Composition of Soils. 3. The Fertilizing Elements — Nitro-
gen, Phosphorus and Potassium. 4. The Supply of the
Important Elements in Soils not Large. 5. Chemical Com-
position of Soils Influences Plant Growth. 6. Crops
Require Ten Elements— C, H, O, P, K, N, S, Ca, Fe, Mg.
7. Sources of Elements Plants Require: (a) The soil —
nitrogen and mineral elements; (b) The soil water — oxygen
and hydrogen; (c) The air — carbon and oxygen. 8. Ash of
Animal Body is "Dust" of the Earth. 9. The Great Work
of Plants and the Farmer's Business.

IV. How ROCKS AND CLIMATE AFFECT SOILS ................... 39

1. Rocks of Many Kinds, and They Undergo Changes.

2. A Rock is an Aggregate of Mineral Particles. 3. Rock
Minerals the Sources of Mineral Plant-food Elements.
4. The Relation Between the Presence of Particles of Rock
Minerals and the Richness of Soils. 5. Products of Rock
Weathering: (a) Sand, silt, clay — breaking-up products;
(6) True clay (kaolin), (c) Carbonate of lime, (d) Salts.
6. Different Soils from Different Rocks. 7. The Effect of
Climate on Soils: (a) Soils in humid regions are leached.
(6) Alkali soils — formed in dry regions, (c) Much organic

xi

xii CONTENTS

CHAPTER PAGE

matter in soils in cool, moist regions, (d) Deficient organic

matter in soils in warm, moist regions, (e) Sour or acid soils
found in humid regions.

SOIL AND PLANT RELATIONS

V. SOIL AN IMPORTANT FACTOR AFFECTING PLANT GROWTH 47

1. Conditions Surrounding Plants Must be Favorable.

2. Three Periods of Life History of Plant Passed in Contact
with the Soil. 3. The Germination Period : (a) Life in seed
strives for existence. (6) Requirements — moisture, oxygen,
favorable temperature and good tilth, (c) Tilth, good tilth,
poor tilth defined, (d) Absorption of water by seeds influ-
enced by contact between soil and seed, moisture, warmth
and presence of salts. 4. The Vegetative or Growing Period :
(a) Period of greatest activity. (6) Conditions and require-
ments, (c) Full meaning and importance of good tilth,
factors affecting development, (d) Availability of plant-food
elements, (e) Special function of the plant-food elements.
5. The Fruition Period.

VI. CROPS AS FEEDERS ON THE PLANT-FOOD ELEMENTS IN THE SOIL 61
1. Soil Particles are not Plant Foods. 2. Amount of Ele-
ments Removed by Harvested Crops. 3. Some Facts Con-
cerning the Feeding of Crops: (a) Most of phosphorus goes
into grain, and potassium into stalk and straw. (6) All
plants do not take the same amounts of the elements, (c)
Alfalfa a " heavy feeder." (d) Timothy is not a "soil rob-
ber." (e} Some plants have strong feeding powers. (/)
Barley requires a richer soil than oats. (#) Fertilizer needs
best determined by tests. 4. Amount of Plant-food Ele-
ments Removed by Fruit Crops. 5. Supply of Nitrogen,
Phosphorus and Potassium in Soils: (a) Supply varies in
different soils. (6) Per cent vs. pounds of plant-food ele-
ments in soils, (c) Peat soils are usually deficient in the
mineral elements (K and P). (d) Peat lands are sometimes
deceptively advertised. (e) Subsoils contain plant-food
elements.

CROP PRODUCTION

VII. CROP PRODUCTION AND SOIL FERTILITY 75

1. Factors in Successful Crop Production: (a) Fertile soil,
determined by moisture in soil, air in soil, good tilth, pres-
ence of helpful organisms, plant-food elements, absence of
harmful agents. (6) Good seed: high test, adaptability,
purity, disease resistant, high yielding, etc. (c) Favorable
temperature, (d) Light: some crops require much light,
some less; shading a factor in weed-killing; weeds may shade
crops; one crop may deprive another of light, (e) Protection
from injury: proper fencing, spraying, treating seed, drain-
age, etc. 2. Soil Fertility (Defined). 3. Factors which
Determine Soil Fertility Same as Those Which Make a Fertile
Soil. 4. Soil Exhaustion: (a) Illustrated by draft upon the
phosphorus supply. (6) Soil exhaustion usually the result
of: the removal of organic matter; the removal of available
plant-food elements; the removal of carbonate of lime;
improper tillage. 5. Most Soils can be Improved in
Some Way.

CONTENTS xiii

FACTORS DETERMINING SOIL FERTILITY

VIII. SOIL WATER AND ITS RELATION TO SOIL FERTILITY 89

1. Why Plants Require Water. 2. Crops Require Much
Water. 3. Water Requirements of Some Crops — Based on
Dry Matter Produced. 4. Water Commonly Limits Crop
Production. 5. Forms of Soil Water — Gravitational, Capil-
lary and Hygroscopic. 6. Capillary Water of Most Import-
ance: Held by soils in form of films around the soil particles,
in organic matter, and within soil crumbs. 7. Movements
of Water in Soils: Percolation, seepage, capillary rise of
water. 8. Water-holding Capacity of Soils. 9. Moisture .
Conservation and Control — (a) Lessen surface run-off by
aiding soils to trap water. (fr) Increase water-holding
capacity by adding organic matter, (c) Aid capillary rise of
moisture by compacting the seed bed. (d) Lessen surface
evaporation by developing a soil mulch, (e) Conserve mois-
ture by killing weeds.

IX. LAND DRAINAGE AND IRRIGATION 109

1. Too Much Water is Harmful. 2. Benefits of Proper
Drainage. 3. How Drainage is Accomplished: (a) Surface
drainage. (6) Subsurface drainage, (c) Vertical drainage.
(d) Combined methods. 4. Tile Drainage: (a) Drain tile
and how they are laid. (&) Distance to lay lines of tile, (c)
Systems of tile drainage — natural, gridiron, herring-bone
and combination of systems, (d) Cost and benefits of tile
drainage. 5. Drainage by Means of Pumps. 6. Irrigation
Defined : (a) Objects of irrigation and how irrigation water
is secured. (6) How irrigation water is applied — flooding,
furrow irrigation, spray irrigation and sub-irrigation, (c)
Irrigated farms require good management. (d) Many
irrigated lands need drainage, (e) Profits in irrigation
farming. (/) Irrigation an art of antiquity.

X. TILTH AND TILLAGE 135

1. Tilth and Tillage in General: (a) Factors determining
development of good tilth. (6) Tillage tools are many, (c)
Objects and principles governing tillage. 2. Preparing the
Seed Bed: (a) Plows and plowing, (fr) Subsoiling, deep till-
ing and dynamiting soils, (c) Harrows and harrowing, (d)
Rollers, plankers and clod crushers. 3. Seeding and Plant-
ing: (a) Good firm seed bed favors planting. (6) Drills vs.
broadcast grain seeders, (c) When discing is better than
plowing. (d) Listing. 4. Cultivation and Intertillage :
(a) Why crops are cultivated. (6) Cultivators and their
adaptability, (c) When and how to cultivate.

XI. SOIL ORGANISMS IN RELATION TO SOIL FERTILITY 171

1. Organisms of Decomposition: (a) No crops without de-
cay. (6) Organisms cause decay of organic matter, (c) Decay
of organic matter aids decay of mineral particles, (d) Some
fertilizers would be valueless without decay. 2. Bacteria
Which Cause Nitrification: (a) Importance of nitrification.
(6) Catch and cover crops conserve nitrates, (c) Nitrifica-
tion results in loss of organic matter. 3. Bacteria which Fix
Atmospheric Nitrogen in Soils: (a) Two groups of nitrogen-
fixing bacteria. (6) Amount of nitrogen gathered per acre,
(c) How nodule bacteria work, (d) How the growing of
legumes improves soils, (e) Soil inoculation and methods.
(f) Conditions favoring soil bacteria.

xiv CONTENTS

XII. NITROGEN, PHOSPHORUS AND POTASSIUM IN RELATION TO SOIL

FERTILITY 187

1. Fertilization and the Theory of Fertilizers. 2. Green ,
manuring: (a) Green manuring and its benefits. (6) Crops
for green manuring — legumes best, (c) Plowing under the
crop — when, how and for what crops, (d) Feeding vs. plow-
ing under the crop, (e) Some hints on green manuring.

3. Commercial Fertilizers: (a) Four classes of commercial
fertilizers. (6) Nitrogen fertilizers and their value. Legumes
to solve nitrogen problem, (c) Phosphate or phosphorus
fertilizers and their uses, (d) Potash or potassium fertil-
izers and their value, (e) Mixed fertilizers. (/) Concerning
commercial fertilizers in general, (g) Soils and crops deter-
mine kind to use. (A) Home mixing of fertilizers, (i) How
commercial fertilizers may be applied. (j) Lasting effect of
fertilizers. 4. Manure as a Fertilizer: (a) Some facts about
manure: (1) Fertilizing value about $2.34 per ton. (2)
Manures differ in fertilizing value. (3) Feeding affects
value of manure. (4) Amount of manure produced by farm
animals. (5) Liquid portion of manure valuable. (6) Some
practical pointers on use and care of manure: (1) Manure
has three-fold value. (2) Manure a quick fertilizer. (3)
Stall manure better than open-yard manure. (4) Hints on
storing manure. (5) Light applications better than heavy
applications. (6) Plowing under vs. discing in manure.
(7) Applying manure to clover fields. (8) Manure not a
perfect fertilizer.

XIII. SOIL ACIDITY AND LIMING IN RELATION TO SOIL FERTILITY .... 229
1. Soil Acidity Explained. 2. Soil Acidity Lowers Soil
Fertility (Productiveness). 3. The Meaning of Liming.

4. How Liming Improves Acid Soils: (a) Available calcium
is added for clover and alfalfa. (6) Absence of acidity favors
the helpful soil organisms, (c) Plant-food elements are
rendered more available, (d) Greater returns are secured
from fertilization, (e) Lime tends to improve tilth on
heavy soils. (/) Helps to control malnutrition diseases of
truck crops, (g) Weeds may be better controlled. 5. Crops
Benefited by Liming When Grown on Acid Soils. 6. Crops
Which Tolerate Acidity. 7. How Acid Soils May be Deter-
mined: (a) By the use of blue litmus paper; (6) by chemical
tests; (c) by alfalfa and clover failures; (d} by the growth of
certain plants. 8. Low Wet Lands not Necessarily Acid.
9. How Soils Become Acid— Extent of Acid Soils. 10. The
Nature of Soil Acidity. 11. Kinds of Agricultural Lime.
12. Comparative Value of Agricultural Limes — the Best to
Use. 13. Amount of Lime to Apply. 14. When, How and
How Often to Apply Lime. 15. Deep Plowing Cannot be
Substituted for Liming. 16. Soils Derived from Lime-
stone May Become Acid. 17. Soil Fertility is Regulated
Through Liming.

XIV. HARMFUL AGENTS IN SOILS AFFECTING FERTILITY 255

1. Worms and Insects in Soils May Destroy Crops. 2.
Diseases in Soils May Cause Crop Failures. 3. Too Much
Water in Soils is Harmful. 4. Alkali Salts in Soils is
Injurious. 5. The Toxin Theory of Infertility. 6. Other
Harmful Agents.

CONTENTS XV

CROP PRODUCTION AFFECTED BY SYSTEMS OF CROPPING

XV. CROP ROTATION AND ITS RELATION TO SOIL FERTILITY 203

1. Crop Rotation Defined. Kinds of Rotation. One-Crop
System. 2. Why Crops Should be Grown in Rotation:
(a) Primary object to increase production and help main-
tain it. (6) Specific benefits of rotation: (1) Helps to con-
trol insect pests. (2) Helps to control certain plant diseases.
(3) Favors accumulating of soil organic matter. (4) Tilth
and workability of soils may be improved. (5) Rotation
helps to conserve fertilizing elements. (6) Aids in fertiliza-
tion and liming. (7) Weeds may be better controlled, (c)
Rotation helps to maintain and increase soil fertility.
3. Roration Can Not Take the Place Of Fertilizers. 4. Fac-
tors Determining a Good Rotation, (a) Proper combina-
tion of crops. (6) Proper order in growing the crops. 5.
Crop Rotation Important in Soil Improvement. 6. Some
Practical Rotations. 7. Rotations for Truck Farming and
Vegetable Growing.

APPLICATION OF PRINCIPLES TO MANAGEMENT OF
SPECIAL SOILS

XVI. SOIL EROSION 283

1. Soil Erosion a Serious Problem. 2. Injuries Resulting
from Erosion. 3. Causes of Erosion. 4. Kinds of Erosion.
5. Prevention of Erosion. 6. Stopping Washing and Re-
claiming Eroded Lands.

XVII. THE MANAGEMENT OF MARSH LANDS 293

1. Kinds of Marsh and Swamp Soils. 2. Advantages in
Farming Marsh Lands. 3. Problems in Peat and Muck
Management, and Solutions. 4. Crops for Marsh Lands.
Rotations. 5. Types of Farming for Marsh Lands.

XVIII. SANDS AND THEIR MANAGEMENT 309

1. Important Classes of Sandy Soils. 2. Advantages in
Farming Sands. 3. Problems in Sand Management and
How to Solve Them. 4. Crops for Sands. Crop Rotation.
5. Types of Farming.

XIX. THE MANAGEMENT OF CLAYS AND DEPLETED SILT LOAMS S21

1. Clay Management: (a) Character of clay soils and
their advantages, (ft) Important problems and their solu-
tions, (c) Crops for heavy clays, (d) Rotations and types
of farming. 2. Improvement of depleted silt loams: (a)
Liming a common first consideration. (6) Importance of
fertilizers and organic matter, (c) Proper rotation.

PRINCIPLES OF SOIL FERTILITY APPLIED TO THE FARM
AS A WHOLE

XX. FARM MANAGEMENT AND CROP ROTATION 327

1. Soil Problems are Important Farm-Management Prob-
lems. 2. Diversified Farming and Its Advantages: (a) It
economizes in the use* of labor. (6) A more dependable
income is assured, (c) It permits of crop rotation. 3 Crop

xvi CONTENTS

Rotation an Essential Factor in Successful Farm Manage-
ment: (a) Aids in maintaining and increasing fertility.
(6) Systematizes farm operations, (c) Aids in solving soil
and crop problems. 4. Crop Rotation in Practical Farming.
5. Factors Which Determine Kinds of Rotations. 6. How
to Plan Rotations: (a) When a farm is already stocked.
(6) For a stock farm not yet stocked, (c) For a grain farm
having soil problems, (d) For a truck farm having soil
problems. 7. Rotations — Application and Illustrations.
8. Other Points on Crop Rotation.

XXI. SYSTEMS OF FARMING AND THEIR RELATION TO SOIL FERTILITY 343
1. Systems of Farming — Grain, Stock, Truck and Combina-
tion. 2. Grain Farming vs. Stock Farming: (a) Grain
farming is important. (6) Grain farming has led to soil
depletion, but revised, (c) Stock farming is popular, (d)
Maintaining fertility by stock farming not probable, (e)
Possible to maintain fertility by either grain or stock farm-
ing. (/) Combination of grain and stock farming popular.

f\ A_ A j_ TTT"il i 1 TVI , f t T-11 , • ~r^

of the plant-food elements in farming, (c) Rules for deter-
mining losses and gains, (d) The nitrogen-phosphorus
balance sheet.

OTHER POINTS ON. SOIL MANAGEMENT

XXII. How THE NEEDS OF SOILS MAY BE DETERMINED 355

1. Chemical Analysis has Limitations. 2. Other Factors
to be Considered First Before Chemical Analysis is Made
of Soil. 3. Chemical Analyses and Their Value: Need of
Lime, Tests for Nitrogen, Phosphorus and Potassium.
4. Pot Tests— Not Fully Reliable. 5. Field or Plot Tests
Are Most Reliable: (a) Scientific tests by Experiment
Stations. (6) Practical tests by farmers. 6. Value of
Farm Examinations.

XXIII. PROFITABLE CROP PRODUCTION 369

1. Large Crops not Necessarily the Most Profitable. 2.
Profitable Crop Production Determines Successful Farming.

3. Profits Determine Fertilizer Practice. 4. Important to
Determine the Point at Which Crop Production is Most
Profitable. Value of Untreated Plot. 5. Proper Basis for
Determining Most Profitable Fertilizer. 6. Proper Kind and
Amount of Fertilizers Important : (a) Application of the law
of the minimum, (b) Application of the law of diminishing
returns. 7. Factors Favoring Greatest Profits Per Acre:
(a) When soil is properly fertilized. (6) When high crop
prices prevail.

XXIV. FARMING IN REGIONS OF LIMITED RAINFALL 377

1. Dry-farming of Much Importance. 2. Water Problem
and Soils. 3. Farming Methods — Summary of Results.

4. Crops for Dry-land Farming. 5. Dry-farming Practices.
6. Stock in Dry-land Farming. 7. Good Farming is Essen-
tial to Successful Farming Everywhere.

APPENDIX . . 383

PRODUCTIVE SOILS

INTRODUCTION

THE chief concern of the human race is its physical needs. Its
greatest needs — food and clothing, depend entirely upon the soil
which is intimately associated with life. Myriads of plants and
animals have lived upon the earth for ages and ages because
soil exists.

Every nation is deeply interested in the soil and its crops.
Shall we grow more wheat to meet the demands of our increasing
population, or shall we import it? Shall we meet the demand for
more cotton, or shall it be grown elsewhere? Are our working
people to have meat on their tables in the years to come, or will
the price of meat be beyond their means? These questions can be
answered only by the soil.

Relative Decrease in Wheat and Corn. — During the 30-year
period between 1879 and 1909, the increase in corn production was
45.5 per cent, and in wheat production 48.7 per cent; while the
increase in population for the same period was 83.4 per cent. The
production of corn and wheat did not keep pace with the increase
in population. During this period the exportation of wheat declined.

Actual Decrease in Corn and Wheat. — The Thirteenth United
States Census (1910) showed an absolute decrease in corn and
meat production since the Twelfth Census (1900), while the popu-
lation increased over 20,000,000 — and this in a comparatively new
country ! The extra effort put forth by the farmers and agricultural
organizations to increase production during the World War resulted
in marked increases in the production of corn, grain, meat and dairy
products (Report of the Secretary of Agriculture, 1918).

The United States produces 71.5 per cent of the world's corn
crop and consumes 70 per cent; it produces 18 per cent of the world's
wheat crop and consumes 15 per cent; it produces 27 per cent of
the world's oat crop and consumes 26 per cent; and it produces
6.5 per cent of the world's potato crop and consumes 7 per cent.
Thus there is the possibility of only a small exportation of these
food crops. If the productive power of this country is not
increased, exportation of any food crop must necessarily cease,

1

2 INTRODUCTION

and tne proplcni. of feeding o\ir people will become the more serious.
Shall it be importation of food or shall it be home production? It
is to be noted that there is already a small importation of potatoes.
Relatively Low Yields. — The United States is far from being
the leading nation in yields per acre, as is shown by the following

10-year averages :

Average Yield Per Acre (Bushels)

Crops

England

Germany

United States

Wheat

32.6

28.4

13.9

Oats

44.7

49.3

29.8

Rye

26.7

24.6

15.8

Potatoes

230.0

224.0

96.0

These facts place a responsibility upon every American farmer.
The crop production problem is a national one. The farming of
virgin soils is now practically a thing of the past, and soil depletion
cannot long continue.

What is the reason for the higher crop yields in European farm-
ing? Theirs is an agriculture older than ours. Let us consider the
answers of the agricultural leaders of some of the Old Countries in
reply to the question as to why their average yields per acre of
wheat and other cereal crops have almost doubled in the last
80 or 100 years.

From England: "The factors at work in the increase have been . . .
better cultivation and tillage. . . . The great factor has been the introduction
of fertilizers and purchased feeding stuffs."

From Germany: "In general I assume that of the 100 per cent increase
in the yield can be attributed: To artificial fertilizers, 50 per cent; . . . better
tillage of the soil, 25 per cent; to the use of better seed, 15 per cent; to the better
crop rotation, 10 per cent."

From France: "... we submit in the following figures ... the rela-
tive importance of the different factors (increase in production taken as 100) :
(Extensive Agriculture) . Effect of fertilizers, 70 per cent ; effect of preparation
of the land, 15 to 20 per cent; effect of selection of seed and improved varieties,
5 to 10 per cent."1

It is to be observed that 85 to 90 per cent of the 100 per cent
increase in their crop yields has been the result of better soil man-
agement. Here is a lesson from Europe for us.

Our National Problem. — Shall we wait yet awhile before con-
sidering seriously the better management of our soils? Have we

1 European Practice and American Theory Concerning Soil Fertility.
Illinois Circular No. 142, 1910.

INTRODUCTION 3

not already enough acres of abandoned agricultural lands in this
country? The United States does not stand first in yields per acre,
but it does excel all other nations in rapidity of soil exhaustion.

Nationally and individually, the time to adopt methods to
maintain productiveness and to improve our soils is while we are
prosperous. This task challenges every tiller of the soil, every
farm boy and girl, the dwellers in cities, every agricultural organ-
ization, and all other forces which strive for betterment through
human endeavor. No greater force can man set into action than
the power of the intellect — and this is accomplished through edu-
cation. Then let it be education.

The general sentiment among thinking farmers is — "How
little we know about soils and how much there is to know ! " These
farmers have not had the opportunities for agricultural training
existing today. They cannot now go to school, hence instruction
should be carried to them. This information, as well as that given
to students in all practical or first courses, should not be technical
and lop-sided, but simple, practical and well-balanced so as to
enable our present-day farmers and those of the future to gain a
happy living, and at the same time to conserve the great funda-
mental asset of our Country — the soil.

TO THE TEACHER

It may not be necessary, or time may not permit, to perform
all the exercises indicated. Only those should be selected which
will best supplement the class work. Frequently it becomes
necessary to combine class work, demonstrations and laboratory
exercises, or to make the laboratory exercises demonstrational.
Local conditions should determine in a large degree the exercises
to be selected. Those listed here may suggest others more suitable
to local conditions.

Field trips should be carefully planned to include as many
observations as possible. The leader, or teacher, should first go
over the ground alone in order to map out the trip and determine
what observations are to be made.

The materials needed for demonstrations and laboratory work
are based on one demonstration or exercise.

The demonstrations which require time before the results may
be shown should be started in time to be ready when needed.
(Note demonstrations for Chapters V, VI, VII, VIII, IX, XI, XII.)

4 INTRODUCTION

Students should keep laboratory note books when laboratory
work is given. A definite order should be followed in writing up
each exercise as follows :

Exercise No. — (Number exercises in order performed.)
Object of exercise.

Procedure (state briefly how exercise was conducted).
Results (make use of sketches and tabulated data).
Conclusions (facts brought out or principles illustrated).
Questions (write out questions with answers).

CHAPTER I
THE SOIL AND ITS ORIGIN

What Soil Is. — In its broad meaning, soil is that friable, upper
stratum of the earth composed for the most part of mineral matter
resulting from the breaking up and decay of rocks. It extends to
solid rock — varying in depth from an inch or so to many hundreds

Fia. 1. — A spiral nebula. It is believed that the earth was at one time a revolving mass of

gaseous material.

of feet. Mixed with this mineral matter,1 especially at the surface,
is more or less organic matter incorporated through the subsequent
growth of vegetation.

Soil Is Forming All the Time.— The fact that soil is derived
from rocks implies that it is one of the later products of creation.
All soil, however, was not formed in some particular period in the
early history of the earth — some of it was formed millions of years
ago and some is being formed today.

1 Generally speaking, mineral matter is any substance not formed by plants
or animals. Organic matter is any substance formed by plants or animals.

5

6

THE SOIL AND ITS ORIGIN

Rock Weathering the Soil-forming Process. — The formation
of soil is the result of the slow process of rock weathering, meaning
the breaking up and decay of rocks brought about by the destruc-
tive action of the forces of nature. These forces include :

(a) HEAT and COLD — causing cracking and splitting of rocks
through sudden temperature changes.

(6) FROST — causing splitting and cracking by freezing water.

FIG. 2. — Sugar Bowl Rock, Dells of the Wisconsin River.

disintegrate rocks.

Water wears away and helps to

(c) WIND — causing abrasion through the action of dust and sand
particles carried by it.

(d) ICE — causing grinding as in glacial action.

(e) WATER — a wearing and dissolving agent, also producing
chemical changes2 (Figs. 2 and 3.)

f Oxygen,3 producing chemical change?,

(/) GASES — { Carbon dioxide, or carbonic acid gas, producing
[ chemical changes.

2 Chemical changes are the decay processes in rock weathering.

3 Oxygen is a gas composing 20.7 per cent of the air. Carbon dioxide is a
heavy gas consisting of the elements carbon and oxygen (CO2).

SOIL FORMATION NOT A SIMPLE PKOCMSS 7

Other Forces of Nature. — These weathering agencies are as-
sisted in rock destruction by other forces of nature, such as volcanic
eruptions, earthquakes, the force of gravity, etc., and to a greatey
or less degree by plants and animals. Plants in their growth fre-
quently crack and split rocks because of root expansion, and hasten
rock decay through chemical action caused by certain substances
excreted from their roots. Man "as a destructive creature has cut
down forests and destroyed the natural soil covering of grass and
shrubs. The washing away of the soil which follows very often ex-

FIG. 3. — The " Dutch Wedding," Monumental Park, Colorado. Sandstone rocks
sculptured by the erosive action of water (in past ages) and wind. New International
Cyclopedia.

poses new rock surfaces to the weathering agencies (Fig. 4). Bur-
rowing animals also expose fresh rock surfaces, or openings made by
them facilitate the entrance of weathering agents to lower levels.
Fungi, and even the tiny bacteria lend their aid. Even after plants
arid animals are dead they contribute further to rock decay, since
in their decay acids are formed which hasten the changing of rock
and rock particles into soil.

Soil Formation not a Simple Process. — It is evident that soil
formation is not a simple process, but rather complex and slow. It
began no doubt as soon as the once gaseous and molten earth passed

THE SOIL AND ITS ORIGIN

FIG. 4. — From rock into soil. The lower stratum of the soil has a composition approach-
ing that of crumbled and decayed rock. Lower down the rock characteristics appear more
plainly, and still farther down occurs the solid rock itself.

SOIL OF MANY KINDS 9

into a firm, stony sphere, and made more complicated because of
the eternal forces which wrought such tremendous changes since
the earth began — which forces brought into existence continents
and oceans, lakes and rivers, mountains, hills and valleys, deserts
and prairies.

Weathering Continues Indefinitely. — Weatheringdoes not cease
when it has reduced rocks to soil, but continues to act indefinitely
upon the soil itself. If it were not so the best prairie soils would be
incapable of supporting a single blade of grass. In this sense crops,
vegetation and life are possible upon this earth largely because
of decay.

Soil from Rock May be Observed. — Soil wherever found is
underlaid by some kind of rock — it may be the rock from which the
soil was formed or some foreign rock. Where soil is found Under-
laid by its parent rock there is no definite dividing line between the
solid rock and the soil above it — the one grades into the other. The
lower stratum of the soil has a composition approaching that of
crumbled and decayed rock. Lower down the rock characteristics
appear more plainly, and still farther down occurs the solid
rock itself.

Soils are Carried Away after They Form. — All the soil we see
was not formed from the rock that may be found under it. This is
due to the fact that many soils are carried away after they are
formed and deposited on other rocks. Water, ice and wind are and
have always been the main soil transporting agents.

Soil of Many Kinds. — Because of the source of soil building
materials, the nature of soil formation, the forces to which the earth
has been and is being subjected, and because of the transporting
and mixing action of water, wind and ice, all soil can not be the
same, but must necessarily varyin composition, both physically and
chemically. These variations give rise to. many kinds and types
of soil, and necessitate convenient classification. A knowledge of
these soil variations, classes and types becomes of primary
importance.

Illustration Material for Lessons. — Students should bring to class:

1. Specimens of rocks undergoing weathering.

2. Samples showing gradations of rock into soil.

Field Studies. — 1. Observe if possible the weathering of native rock into
soil, and note the action of the various weathering agents.

2. Observe the transportation and movement of soil.

3. Observe various kinds of soil — note location, etc.

10 THE SOIL AND ITS ORIGIN

QUESTIONS

1. What is soil and when was it formed?

2. Name two classes of materials composing soil.

3. Distinguish between them.

4. What is meant by rock weathering?

5. Name some of the forces which break up arid cause rocks to decay.

6. In what ways do plants and animals aid in the weathering of rocks?

7. Is soil formation a simple process? Explain.

8. When does weathering cease?

9. What is the importance of "soil weathering"?

10. Is it possible to observe the stages in the changing of rock into soil?

11. What are the facts to be observed?

12. In every case is soil formed from the rock found underlying it? Explain.

13. Why should there be many different kinds and types of soil?

14. What kinds have you seen?

15. For an outline summary of this chapter see table of contents.

CHAPTER II

SOIL COMPOSITION, CLASSES AND TYPES

Common Meanings of the Term " Soil." — In the previous
chapter the term "soil" included the total residue resulting from
rock weathering — being hundreds of feet deep in some places. In
common usage the term soil has restricted meanings; viz., it may
mean that portion of the ground which is tilled, or that portion
which is black or dark in color.

Subsoil Defined. — That portion of the ground below the tilled
or dark colored portion is called "subsoil." (Prefix "sub" means
"under.") By some it is considered as that portion below 6%
inches deep and 20 inches deep.

Soil to Mean Tilled Portion. — Soil as it is used in the following
chapters is taken to mean that portion of the ground which is tilled.
This is the more common meaning since it is that portion which is
most important in supplying the needs of crops, and which is most,
affected by farming operations.

Subsoil May Differ Widely from Soil.— With this definition of
soil in mind, it is easy to see that subsoil may have extreme varia-
tions— it may have the same color and composition as the soil or it
may show very little or no similarity either in color or composition.

THE COMPOSITION OF SOIL

The physical or mechanical make-up of dry soil may be briefly
expressed in outline form as follows:

( 1. Mineral particles of various sizes (derived f (a) Sand

Soil components from rocks) $ ®J*

(\c) v^my
{ 2. Organic matter — mostly plant remains.

Sand particles are the coarser and heavier soil grains which do
not cohere when wet (Fig. 5). Between the fingers they feel rough
and gritty. They are the first to settle out of running water carry-
ing sediment — material washed from the upland.

Clay particles are the finest of individual soil grains. When
moistened they become sticky. They settle out of quiet water very
slowly — the finest clay particles are so small that they are known
to remain in suspension for months, or to be scarcely discernible
under a powerful microscope.

11

12 SOIL COMPOSITION, CLASSES AND TYPES

Silt particles are soil grains medium in size between sand and clay.
When moistened, silt has a velvety "feel, " but not sticky like clay.

Sand, silt and clay as used here refer simply to size of individual
soil grains and nothing more.

Organic matter in most soils occurs largely as a well-decomposed
residue, black or dark in color and coating the soil grains. Fre-
quently plant fiber of recent growth can be distinguished.

Humus may be defined as a black, waxy, complex substance

Very Fine clay

FIG. 5. — Diagram illustrating the sizes of soil grains. The coarsest particles grade

into the finest.

of coating the soil grains, and which is derived from partial decay
organic matter. All humus is organic matter, but all organic
matter is not humus.

The term humus is sometimes used as a general term meaning
organic matter. In these chapters we shall use the term "organic
matter" since that is more readily understood.

Soil is a Complex Medium. — What we call soil is something
more than a mere mixture of sand, silt, clay and organic matter.
It is a composite, the framework of which is mineral matter.
Aside from organic matter it contains :

(a) Water (moisture) which in reality is a dilute solution con-
taining weak acids and small amounts of any soluble substance
found in the soil.

(b) Soil organisms — bacteria, fungi and worms. These have

MEANINGS OF TEXTURE AND STRUCTURE COMPARED 13

come to live in the soil by the millions because of the presence of
organic matter which, because of the energy or food stored up in it,
is the source of most of their sustenance and their energy. Some of
these organisms are a detriment to soils, while others, because of
fundamental changes they bring about, are of the greatest im-
portance in crop production.

(c) Air — Soil as a medium for plant growth must contain air.

(d) Salts in greater or less amounts — in dry climates much.

SOIL CLASSIFICATION

Since the building materials of soils are largely mineral
particles which remain more or less the same in size and amounts
in any particular soil, we are afforded a basis whereby soils may
be classified.

Crummy structure Compact structure Sandy structure

FIG. 6. — Diagrams illustrating soil structures.

Soil Texture a Basis for Classification. — The most convenient
and general scheme for soil classification is based on the amounts
of sand, silt and clay soils contain — or in other words, on the basis
of " texture. "

What Soil Texture Means. — Soil texture may be defined as a
quality denoting comparative coarseness or fineness of soils as is
determined by the relative abundance of sand, silt and clay con-
tained in them. For example, a soil having course sand predomi-
nating is a course textured soil, whereas one having much clay is re-
garded as fine textured.

Meanings of Texture and Structure Compared. — Texture
should not be confused with soil "structure" which means the
arrangement of the soil grains (Fig. 6), or which describes the rela-
tion of the soil particles to each other. It is important to remember
that the soil components do not form a mere casual mixture in
which every particle remains separate from every other particle.
With the exception of sands, the soil components, because of the

14 SOIL COMPOSITION, CLASSES AND TYPES

cementing nature of much of the organic matter, group themselves
into compound particles and granules, thus developing a
" crummy" or " granular" structure. When a " heavy" soil does
not crumble, but is a hard, compact mass instead, it may be said to
have a " compact " structure. A sand may be described as having a
"loose" or "sandy" structure.

Soils Classified According to Texture. — Eight principal soil
classes based on texture are recognized. They are here given in an
order ranging from the coarsest to the finest textured soils.
Soil classes How distinguished

1. Medium sand Composed of 80 to 100 per cent sand (much medium

and coarse sand).

2. Fine sand Composed mostly of fine sand.

3. Medium sandy loam . Having 50 to 80 per cent sand.

4. Fine sandy loam Having 50 to 80 per cent fine sand.

5. Loam Composed of 30 to 50 per cent sand and 50 to 70 per

cent silt and clay.

6. Silt loam Containing 50 per cent or more of silt.

7. Clay loam Containing 20 to 50 per cent sand, 20 to 50 per cent

silt, and 20 to 30 per cent clay.

8. Clay Having 30 per cent or more clay.

A soil class is understood to mean all soil of the same texture.
For example, soils consisting of about 50 per cent sand and about
50 per cent silt and clay belong to one and the same class regardless
of where they may be found. By virtue of its texture this class of
soil is named "loam."

A loam is to be defined as a class of soil composed of about half
sand and the remaining half silt and clay (more silt than clay).

Again, a silt loam is to be defined as a class of soil, or a soil class,
containing 50 per cent or more of silt.

Of these classes of soils, silt loams are most widely distributed,
loams take second place, and fine sandy loams third.

In this classification no consideration is given organic matter.
Soils containing much stone or gravel may be described as stony silt
loam or gravelly loam, as the case may be. Gradations may also
occur; such as, silty clay loam, loamy fine sand, etc.

"Marsh" and "swamp" soils are to be regarded as class names
though they are not included in the classification based on texture.

Marsh is commonly interpreted to mean a wet level area
covered with grasses. There are salt and fresh-water marshes.

Swamp is usually understood to mean low, wet areas of fresh
water formation covered with tree growth. Tamarack swamp,
cedar swamp, and cypress swamp are familiar expressions.

SOIL CLASSIFICATION

15

Mechanical Analysis and Mechanical Composition. — In order
to be sure to which class a soil belongs, the amounts of sand, silt
and clay it contains must be determined by laboratory methods
designated as ''mechanical analyses." Such analyses give the
"mechanical composition" of a soil; as, for example:

Dry soil

Mechanical Composition
Per cent of

Soil class

Reason

Sand

Silt

Clay*

A — found to contain
B — found to contain
C — found to contain

15.7
16.9
63.0

68.1
37.9
21.0

15.8
44.4
12.0

Silt loam
Clay
Sandy loam

Contains more than
50 per cent silt.
Contains more than
30 per cent clay
Contains more than
50 per cent sand.

* Per cents total 99.6 — remaining 0.4 per cent consisted of stone and gravel.

" Light " and " Heavy " Soils. — A sandy soil, because of its
high sand content, is comparatively easy to work — for this reason
it is usually regarded as a " light " soil. A soil like clay, on the other
hand, is termed " heavy" because it is much more difficult to till.
By weight sand is the heaviest soil — clay is much lighter.

Soil Classification Based on Mode of Formation. — It is con-
venient to study soils in relation to the manner in which they were
formed or built up. This gives rise to quite a different classifica-
tion, as follows :

1. Residual soils — remaining on rocks where formed.

2. Cumulose soils — deposits of partially decayed vegetation.

3. Alluvial soils — built up by alluvium deposited by flow-
ing water.

4. Glacial soils — formed through glacial action.

5. Marine scils — formed by sediment carried into the sea.

6. Lacustrine soils — formed by sediment carried into lakes.

7. Loess (Zo'<?s), — formed through the accumulation of dust
carried by wind.

8. Colluvial soils — moved down steep slopes by gravity.

The first two groups are ''sedentary" soils, since they have
stayed where they were originally formed. The next five groups
are "transported" soils — the material having been carried and
laid down by water, glaciers and wind. The last named soils are so
called because they moved down steep slopes, due to gravity.

16 SOIL COMPOSITION, CLASSES AND TYPES

Residual soils are underlaid by the rocks from which they were
formed — such as granite, limestone, sandstone, shale and others.
Wherever such soils are found the graduation of rock into soil may
easily be observed. These soils are widely distributed in the
United States — including the Great Western Plains and the larger
portion of the Southern States, excluding the river valleys and the
Atlantic and Gulf Coastal Plains.

If all the soils could have remained where they were formed then
all the soils in the world derived from rocks would be residual. But
this has been impossible because of the forces which have been and
are still at work effecting changes on the earth.

Cumulose soils are deposits of vegetable matter accumulated
most commonly in what used to be shallow bays, lakes and ponds,
and preserved because they were covered or saturated with water.
It is common to see water plants such as flags, mosses, reeds and

FIG. 7. — Diagram showing peat formation and a floating bog; cc, vegetable growth
on surface of pond; dd, partially decayed organic matter accumulating on bottom; ee,
climbing bog. (Shaler.)

sedges, growing, for example, along the shores of a pond. These
plants die, sink to the bottom and are wholly or partially preserved
by stagnant water which prevents or inhibits their decay. Some-
times "floating bogs" are formed which become thicker and thicker,
and as they thicken gradually sink to the bottom (Fig. 7) . In either
case there comes a time when the shallow body of water becomes
filled with a soft, spongy mass — the final stage in the formation
of " peat."

Peat when dry is the lightest of soils, and may be black, brown
or reddish in color. It is commonly described as "raw" when the
plant remains can be easily recognized, and "well decomposed"
when the plant remains have lost their identity. Peat is a material
much used for fuel in countries of the Old World.

Muck. — When considerable sediment is mixed with peat the
resulting soil is called "muck. " It is more decomposed, firmer and
heavier in weight than peat.

Occurrence and Value of Peat and Muck Soils. — Peat and
muck soils occupy local areas ranging from a few to thousands of
acres in extent, and they may vary in depth from a few inches to

THE SOURCES OF THE SEDIMENT

17

several feet. Some are formed in fresh and others in salt water
(Fig. 8). They are not confined entirely to lowlands, but may occur
on hill tops and even on hill sides in depressions kept wet the year
round. On many of them, in their natural state, wild grasses
grow — on others trees and shrubs. When artificially well drained
most of them can be converted into valuable agricultural lands.

Alluvial soils are found along streams, and are built of the
alluvium carried and deposited by them during flood flow. When
muddy streams overflow their banks, the flow over the flooded land
is retarded, consequently the sand settles out, then the silt, and

FIG. 8. — A bed of peat four feet deep underlaid by a 3-foot bed of marl, which in turn is
underlaid by sand and then clay.

finally the clay — if the flow is nearly or completely checked.
Through this deposition, therefore, low level areas are gradually
brought to higher levels. Many streams during the past ages have
greatly subsided, leaving high and dry many level and productive
expanses of these water-formed soils.

The sources of the sediment carried by streams are mainly the
uplands drained by them. Heavy rains and melting snows are
responsible for the land erosion so commonly seen in hilly or "roll-
ing" sections. The sand, silt and clay particles carried into streams
may be gathered from many kinds of soils and which in turn form
new kinds. Geologists have estimated that the United States
is being planed down at an average rate of one inch in 760 years,
2

18 SOIL COMPOSITION, CLASSES AND TYPES

but denuded slopes may lose several feet in a year. Not all
the alluvium carried by rivers is deposited on either side of
their courses before the sea is reached. Indeed, it has been
estimated that the Mississippi river carries into the Gulf of
Mexico each year an amount of sediment equivalent to a pile
of sand and mud one mile square and 268 feet thick. What
becomes of all this material?

When in a well drained condition, alluvial soils are usually
rich and productive. Many soils are kept productive because
of rich sediments deposited on them. The soils in the Nile
Valley in Egypt are splendid illustrations of this natural method
of fertilization.

Glacial soils or " glacial drift" soils are so called because the
material composing them was transported, mixed and built up
through the action of glaciers or huge ice sheets many thousands of
years ago. Though this seems a long time, nevertheless these are
regarded as young in comparison with residual soils.

The Story of the Glaciers. — Among the many wonderful
chapters in the history of the earth recorded in rocks, mountains,
hills and valleys, that of the Great Ice Age is comparatively easy to
interpret. Abundant evidence points to the fact that at some re-
mote time the greater portion of the northern part of North Amer-
ica was covered by great sheets of ice resulting from the accumu-
lation of snows due to climatic changes. These great ice sheets
moved southward and invaded the northern part of what is now
the United States. In the central portion the ice extended as far
south as the Missouri River and southern Illinois, Indiana and
Ohio (Fig. 9).

The Ice Age, especially so far as the north central portion of
the United States is concerned, does not mean the invasion and
melting of just one immense ice sheet or glacier, but it includes at
least five great and separate ice periods. During some of these
periods, notably the first ones, the ice sheets extended farther
west and south than during other periods. The effect of the Kansan
Drift, one of the first invading ice sheets, is best observed in Kansas,
hence the name. This is supposed to have occurred not less than
400,000 years ago. The last invasion, made during the Wisconsin
Glacial Period, is estimated to have occurred 20 to 50 thousand
years ago. There is strong evidence to indicate that between
each of the five ice periods or stages the climate was tropical
or semi-tropical.

EFFECT OF THE GLACIERS

19

Effect of the Glaciers. — These invading and melting ice sheets
produced profound effects upon the country over which they
moved. In thickness they varied from a few feet at their margins

FIG. 9. — Map showing the extent of the ice sheet over North America. Note, the
driftless area, covering a portion of what is now Wisconsin, Iowa and Illinois. (Chamber-
lain and Salisbury.)

to several thousand feet at their centers. They were thick enough
to slide over the high mountains of the New England States.
In their movement rocks were ground to powder, the pre-exist-
ing soil mantle was swept away, some old valleys were filled
up and new ones were gouged out, rivers were turned from their

20

SOIL COMPOSITION, CLASSES AND TYPES

courses, and, when the ice melted a new soil called ''glacial drift"
was laid down. Most of this "drift" material was not carried

FIG. 10. — Whence came this large bowlder?''' The glaciers brought it many miles from the
north. The machine in the background is a stone puller. (Wisconsin.)

FIG. 11. — Kames — round and oval hills formed through glacial action. Wisconsin Geol.
Survey. (Fenneman.)

any great distance by the glaciers, though the streams which ran
from the melting ice carried much sediment miles beyond the
area covered by the ice sheets, and deposited it, as alluvium,
in their valleys.

MARINE AND LACUSTRINE SOILS 21

Low ranges and hills consisting of " glacial till" or " bowlder
clay" were brought into existence. At this time, too, numerous
lakes were formed, many of which have long since filled up or
disappeared. "Rolling" topography and scattering bowlders of
all sizes and kinds are other characteristics of a glaciated country
(Figs. 10 and 11).

Quality of Glacial Soils. — In general, glacial soils have wide
variations; many are comparatively " heavy," hence silt and clay
loams are common. Some are very stony (Fig. 12), and many
are in need of drainage. Great variations exist as to their
agricultural value.

FIG. 12. — The inside of some of the glacial deposits. This deposit consists of very stony
and gravelly glacial till. Wisconsin. (King.)

Marine and lacustrine soils are soils derived from material
accumulated on the sea bottom and in glacial lakes, respectively.
The coarser and heavier particles settled to the bottom near shore,
and the finer silt and clay were carried out into deep water. These
deposits vary in thickness, and in case of marine deposits particu-
larly, commonly consist of layers of coarse and fine material.
Because of changes in the earth during the past ages — such as the
disappearance of old lakes and rise in land elevations, much of this
material deposited in the sea and lakes during ages past has
become exposed and is now called marine or lacustrine soil as the
case may be. Nearly all the soils of the Atlantic and Gulf Coastal
Plains are of marine origin. They are especially adapted to the
growing of cotton, corn, peanuts, melons and fruit.

22 SOIL COMPOSITION, CLASSES AND TYPES

The fertile soils in the valley of the Red River of the North
and of many large areas bordering on the Great Lakes are of
lake origin.

Loess (lo'e's) is soil formed through the accumulation of dust
blown and dropped in favoring localities by wind during long
periods of time. These deposits, no doubt, were centuries in forma-
tion, beginning after the disappearance of the glaciers. During
the Ice Age much fine material was carried many miles south of
the ice sheets by running water coming from the melting glaciers.
Immense quantities were deposited in what is now the Missouri
Valley. After the glaciers melted away it is believed a long dry
period followed during which time strong westerly winds picked
up this fine material and dropped it over thousands of square miles
in the central part of the Mississippi Valley. Loess is also found
in Washington, Oregon and other parts of the United States.
These deposits vary in thickness from a few inches to many feet.
In China loess is found covering immense areas, in some places
extending in depth to several thousand feet.

Loess soils are free from stones, and are considered the richest
soils in the world. The fact that the famous Corn Belt of
the Mississippi Valley includes much loess is indicative of
its productiveness.

Colluvial soils are found at the bottom of steep slopes — they
accumulate there because of the force of gravity. Sometimes
avalanches bring about the quickest downward movement of soil
and rocks from the steep slopes. From the nature of their forma-
tion these soils must necessarily consist of more or less mixed mate-
rial. Often they are made up largely of fragments of rocks brought
down by gravity from the heights above. Generally they are
coarse, loose soils and not well adapted for cultivation.

Soils Easily Described. — Now that we have learned how soils
may be grouped into classes according to their texture, and how
they differ in the manner in which they were formed, we can
easily describe them, and in a general way, distinguish one kind
from another; for example, we may have a residual silt loam on
limestone, or a residual sandy soil on sandstone, or a glacial clay
loam, an alluvial sandy loam, a glacial loam, or a loessial silt loam, etc.

SOIL TYPES

Soil Mapping. — The United States Bureau of Soil in cooper-
ation with the several states and territories has surveyed and

1

FIG. 13. — The United States is divided into thirteen soil provinces'-and regioi

cilitate the correlation of_soil types and series. (Bureau of Soils Bui. 96, 1913.)

DISTINGUISHING OF SOILS SIMPLIFIED 23

mapped hundreds of thousands of acres of soil. Each soil
map is accompanied by a report describing in detail the nat-
ure and agricultural value of the soils surveyed. These
surveys are usually made by counties and are based on the
theory that all soils are not equally suited to the production of
the same crops.

One Loam May Differ Widely from Another. — Though a class
of soil consisting of about half sand and the remaining half silt
and clay, for example, is a loam wherever found, yet a loam in
Wisconsin may differ in ten distinct ways from a loam in Missis-
sippi, and have dissimilar crop adaptation. In order, therefore,
to distinguish clearly between these two particular loams, long
descriptions must necessarily be given each one, concerning man-
ner of formation, kind of material from which formed, natural
drainage, color, amount of organic matter, structure, subsoil and
certain chemical properties.

Distinguishing of Soils Simplified. — In soil mapping it would
be very inconvenient, indeed, if it were not possible to designate the
different soils without describing each in its fullest detail, especially
since there are so many different kinds of soils in the United States
to be correlated.

Soil descriptions concerning origin, etc., may be expressed in
single words; for example, "Dunkirk," " Greenville," etc. These
names used in describing soils are derived from the name of some
town, village, county or natural feature existing in the section or
region where the soil is first identified or is best developed.

Dunkirk, as it is used in describing soils, implies that such
soils are derived from sandstone, shale and limestone material
carried as sediment into pre-existing glacial lakes; they have good
natural drainage; are gray to brown in color, and have a yel-
lowish or light brown subsoil. These soils are desirable for
general farming.

Greenville is a descriptive name signifying that such soils are
of marine origin- — built up by material washed from the Piedmont-
Appalachian region into the ocean which at one time encroached
upon the continent; they are red in color; have a dark red subsoil;
and are friable and well drained. They are well adapted to cotton,
corn, forage crops and oats.

Wherever a loam is found to which will fit the description
implied in " Dunkirk," that soil is specified as "Dunkirk loam."
And wherever a loam is found to which the descriptive term

24 SOIL COMPOSITION, CLASSES AND TYPES

"Greenville" may be applied, that soil is specified as "Green-
ville loam."

Soils specified in this manner are called "types." Thus
"Dunkirk loam" and "Greenville loam" are the names of two
types of soil.

Soil Type Defined. — A soil type may be defined as soil that has
similar characteristics regarding texture, mode of forma-
tion, origin of material, color, natural drainage, organic matter,
and subsoil.

Types may be Grouped into Series. — Soil types may be classi-
fied or arranged into groups called "series." This is possible
because two or more soil types may have the same general charac-
teristics regarding mode of formation, range of color, etc. For
example, we have the following types grouped into a series:1

Dunkirk sand
Dunkirk fine sand
Dunkirk sandy loam
Dunkirk fine sandy loam
Dunkirk loam
Dunkirk silt loam
Dunkirk clay loam
Dunkirk clay

! A soil series. (Dunkirk series.)

In a similar manner are derived Greenville series, Miami
series, Volusia series and many others. The soil types composing
a series differ mainly in texture and productive power.

Soil Series Defined. — A soil series may be defined as a
group of soil types similar hi all respects except in texture
and productiveness.

Soil Classification in Soil Survey. — In soil survey and mapping,
type is the unit used in soil classification. Types having similar
general characteristics aside from texture are classified in series.

To facilitate the correlation of soil types and series the United
States Bureau of Soils has divided the United States generally
into thirteen soil provinces and regions (Fig. 13). The types of
soil derived through glacial and wind actions are to be found largely
within the Glacial and Loessial province. Types of lake origin are
included in the Glacial Lake and River Terrace province. Types
of marine origin are to be found in the Atlantic and Gulf Coastal
Plains province, etc,

JThe word "series" may be used in both a singular and plural sense.

MORE ABOUT SOIL TYPES 25

More About Soil Types. — It is to be observed that a type name
is usually made up of the name of a soil class added to a name
which indicates its general characteristics and which determines
the series to which it belongs as:

Dunkirk sandy loam
(series) (soil class)

Knox silt loam, Cecil loam, Dekalb silt loam, Hagerstown
loam, Genesee loam, Bozeman silt loam, Gila silt loam and Salt
Lake loam are eight types representing as many series. Though
these types are widely scattered throughout the United States, yet
they may be grouped into two classes; viz., loam and silt loam.

It is possible to have two types differing from each other in
several distinct ways, or in just one respect.

Peat and muck are two special types of soils.

Peat may be denned as a soil type consisting of from 50 to
95 per cent organic matter (p. 16).

Muck may be defined as a type of soil which consists of from
15 to 50 per cent of well-decomposed organic matter and 50 to
85 per cent mineral matter. The mineral matter in muck consists
of sand, silt and clay particles deposited by water or wind during
its formation.

Meadow may also be considered a special, or miscellaneous,
type of soil, meaning first bottom land which is low, poorly drained,
and subject to overflow. The texture is so variable that no sepa-
ration into established types can be made.

It is possible on some large farms to map a dozen or more
types which may be grouped into three or more series.

Within a single state more than a hundred types of soils have
been mapped — in Wisconsin, for example, more than 125 types
grouped into more than 30 series.

In the United States there have been mapped thus far more
than 2900 types classified in more than 740 series (Fig. 13).

Illustration Material for Lessons. — 1. Two or three samples of soil —
natural and with organic matter burned out. Note loss of weight, change of
color and any other changes.

2. Samples of various colored soils — include some subsoils. Why do soils
vary in color?

3. Cftacial pebbles and any other material showing glacial action.

4. A soil map to show how soils are mapped.

5. Three or more types of soil belonging to the same series to illustrate
soil classification according to type.

6. A state map to illustrate land description — township, range, section, etc.

26

SOIL COMPOSITION, CLASSES AND TYPES

Demonstrations. — Materials Needed. — Four large, clear-glass bottles; a
small amount of clean sand, silt, some clay, and two or more tablespoonfuls
of loam.

To Show the Comparative Rate of Settling of Sand, Silt and Clay Particles
Out of Water. — Procedure. — Have prepared 4 large, clear-glass bottles and fill
each about three-quarters full of water. Place in one some sand, in another
some silt, in the third some clay, and in the fourth a tablespoonful or more
of loam. Cork. Shake each thoroughly, invert, and note the rate of settling
of the soil particles.

Questions. — (a) Why should the banks of a stream which overflows often
be higher than the land farther back?

(b) A river flows southward. In the middle of the stream is a sand island
which becomes covered at high water. On which end (north or south) of the
island will the fine sand be found? Why?

(c) During a heavy rainstorm a gully was formed on a sloping field of
heavy silt loam soil. Below the mouth of the gully on the field below consider-
able sand was deposited. Where did the sand come from?

Laboratory Exercises. — Materials Needed.— A hand lens; a high power
microscope if available; a dozen tumblers or other dishes; a small baking
powder can; 2 to 4 quarts of each of the eight important soil classes, also muck
and peat; a balance; soil maps; state map showing township and range.

To Examine the Building Material of Soils. — Procedure.— With the aid of
a hand lens examine a pinch of sand and a pinch of loam. Distinguish between
sand, silt and clay particles. (Set up a high power microscope if convenient.)

Questions. — What are sand particles? Silt? Clay particles?

To Study Soil Structures. — (Arrangement of soil particles.) Procedure.—
With the aid of a hand lens examine the structure of a mass of clay. Of sand.
Of crummy silt loam. Illustrate observations with drawings.

Questions. — (a) Of what materials are soil crumbs composed?

(6) What binds the soil particles into crumbs or granules?

To Study Texture of Soils. — Procedure. — Place in tumblers or in other
convenient dishes, dry and typical samples of the eight important classes of
soil (based on texture). Vary the color as much as possible, and have dupli-
cates of some of the classes. Provide a moist sample of each. Include muck
and peat in this exercise. Record results as follows:

Soil classes named in
order according to
texture

How distinguished *

Characteristics
Note "feel," whether
gritty, velvety or sticky

Per cent
sand

Per cent
silt

Per cent
clay

* Teacher should supply percentage ranges of sand, silt and clay.

Questions. — (a) Explain this statement — "A sand is not necessarily
all sand."

(6) Give meaning of "A clay must contain at least 30 per cent clay."

(c) What is a loam?

(d) What is a loamy soil?

(e) What makes a soil loamy?

(f) What is a heavy silt loam?

QUESTIONS

27

To Distinguish Soil Classes. — Procedure. — Proceed as in Exercise No. 3,
only number the samples instead of naming them. Provide a new set of
samples if possible. Include muck and peat in the unknowns. Determine
the soil classes.

To Determine the Difference in the Weight of Soils. — Procedure. — Fill a
small baking powder can full of air-dry sand and weigh. In the same manner
weigh a dry sandy loam, a silt loam, a clay, a muck, and a peat. Use a 20-mesh
screen to separate out all coarse particles. Record results as follows:

Soil

Weight of soil plus can

Weight of can

Weight of soil

Questions. — (a) What is a so-called "heavy" soil?
(6) "Light "soil?

(c) What per cent heavier is the dry clay than the peat?

(d) What per cent heavier is the dry sand than the peat?

To Learn How to Use a Soil Map. — Procedure. — Procure from the State
Experiment Station, College of Agriculture or from the United States Depart-
ment of Agriculture several soil maps of counties in the state. Select one
county map and answer the following questions:

(a)
(b)

Soil map of what county?

Give the boundary of the county in terms of township and range.

Does this description check with that on the state map?

Name the predominating soil classes found in the county.

Name the predominating soil types found in the county.

Give the land description of the section of land in the northwest corner
of the county.

(g) Name the types of soil mapped in this section.

Field Studies. — 1. Observe different soils based on mode of formation.

2. Observe different types of soil and note why different types.

QUESTIONS

1. What are the common meanings given to "soil"? Subsoil?

2. What does a farmer mean when he says, " My soil is three feet deep and is

underlaid by sandy clay?''

3. In our study of soils in relation to crop production what is the meaning

of soil to be understood? What then is subsoil to mean?

4. Name and describe the soil components.

5. Is soil a simple or complex substance? Explain.

6. What is the most convenient way of classifying soils?

7. Distinguish between soil texture and structure. What makes a soil coarse

textured or fine textured? What structures may soils have?

8. Name the eight principal soil classes based on texture in order from the

coarsest to the finest textured. Give meaning of soil class.

9. A certain soil is found to contain 2 per cent coarse sand, 3 per cent medium

sand, 22 per cent fine sand, 35 per cent very fine sand, 27 per cent silt,
and 10 per cent clay. To what class does this soil belong?

10. What two meanings may be given to "sand"? To clay?

11. What is meant by "loam"? Clay loam? Fine sandy loam? Grav-

elly loam?

12. How are "marsh" and "swamp" soils to be regarded?

28 SOIL COMPOSITION, CLASSES AND TYPES

13. What is meant by the mechanical composition of a soil?

14. Distinguish between "light" and "heavy" soils.

15. What are residual soils? Is peat one of them?

16. Name and describe the transported soils.

17. Tell the story of the glaciers. •

18. What is peat? Describe its formation. What is "raw" peat? What

is muck?

19. Can we have soils that may be described as residual alluvial soil; stony

loess; glacial sandy loam; or cumulose silt loam? Explain.

20. What is soil mapping?

21. How may a loam differ from another loam? How may the two be dis-

tinguished from each other?

22. What is a soil type? Illustrate.

23. How may soil types be classified or grouped?

24. What is meant by a soil series?

25. Are peat and muck soils to be regarded as classes or types of soil? Dis-

tinguish clearly between peat and muck. What is meadow?

26. Describe the conditions which lead to the formation of a "marsh" or

"swamp" soil which you have seen.

27. For an outline summary of the chapter see table of contents.

CHAPTER III

CHEMICAL COMPOSITION OF SOILS AND ITS RELATION
TO PLANTS AND ANIMALS

IN the previous chapter it has been shown how the physical
composition of soils, their mode of formation, and their charac-
teristics have given rise to several classes and many types of soils.
In this chapter soils shall be considered from a chemical point of
view, and in this respect their relation to plants and animals noted.

FIG. 14. — A few soil grains enlarged. A sand particle or a clay particle may represent
a combination of the elements silicon and oxygen; or a combination of potassium, alumi-
num, silicon and oxygen, etc.

Soil Materials Composed of Elements. — The building materials
of soils, as has been learned, are mineral particles and organic
matter. These substances, like all material things, are composed
of chemical elements.1 Thus, when a soil is taken into a chemical
laboratory and analyzed, its chemical composition is obtained and
this composition, as of nearly all substances, may be expressed in
two ways; viz., as elements and as oxides of elements; that is, the
elements united with oxygen (Fig. 14).

Chemical Composition of Soils. — In order to make simple and

1 Chemical elements are substances that cannot be reduced to anything
else. For example, iron, carbon, hydrogen and oxygen are elements, since
-they cannot be split up into anything else. Water is not an element because
it can be reduced to something else; viz., two elements — hydrogen and oxygen.

30

CHEMICAL COMPOSITION OF SOILS

plain the chemical composition of soils, the following table has been
constructed which may serve as a key to the knowledge of chemistry
required in further study. Only the more common and important
elements are named. The more common oxides are also named
for the purpose of avoiding any confusion when these names
are used. The chemical symbols2 and formulas will help to
fix in mind the differences between some of the elements
and their oxides.

Chemical Composition of Dry Soils Expressed as Elements and Some of
Their Oxides

Mineral elements

Symbols of
elements

Oxides of elements

Formulas of
oxides

Silicon

Si

Silica

SiO2

Aluminum .

Al

Alumina

A12O3

Iron

Fe*

Iron rust .

Calcium
Magnesium

Ca
Mg

Lime
Magnesia

CaO
MgO

Sodium

Na*

Potassium

K*

"Potash"

K20

Phosphorus

P

" Phosphoric acid"

P206

Sulfur
[Non-mineral]
Carbon

S

c

Sulfur fumes
Carbon dioxide

SO3
CO2

Nitrogen

N

Hydrogen

H

Oxveen . .

O

* It is to be observed that the symbols of ten of these elements are derived from their
common names. The symbols for iron, sodium and potassium are derived from their Latin
names; viz., ferrum (Fe), natrium (Na) and kalium (K).

Elements Exist in Combined Forms. — These elements do not
exist in soils separate from each other, but occur in united forms.
Two or more are combined to form the soil particles which can be
seen. For example, a sand, silt or clay particle may represent a
combination of silicon and oxygen; or potassium, aluminum,
silicon and oxygen; or calcium, magnesium, carbon and oxygen,
etc. A particle of organic matter may represent a complex com-
bination of nitrogen with practically all the elements.

The Elements and Their Characteristics. — Oxygen is the most
common and abundant element on the earth. In the free state it
is a colorless, odorless and tasteless gas slightly heavier than air,

formulas

for

united with two atoms of hydrogen.

MAGNESIUM 31

and slightly soluble in water. It is a very active substance, com-
bining directly with nearly all the known elements at ordinary
temperature. A compound formed through the union of any ele-
ment with oxygen is called an oxide. Water is the oxide of hydro-
gen (H2O). Iron rust is the oxide of iron. At high temperature
oxygen combines vigorously with carbon with accompanying
evolution of heat and light, as in burning.

Oxygen is necessary for all animal life. Good blood owes its
red color to a good supply of oxygen. It is of interest to know that
nearly one-half of an average soil is oxygen by weight. Water is
90 per cent oxygen. By weight, air is 23.2 per cent oxygen.
Rocks of the earth consist of 44 to 48 per cent of this element.

Silicon. — Next to oxygen, silicon is the most abundant element.
More than one-fourth of the crust of the earth is silicon. Quartz
sand is the oxide of silicon. Some mountains are largely sili-
con oxide. In its free state silicon is a brittle solid, having a
metallic luster.

Aluminum is widely distributed in nature, constituting 8 per
cent of the earth's crust. It has a great attraction for oxygen.
It is found in pure clay and in nearly all common rocks. In the
pure form aluminum is a silver-white, lustrous metal about one-
third as heavy as iron. It is used largely in the manufacture of
cooking utensils and for many other useful things, such as paint,
alum, etc.

Iron — Pure iron is a white and fairly soft metal. It rusts
easily in moist air and in salty solutions. Many farmers put grease
on plow mold-boards and cultivator teeth to keep off the oxygen
and thus prevent rusting. Iron is very abundant and widely
distributed. All soils and rocks contain iron in some combined form.

Calcium is always found in combined forms because it is a very
active element. In its pure form calcium is a fairly hard, silver-
white metal. This is a widely distributed element. It is an impor-
tant constituent of bones, egg shells, limestone, coral, marble and
natural chalk.

Magnesium is widely distributed in nature, and occurs in large
quantities. As an element it is a silver-white metal which burns
in the air with a brilliant white light. More than one-half of
flash light is magnesium powder. Many magnesium compounds
are found in soils. Certain common rocks (dolomitic limestone)
.are composed of calcium and magnesium carbonates in nearly
equal proportions.

32 CHEMICAL COMPOSITION OF SOILS

Sodium is never found in the free state, but always combined
with other elements. At ordinary temperature sodium is soft
like wax, and it is so active that it must be kept under petroleum
oil to exclude all oxygen and moisture. Common table salt is
sodium combined with chlorine (sodium chloride). All sodium
came originally from rocks.

Potassium is very similar to sodium in its chemical properties.
This element is never found in its pure form. Like sodium, it is
a soft, silver-white, wax-like metal which reacts vigorously with
water. Pure potassium, therefore, must be kept under petroleum oil.
Potassium is widely distributed in nature. A considerable amount
is present in mineral soils. It is found in the ash of plants in the
form of a compound called potash. Large amounts of potassium
salts are found in Germany and France. Potassium is a common
constituent of potash fertilizers.

Phosphorus does not occur alone in nature because of its great
attraction for oxygen. In its pure form it is a pale yellow, wax-
like solid and very poisonous. Phosphorus is also a very active
substance. Since it catches fire easily in air it has to be kept
under water in air-tight cans. Phosphorus is a common constitu-
ent of bones and of compounds called phosphates. Soils con-
tain a comparatively small amount of this element. Most phos-
phorus of commerce is used in making matches.

Sulfur is a common substance. It is yellow in color and may
occur as crystals or as flour. Many rich deposits of sulfur are
found in Texas, Louisiana and Mexico. It is also found in com-
bination with some of the metals, as lead, iron, zinc, etc. Sulfur
is much used in the making of sulfuric acid, black gun-powder,
hard rubber, etc.

Carbon occurs in the free state as charcoal, graphite, coke,
soot, lampblack, bone black, diamonds, etc. Large quantities of
carbon are found in the form of coal, which represent the remains
of vegetation of past geological ages. Carbon is the most im-
portant constituent of all plants and animals. When carbon
burns it unites with oxygen and forms carbon dioxide gas
(CO2). Carbon in the soil is found mostly in the organic matter
and carbonates.

Nitrogen in its free state is a colorless, odorless, tasteless and
inert gas. Air is 76.8 per cent nitrogen by weight. In the gaseous
form nitrogen does not combine to assist in life processes, yet in
combined form this same element is absolutely essential to all life.

HOW NITROGEN IS HELD IN SOILS 33

The original source of all nitrogen is the atmosphere. Nitrogen is
the important element in ammonia and in all nitrates. In the
soil it is found mainly as compounds in organic matter.

Hydrogen in its pure form is a colorless, odorless and tasteless
gas. It is the lightest of all known substances. It is the most
widely distributed element in the universe, being found in the sun
and the stars. On the earth it is found mostly combined with
other elements. It is an essential constituent of water. When
hydrogen gas burns, the resulting compound is water — hence the
name hydrogen (water generator). Hydrogen is an essential part
of all plants and animals.

The Mineral Elements. — Silicon, aluminum, iron, calcium,
magnesium, sodium, potassium, phosphorus and sulfur are fre-
quently called the mineral elements (see table).

The Elements Crops Take From Soils.— The elements that
crops take from the soil components and which are absolutely
necessary for plant growth are iron, calcium, magnesium, potas-
sium, phosphorus, sulfur and nitrogen. All of these except nitrogen
are the essential mineral elements required by all crops.

The elements most commonly deficient in soils and which
affect crop yields the most are nitrogen (N), phosphorus (P), and
potassium (K). These three are, therefore, commonly regarded as
the fertilizing elements. With these might be included calcium (Ca).
Some regard sulfur fully as important as phosphorus in crop pro-
duction. Conclusive evidence, however, is lacking. Some tests
seem to show that certain soils require sulfur to aid in obtaining
larger crop yields.

Supply of Important Elements not Large. — The total amount
of these four elements in a sand is more often less than 2 per cent;
in a productive silt loam often less than 5 per cent. The soil
supply of nitrogen, phosphorus, potassium and calcium, therefore,
is not large.

Of the essential elements, crops require the least iron, yet
soils are rich in iron. Generally speaking, more than 85 per cent
of soils consists of oxygen, silicon and aluminum. This oxygen
exists in the soil in the form of insoluble compounds and is not used
by plants. Both silicon and aluminum are non-essential to
plant growth.

How Nitrogen is Held in Soils. — Nitrogen in free form is a gas,
.a component of air. The nitrogen which makes up a part of the
composition of soils is held in soils largely as organic matter.
3

34 CHEMICAL COMPOSITION OF SOILS

Before plants can secure this nitrogen for their growth the organic
matter must decay. In a similar manner the mineral soil particles
must decay or partially dissolve before plants can obtain the
essential mineral elements.

Lime, Its True Meaning. — Lime is the oxide of the element
calcium, or calcium oxide (CaO). Pure burnt lime or quick-lime
is nothing else than calcium oxide. Lime does not exist in soils
in the form as indicated by its symbol; it is to be found in more
complex substances. It is to be remembered that the calcium con-
, tent of any substance may be expressed as per cent calcium (Ca)
or as per cent lime (CaO).

Potash, Its Common Meaning. — The word potash is commonly
used to mean the oxide of the element potassium, or potassium
oxide (K2O).3 Its true meaning, however, is potassium carbonate,
a soluble alkali salt obtained by leaching wood ashes. True
potash is not a substance that can be represented by the formula
(K2O) ; it is a more complex substance, as indicated by the for-
mula K2CO3.

The potassium content of soils or of any fertilizing material
may be expressed as per cent potassium (K), and commonly as
per cent "potash" (K2O).

" Phosphoric acid " is the name frequently given to the oxide
of the element phosphorus, (P2O5).4 It does not exist in nature;
nevertheless it can be made in a chemical laboratory.

The phosphorus content of soils or of any fertilizing substance
may be expressed as the element phosphorus (P), and as it is
frequently expressed, as phosphoric acid (PA).

Chemical Composition of Soils Influences Plant Growth. —
This brief discussion concerning the chemical composition of soils
is sufficient to give us the idea that a loam, silt loam or any other
class or type of soil is a complex chemical substance down into
which land plants send their roots, not only to anchor themselves
but to obtain water and elements necessary for growth. It is
reasonable, therefore, to believe that the chemical composition
of soils influences the growth and development of plants in a
greater or less degree (Fig. 15).

Chemical Composition of Plants Similar to That of Soils. — For
centuries no one knew just what plants were made of or how they

3 The formula K^O means two atoms of potassium united with one atom
of oxygen.

4 The formula P2O5 signifies the union of two atoms of phosphorus with
five atoms of oxygen.

SOURCES OF ELEMENTS PLANTS REQUIRE

35

About 290 years ago it was thought that a plant was
>thing more than water that had undergone a mysterious change

the soil. Only

thin compara-
rely recent years
it been found

it the chemical
c o m p o s i t ion of
plants is quite simi-
lar to that of soils.

The elements
required by plants
and without which
they cannot grow
are ten in number;
viz., nitrogen, phos-
phorus, potassium,
calcium, mag-
nesium, sulfur, iron,
carbon, oxygen and
hydrogen. All the
mineral elements
are to be found in
ashes.

Silicon, sodium,
aluminum and
other elements are
found in ash but
they are not neces-
sarily essential to
plant growth, since
plants can grow
without them. Ash,
then, is the mineral
portion of plants.

Sources of Ele-
ments Plants Re-
quire. — Plants
secure the elements they require from the following sources:

1. The soil — furnishing nitrogen and mineral elements.

2. The soil water — furnishing oxygen and hydrogen.

3. The air — furnishing carbon and oxygen.

Fio. 15. — The root system of a potato plant in a per-
meable soil. This also illustrates the sources of the elements
required by plants. (After Rotmistrov.)

36 CHEMICAL COMPOSITION OF SOILS

How Plants Secure Their Nitrogen and Carbon. — Plants do
not and cannot use nitrogen in its gaseous form, hence they do not
take in any nitrogen directly from the air through their leaves.
All nitrogen used by plants is taken in through their roots.5

Practically all the carbon contained in plants is taken directly
from the air through the leaves in the form of carbon dioxide (CO2) .

Much Carbon is Used by Plants. — A bushel of shelled corn
contains about 25 pounds of carbon and one pound of ash. A ton
of clover hay contains 950 pounds of carbon and about 140 pounds

] IT (Carbon dioxide)

PL A N T5 furmsh foods for An / ma Is

(Man and beast)

*

^ sQ I I (Water, nitrogen and mineral elements/

FIG. 16. — The relation of plants to the soil and air on the one hand and to animals

on the other.

of mineral matter (ash). These two facts show the importance
of both carbon and mineral elements in the production of crops.
Chemical Composition of an Animal Body is Similar to That of
Plants and Soil. — Plants are consumed by animals, and this means
that the elements composing the animal body are secured mainly
from plants. Thus it is not surprising that the chemical composi-
tion of an animal body should be similar to that of plants. The
ash of an animal body contains the same kinds of mineral elements
as are found in the ash of plants and in soils. In reality, therefore,
the ash of an animal body is nothing more than the "dust" of the

5 This seems contrary to general opinion especially as regards clover,
alfalfa and other legumes. The nitrogen gathered by the bacteria within the
nodules on the roots of legumes is absorbed by the roots.

THE FARMER'S BUSINESS 37

earth. In this connection no truer statement was ever made than
that written more than three thousand years ago:

In the sweat of thy face shalt thou eat bread, till thou return unto the
ground; for out of it wast thou taken — for dust thou art and unto dust shalt
thou return. — Gen. 3 : 19.

The Great Work of Plants. — The elements which compose an
animal body are gathered from various sources, and as such they
are only in one of the stages or forms in the cycles through which
they pass. A speck of phosphorus, for example, contained in an
animal body may have been gathered from a cabbage head or a
turnip ; it tarries there for a lifetime, then continues its wanderings
through the ages; and the only way it can again become a " build-
ing block" in an animal body is to become built up in the tissue
of some edible plant.

Plants not only furnish building materials for animal bodies,
but they also supply them with fuel for heat and energy. Thus a
great work of plants is to bring together carbon, oxygen, nitrogen,
mineral elements and water and build them into foods for man
and beast.

The Farmer's Business. —Since man and beast must eat to
live and grow, the farmer's big business is to raise those plants
which have been found good for foods. Not only must he provide
foods but materials for clothing as well. In order that the farmer
might do this most successfully he must understand soils and the
principles upon which crop production depends.

Demonstration. — Materials Needed. — Material and apparatus necessary to
generate and demonstrate characteristics of oxygen, hydrogen and carbon
dioxide gas: Samples of the elements aluminum, calcium, magnesium, sodium,
potassium, phosphorus and carbon; lime, wood ashes, one-fourth of a pound
of dry grass or clover hay, a baking powder can.

1. Object. — To demonstrate the properties of oxygen, aluminum, calcium,
magnesium, sodium, potassium, carbon, hydrogen, lime and carbon dioxide.

2. Object. — To explain the true meaning of potash.

Procedure. — Fill a baking powder can, having a perforated bottom, with
wood ashes and leach out the potash. Evaporate.

3. Object. — To show that plants contain mineral matter.

Procedure. — Burn about 4 ounces of dry grass or clover hay and note
the residue.

Questions. — (a) What are ashes?

(6) Where did this material come from originally?

(c) What escaped during the burning?

(d} What part of clover hay is carbon?

(e) What is the per cent ash content of clover hay?

38 CHEMICAL COMPOSITION OF SOILS

QUESTIONS

1. How may the chemical composition of soils be expressed? Distinguish

between element and oxide.

2. Name the more important elements of which soils are composed. Give

symbol for each. (See table.)

3. In what form do the elements occur in soils?

4. Name four of the soil elements with which you are more or less familiar.

5. Describe the elements calcium, magnesium, sodium, potassium

and phosphorus.

6. Which is the most common and abundant element on the earth? In

the universe?

7. Name the common mineral elements contained in soils.

8. Name the essential elements which crops take from soils.

9. Which elements are most commonly deficient in soils and which affect

crop yields the most?

10. Name the elements commonly regarded as the fertilizing elements.

11. What can you say concerning the amount of the four most important

elements in soils?

12. How is nitrogen held in soils?

13. Of what importance is decay in plant growth?

14. What is meant by lime?

15. Distinguish between potassium and the common meaning of "potash."

Between phosphorus and "phosphoric acid."

16. What is potash?

17. In what two ways are soils of use to plants?

18. How does the chemical composition of plants compare with that of soils?

What are ashes?

19. Name all the elements required in plant growth. What are the sources

of these elements?

20. Do plants take hi nitrogen through their leaves? How then do they get

this element?

21. How do plants get their carbon?

22. What per cent of a corn kernel is carbon? Of clover hay?

23. How does the chemical composition of an animal body compare with that

of plants and the soil?

24. What is a great work of plants?

25. What is the business of the farmer?

26. Compare the amount of wood fuel or coal burned in a stove in your home

with the amount of ashes removed. Explain.

27. For summary of Chapter III in outline form see table of contents.

CHAPTER IV

HOW ROCKS AND CLIMATE AFFECT SOILS

AMONG the factors which determine soil types was mentioned
"kind of material" which refers largely to the kind of rock from
which the mineral particles came. Any traveler interested in
soils can easily observe the marked effects that rocks and climate
have upon soils in different sections of the country. In this chapter
we shall consider some of these effects both from a physical and
chemical point of view in order that we may understand certain
facts and soil conditions that may come within our observation,
experience, or reading.

ROCKS IN THEIR RELATION TO SOILS

Kinds of Rocks and Their Changes. — There are many kinds of
rocks, all of which may be divided into three main groups, according
to the manner in which they were formed.

Igneous rocks were the first to form on the earth. They are
also formed by the solidification of molten material from within
the earth. Lava rocks formed through volcanic eruptions are,
therefore, igneous rocks. , Other igneous rocks are granite, basalt,
and syenite.

Sedimentary rocks are bedded rocks formed from sediments
such as sand, shells, mud, etc., deposited in sheets through the
action of water and wind — mostly through water action. Through
pressure and cementation these sediments gradually change into
rocks; such as sandstone, limestone and shale. Most sedimentary
rocks have been formed under sea water. All materials forming
these rocks came originally from igneous rocks. Sedimentary and
igneous rocks may change into metamorphic rocks.

Metamorphic rocks are so called because they are rocks which,
through long periods of time, have changed their structure as a
result of great pressure, heat, and water solutions. Slate, marble,
quartzite, and schist are examples. A limestone may change into
a marble, which, under proper conditions may further change its
structure and become a schist. Thus a sedimentary rock may
change into a metamorphic rock, and, in turn, may undergo a
further change sufficient to be designated as another kind of meta-
morphic rock; namely, a schist.

39

40

HOW ROCKS AND CLIMATE AFFECT SOILS

A Rock is an Aggregate of Mineral Particles. — On examining
rocks closely we find them composed of mineral particles massed
or cemented together.2 In some rocks, as sandstone, the particles
are mostly of the same kind. In others they are of different kinds.
In a granite, for example, the dissimilar particles may be easily
distinguished by differences in hardness, color and crystal form.
They are called "rock-forming minerals."

Rock-forming Minerals of Many Kinds. — We shall not attempt
to study all the many kinds of minerals of which rocks are com-
posed, but only the more common and important ones as are given
in the following table:

The Common and Important Rock Minerals

Minerals

Relative
abundance
in crust of
earth, %

Elements of which they are
composed (p. 30)

Feldspars .
Quartz . . .
]VIicas

48

35

8
1

8

Si, Al, Na, Ca, K, O.
Si, O.
Si, Al, Na, Ca, Fe, Mg, K, O.
Si, Al, Na, Ca, Fe, Mg, O.
Ca, O, C.
Ca, Mg, 0, C.
Ca, P, O, Fl.
Fe, O.
Fe, S.
Ca, S, O.

Hornblenc
Calcite
Dolomite
Apatite
Hematite
Pyrite
Gypsum

e, angite, etc
all others

A study of the chemical composition of these rock minerals
will make clear to us the source of the mineral elements necessary
for plant growth.

No nitrogen is found in any of these minerals.

Quartz particles are the grains of whicli sandstones are
mostly formed.

Why Some Soils Are Deficient in Some of the Important
Mineral Elements. — A sandy soil composed of quartz sand, or
derived from pure sandstone would naturally contain only a very
small amount of the important mineral elements. Why?

Soils composed of mineral particles derived from rocks contain-
ing such minerals as feldspars, hornblende, micas, apatite, etc.,
are usually well supplied with the mineral plant-food elements.

The fact that peat soils do not contain any appreciable amount

2 Lava or glassy rocks are exceptions.

SALTS 41

of mineral particles containing the necessary mineral ele-
ments explains why they are generally deficient in potassium
and phosphorus.

Muck soils usually contain more potassium and phosphorus
than peats, because these soils contain considerable mineral
matter (Chapter II).

MORE ABOUT WEATHERING

Products of Rocks Weathering. — We have learned that the
framework of mineral soils3 consists of sand, silt and clay — the
common products of rock weathering.

When a granite, for example, is transformed by weathering
into soil, many chemical changes occur during the transformation.
A residual soil from granite is not merely a powdered form of that
rock, represented by a combination of sand, silt and clay. Many
of the soil particles, jt is true, are the same kind of mineral particles
as are found in the granite; others, however, are quite different
from any that ever occurred in the parent rock. The formation
of the new kinds, or secondary minerals, is a result of the chemical
changes, or decay. In the decay, or chemical changes, many of
the complex rock minerals are split up, chemically, and their, ele-
ments recombine in different ways, or unite with other elements,
water and gases.

In addition, therefore, to the common products of rock weather-
ing— sand, silt and clay, there are formed other products, among
which are true clay (kaolin), carbonate of lime, and salts.

True clay (kaolin) is a definite, fine material originating mainly
through the decay of feldspars and micas.

Carbonate of Lime, or lime carbonate, is lime combined with
carbon dioxide gas. (CaO + CO2). It is formed in rock decay
when the calcium (Ca) in the rock enters into a new combination
with and through the action of carbon dioxide and water.

The mineral calcite is a pure form of carbonate of lime. Lime-
stone, shells, coral, marble, dried lime mortar, air-slaked lime and
marl are other forms of material containing lime carbonate.

Salts. — Among the many salts formed during the process of
rock decay are:

Chlorides. — Common table salt is an example.

Sulfates. — Glauber's salt is an example.

3 Soils made up of materials derived from rocks are commonly referred to
as "mineral soils."

42

HOW ROCKS AND CLIMATE AFFECT SOILS

Carbonates. — Such as washing soda.

Phosphates. — As lime phosphate.

From Granite Into Soil. — A residual soil resulting from the
weathering of a granite is usually a sandy loam or loam. The
transformation of granite into soil is illustrated and summarized
in the following diagram :

From Rock into Soil

The rock

lineral composition

Chemical composition of the
rock minerals

Products of
rock
weathering

Resulting soil
(classes)

Quartz

Si, O

Sand, silt,

clay *

Sandy loam

Feldspars

Al, Si, Na, Ca, K, O

True clay

Granite*

Micas
Hornblende

Al, Si, Na, Ca, Mg, Fe, K, O
Al, Si, Na, Ca, Mg, Fe, O

Carbonate
of lime

or

Apatite

Ca, P 0

Salts

loam

Pyrite

Fe,S

* Sand, silt and clay particles are mainly the products of the breaking up of rocks, while
true clay, carbonate of lime and salts are products of rock decay.

Soils From Other Rocks. — Sandstone usually gives rise to sand
or sandy soils; shale and slate to heavy clays, and limestone to
silt loams and clay loams.

THE EFFECT OF CLIMATE

Soils in Humid Climates Are Leached. — In humid4 climates
the heavy rainfall causes much soil to be washed away and carried
into the ocean. Sand, silt and clay are not the only materials
carried into the sea — carbonate of lime and salts are also
thus carried.

In a humid region much of the rainfall sinks into the ground,
and as the water passes down through the soil it dissolves carbon-
ate of lime and salts and carries them in solution until it comes
to the surface in the form of springs; thence into rivers, and finally
into the sea. All drainage waters, therefore, carry to the sea,
carbonate of lime and salts in solution and sediments.

4 When a region has an average annual rainfall of more than 30 inches
it is regarded as having a humid climate. A region having an average annual
rainfall of between 20 and 30 inches the climate is commonly referred to
as sub-humid.

ALKALI SOILS

43

What Becomes of the Materials Carried Into the Sea. — The

sand settles out near the shore, and in time becomes sandstone

(Fig. 17).

The clay settles to the bottom farther out and finally turns

to shale.

The salts remaining in solution become the "salt of the sea."
Shells. — The carbonate of lime is taken out of solution in the

ocean water by myriads of tiny shell animals, whose shells sink to

the ocean floor when they die. Coral animals, certain water

plants and bacteria also cause carbonate of lime to be deposited.

Usually, however, on the sea bottom beyond the accumulations

FIG. 17. — The ocean receives all the materials washed from the continents. The sand
settles out of the river waters near shore, and the clay is carried farther out. The salts
make the sea-water salty. The dissolved carbonate of lime is taken out of solution by
tiny shell animals.

of sand and mud there are deposited shells and particles of carbon-
ate of lime which in time turn into limestone. As a general rule,
whenever limestone, sandstone or shale is found, there at one
time existed a sea or lake.

The mud and sand, which are the impurities of limestone, con-
stitute the soil-forming material when limestone weathers.

Alkali Soils. — Soils in regions of little or no rainfall are not
leached as they are in humid or sub-humid climates. The salts
formed through weathering processes, therefore, accumulate in
these soils. In places the soils are so salty that cultivated plants
cannot grow in them (Fig. 18). Such soils are called "alkali
soils." Salty crusts commonly form on their surfaces. When

44

HOW ROCKS AND CLIMATE AFFECT SOILS

these crusts are white the name "white alkali" is used, and " black
alkali" when the crusts are brown or black. "Black alkali" dis-
solves organic matter; hence the black crusts.

Alkali Spots. — In sub-humid and humid climates small areas
of alkali soils may be found varying in extent from a few square
rods to several acres. These areas are usually depressions or areas
kept wet by seepage water. In either case there has been an
accumulation of salts in these areas, the quantity is usually not
sufficient to prevent entirely the growth of crops; though in some
cases much injury does result.

FIG. 18.— An alkali area in Western United States. Alkali soils like these do not
form in humid regions, because the salts which are formed as a result of rock weathering
are dissolved and carried away. (U. S. Dept. of Agriculture.)

Other Effects of Climate. — Soils in arid 5 and semi-arid climates
are usually coarser textured and generally lighter in color than
those of humid regions.

Arid soils are deep and uniform with but little difference in
texture between soil and subsoil; while those of humid or sub-
humid regions are generally of fine texture and have subsoils which
contain more clay than their surface soils.

5 Sections receiving less than 10 inches of rainfall annually are designated
"arid," and "semi-arid" when the annual rainfall is between 10 and 20 inches.

LEACHED AND SOUR SOILS

45

In cool, humid climates, organic matter decays slowly, hence
soils in such regions are generally well supplied with organic matter.

In warm, humid climates, vegetable matter in soils decays
rapidly, hence the soils are usually low in organic matter. This
accounts in part for the many red soils found in the South and
the Tropics.

Leached and Sour Soils. — Soils in humid regions are generally
well leached of their soluble salts. Moreover, many of them, espe-
cially the upland soils, have had the carbonate of lime so completely
leached out of them that they have developed a condition generally
referred to as " acidity." Soils which lack carbonate of lime are
thus commonly termed "sour" or "acid."

Illustration Material for Lessons. — A few hand specimens of igneous,
sedimentary and metamorphic rocks. (Include a sample of lava rock.) Speci-
mens of the common rock-forming minerals. A sample of kaolin (true clay).
Limestone and other natural carbonates.

If possible show samples representing different stages in the formation of
il from an igneous rock; from a sandstone; shale; and from a limestone.

A sample of an alkali soil and of a red soil commonly found in the South.

Demonstrations. — Material Needed. — A tablespoonf ul each of common salt
id sodium carbonate; 4 tumblers; and about two-thirds of a cupful of a
>lack soil.

To Make Clear the Meaning of " White » and " Black " Alkali— Pro-
cedure.— Place about a handful of black soil in each of two tumblers. Fill
one about half full of a strong solution of common salt (a white alkali) and the
other about half full of a strong solution of sodium carbonate (black alkali).
Stir the contents of each tumbler and let stand at least twelve hours. Strain
the liquid into two other tumblers and note difference in color. (Show the
class samples of the two salts.)

Questions. — (a) Which salt dissolves organic matter and which does not?

(6) What would be the color of the drainage water in a section of "black"
alkali? In an area of "white" alkali?

(c) Why is the one salt called "white" and the other "black" alkali since
both salts are white in color?

(d) Where are alkali soils found? Why?

Laboratory Exercises. — Materials Needed. — Specimens of common rock-
forming minerals — feldspar, hornblende, quartz, white and black mica, calcite,
gypsum, apatite, pyrite, etc.; specimens of common rocks, such as granite,
trap rock, schist, shale, slate, limestone, marble, sandstone and quartzite.

To Learn to Recognize the Common Rock-forming Minerals. — Procedure*.
— Examine carefully the samples of rock-forming minerals provided for study.

Record observations in tabular form with headings as follows: Name of
mineral, color, essential plant-food element it contains, plains in which mineral
can be split (plains of cleavate), common end product in weathering, and rela-
tive hardness.

The relative degree of hardness can be determined by scratching each
with the other. (See Rocks and Rock Minerals — Pirsson.)

Questions. — (a) Which are the two most common rock-forming minerals?

(6) Suppose a sand (soil) contains many sand particles of apatite. What
of its phosphorus supply?

46 HOW ROCKS AND CLIMATE AFFECT SOILS

(c) A muck contains much silt and clay. What of its supply of mineral
plant-food elements?

(d) Suppose the mineral matter in a muck is all quartz sand. Would its
supply of phosphorus and potassium be the same as that of (c)? Why?

To Learn to Recognize the Common Rocks. — Procedure. — Examine with
hand lens the different rock specimens provided. Record observations in
•tabular form — headings as follows: Rock group, name of rock, color, texture,
structure (dense, fine grained, granular, or laminated), and important min-
erals of which composed.

Questions. — (a) What kinds of soil form the following rocks — granite,
sandstone, limestone, and shale?

(6) What forms the soil in the weathering of a limestone?

Field Studies. — When practicable, field trips may be made for studying
the rock formations of the community. Note relation between the prevailing
rocks and the kinds of soil. Note also whether the areas of soil visited are of
residual or transported formation.

QUESTIONS

1. Name the three large groups or classes of rocks. How do these three groups

differ from each other as regards origin? Name some of the common
rocks belonging to each group.

2. Tell of the changes that rock undergoes.

3. What is a rock?

4. Name some of the common rock-forming minerals.

5. What is the source of the important mineral elements required by plants?

6. Why are some sandy soils poor in mineral plant-food elements?

7. Why are peat soils generally deficient in potassium and phosphorus?

8. Do muck soils contain more or less mineral elements than peat? Explain.

9. Name the products of rock weathering.

10. Distinguish between clay and true clay.

11. What is carbonate of lime? Name some materials containing much

lime carbonate.

12. What kinds of soils are formed from granite? From sandstone? From

shale? From limestone?

13. Why is the water of the sea salty?

14. Explain how sandstone, shale and limestone are formed.

15. How can a soil form from a limestone?

16. What are alkali soils? Alkali spots?

17. Name other differences in soils of arid and humid regions.

18. In what kind of a climate are acid soils likely to occur? Explain.

19. Distinguish between "arid," "semi-arid," "sub-humid" and "humid"

climates.

20. In which ones of these have you lived?

CHAPTER V

SOIL AN IMPORTANT FACTOR AFFECTING
PLANT GROWTH

THE growth of plants has interested thoughtful men of all ages.
Little by little knowledge concerning plant growth accumulated,
and even today all is not known. Scientists will always study and
investigate the growth and habits of plants. In order that a clear
understanding might be gained of some of the fundamental
principles of crop production, it is necessary to know a few facts
concerning the growth of plants, and note in particular to what
extent soils may affect this growth.

Conditions Must be Favorable. — It is self-evident that a plant
must have favorable conditions surrounding it before it can grow
to its fullest development. These conditions must be favorable
from the time the seed is planted to maturity.

The life history of a plant may be conveniently divided into
four periods; viz., the seed or dormant period, the germination
period, the vegetative or growing period and the fruition or fruiting
period. The average farm plant passes through three of these
periods in contact with the soil. We shall now consider the con-
ditions and requirements necessary to each of these three periods.

THE GERMINATION PERIOD

The Germination Period a Critical One. — Many poor crops
are to be explained in no other way than that the conditions
during the time of germination were not favorable. Frequently
when the conditions are too unfavorable the seeds become moldy
and fail to germinate.

Life in a Planted Seed Strives for Existence. — When a seed
is planted in the soil it is placed in a medium teeming with bacteria
and fungi which would feed on the seed if no resistance were offered
by it. Thus, as soon as a seed is placed in the ground there begins
at once a struggle for existence on the part of the life in the seed
against these bacteria and fungi. When conditions are favorable
for the seed, it wins and sends out its roots and stem ; if unfavorable,
the soil organisms win and cause the seed to decay. How
.very necessary it is, "therefore, that the conditions be favorable
during germination.

47

48 SOIL AN IMPORTANT FACTOR

Requirements and Conditions for Germination. — For a most
vigorous germination seeds require (a) a favorable moisture supply
in the soil ; (6) sufficient air for oyxgen ; (c) favorable temperature,
and (d) good tilth. It is to be noted that a germinating seed
requires no plant-food elements from the soil or carbon dioxide
from the air. It does not need them, since nature has surrounded
the germ in the seed with a storehouse of food. As soon as the
dormant life quickens, this store of food is drawn upon to nourish
it. Water and oxygen are required for the same reason that ani-
mals require them; viz., for life processes. And warmth is just as
essential in promoting these life processes in a germinating seed
as it is in an animal body.

Just as some animals can tolerate lower temperatures than
others, so it is with germinating seeds. Farmers in different sec-
tions of the country learn by experience when it is the best time
to plant various seeds to meet favorable temperature conditions.
No farmer in a temperate zone would think of planting beans and
corn as the first crops in early spring. Again, corn will rot under
temperature conditions that will permit germination of winter
wheat and rye.

When lands are wet and cold, a farmer can help in a large meas-
ure to create more favorable temperature conditions in the soil
by draining such lands.

The supply of air and moisture and the temperature conditions
for the planted seed are influenced in a large degree by the physical
condition of the soil or seed bed. In this connection much is said
and written concerning tilth.

Tilth Defined. — Tilth refers to the physical condition of the
seed bed with respect to mellowness and firmness, indicating
whether or not the soil is capable of favoring germination or
promoting plant growth.

Good Tilth. — When a soil has a certain degree of mellowness
and firmness favorable to seed germination and plant growth, it
is said to have good tilth; for example, a loamy soil having a fair
degree of firmness.

Poor Tilth. — A soil is in poor tilth when it is too loose, very
lumpy or very hard and compact. These conditions are unfavor-
able to germination and plant growth.

Tilth does not indicate a rich or poor soil. The poorest soil
imaginable may have excellent tilth; a poor sand, for example.

The only substance a germinating seed takes from the soil is

THE PERIOD OF GREATEST ACTIVITY 49

water. Because of this, good tilth is of vital importance since
firmness of the soil determines largely the ease with which the
planted seed secures this moisture.

Absorption of Water by Seeds. — As soon as a seed is planted
in moist soil it begins to absorb water, and as a consequence,
it swells to its fullest extent before it germinates. Some seeds
absorb more than their own weight of water. When other con-
ditions are favorable, absorption of water determines largely the
welfare of the seedling and vigor in after-growth. The factors
which influence the rate of absorption are (a) contact between
the seed and the soil, (6) amount of moisture in the soil, (c) tem-
perature, and (d) salts. These factors may seem unimportant; on
the contrary they have direct bearing on successful farming.

Contact between the seed and soil is the means whereby the
moisture in the soil gets to the seed. The better the contact,
therefore, the better the moisture supply for the seed, provided,
of course, there is moisture in the soil. This explains in part why
a firm seed bed is generally desirable. Alfalfa seed sown in a loose,
ashy seed bed very often results in failure, because of the lack of
good contact between the seed and the soil.

Moisture. — Seeds cannot germinate in dry soil. The planting
of soaked seeds in dry soil invariably results in failure. The more
water in the soil does not necessarily mean a more rapid absorption
and hence a more rapid germination. Too much water shuts out
oxygen and it also creates unfavorable temperature conditions.

Warmth favors and cold retards absorption of water by seeds.
When water absorption is retarded germination also is retarded.

Salts Retard the Rate of Absorption. — Under like condition
seeds will absorb moisture more slowly and hence germinate some-
what more slowly in a rich soil than in a poor one. If present in
considerable amounts, salts act as poisons. Many alkali soils
will not permit germination of seeds. Some salts are poisonous to
plants even in small amounts. Sometimes a farmer greatly retards
germination or even kills his corn seed, for example, by dropping
too much fertilizing salts on the seed in the hills or drills.

THE VEGETATIVE OR GROWING PERIOD

The Period of Greatest Activity. — This is a most active period
in the life history of a plant. During this period the plant carries
on six distinct activities, namely:
4

50

SOIL AN IMPORTANT FACTOR

1. It respires.

2. It transpires — moisture is given off, particularly from
the leaves.

3. It takes in substances (raw materials) : (a) Carbon dioxide,
(6) water,1 (c) salts (containing nitrogen and mineral elements).

4. It converts the raw materials into foods: (a) Protein, (6)
carbohydrates, (c) fats.

5. It grows.

6. It stores foods.

The Plant a Factory. — As soon as the seedling establishes itself
in the soil it shifts its dependence for food from that stored in the
seed by its parent plant to that of its own manufacture. Thus

/7o/es

Fasten**

W/f/7

FIQ. 19. — A plant culture in a fruit jar.

the plant grows into a real manufacturing establishment, most
wonderful and mysterious throughout. The plant cells correspond
to the departments — the leaf cells being the most important; the
content of the cells, chlorophyll,2 etc., represents the machinery;
the raw materials taken in are carbon dioxide, water and salts
(Fig. 19); the power is the energy of sunlight; and the products
are foods, of which there are three classes — protein, carbohydrates
and fats. The common carbohydrates are sugars and starches.

Conditions and Requirements During Vegetative Period. — In
order that the average farm plant might carry on all its activities

1 Only a comparatively small amount of the water taken in by plants is
used in the manufacture of foods — most of it is transpired.

2 Chlorophyll is the substance in plants that gives them their green color.

PERMEABLE SOIL IS IMPORTANT

in the best possible manner, the following conditions and /eqir.e-
ments must be met :

(a) Sufficient moisture must be present in the soil.

(6) The plant must have air from which to secure oxygen and
carbon dioxide.

(c) Favorable temperature must prevail.

(d) The soil must be in good tilth.

(e) The plant must be able to secure sufficient nitrogen and

mineral elements from the soil.

(/) The plant must have sufficient sunlight.

It is to be observed that in this period the plant demands three
other requirements and conditions in addition to those required
during germination; viz., carbon dioxide, plant-food elements
and sunlight.

Temperature in Relation to Crop Growth. — The air temperature
at which plants grow the best varies with different farm crops.
The best for small grains is between 77 and 88 degrees F.; for
cucumbers and melons, between 88 and 99 degrees; for corn and
hemp, between 99 and 1 10 degrees.

The lowest air temperatures at which crops can make some
growth are as follows: for small grains, between 32 and 41 degrees
F.; for corn, between 41 and 51 degrees; for tobacco, between 51
and 60 degrees; and for melons and cucumbers, between 60 and
65 degrees.

Permeable Soil Is Important (Good Tilth). — If the soil covering
a seed should become hard and very compact, the stem may not,
or may with difficulty, succeed in breaking through. If the soil
around and below it also becomes too hard and compact, the roots
are checked in their development — a stunted plant is the result.

If, on the other hand, the soil is in a condition to permit the
stem to push itself through to the surface with ease, and the roots
to penetrate the soil without hindrance, the seedling soon estab-
lishes itself as a vigorous plant. A permeable soil, therefore, is
an important condition, not only when the plant is very small
but throughout its growing period.

Much attention, therefore, should be given to the preparation
of the most favorable condition that will enable a young plant
to establish itself in the soil in the quickest and best possible
manner. This attention is to be confined largely to the develop-
ment of good tilth, or in other words, to the preparation of a good
seed bed. The smaller the seed to be sown, the better the seed-
bed preparation should be (Figs. 20 and 21).

52

SOIL AN IMPORTANT FACTOR

What Good Tilth Implies. — Very often a farmer is deceived in
thinking that the looser the soil or seed bed becomes through

FIG. 20.— The secret in planting garden seeds properly. Place the seeds in a shallow
trench made in a firm, moist seed bed, cover seeds lightly with fine, moist soil, press the
soil on the seeds to secure good contact between the soil and the seeds (C), then cover
with loose soil (D).

FIG.

,„, 21 —The difference it makes. Radish seeds in row A were planted loosely in
moist soil, while those in row B, though planted the same time, were pressed in close con-
tact with the moist soil, as in Fig. 20. This principle in seed-planting applies generally.

plowing and harrowing, the more excellent the tilth or seed bed.
Good tilth does not imply just looseness or mellowness of the seed
bed — it means a certain degree of firmness or compactness as well.

WHAT GOOD TILTH IMPLIES

53

22. — The development and distribution of corn roots in permeable soil under field
conditions. (King.)

54 SOIL AN IMPORTANT FACTOR

The full meaning of good tilth and its importance as regards the
seed and the young plant may be gained by studying the following
brief outline.

{a. Entrance of air.
6. Stem penetration.
c. Root penetration.

Good tilth implies 2 Firmnegs of geed bed to , Between soil particles.

secure good contact (Fig. j 6. Between seed and soil.
20) [ c. Between roots and soil.

Whenever a seed bed is too loose, therefore, it should be made
firm even before planting, by the use of a roller, so that there will
be good contact between the soil particles, between the seed and
the soil when the seed is planted, and later on between the roots
and the soil. The soil should be firm enough to make this good
contact possible, yet not so compact as to prevent the entrance of
air and the easy penetration of the stem and roots (Figs. 22 and 23) .

Factors Affecting the Development of Good Tilth.— The devel-
opment of good tilth through cultivation depends largely on the
texture, structure, and moisture content of the soil. Heavy soils
usually require careful management to secure good tilth. It is not
difficult to develop a good seed bed on sandy and loamy soils,
and on soils having a crummy or granular structure.

A hard and lumpy or heavy clay if plowed in the fall will develop
good tilth of itself as a result of the freezing and thawing during
winter and early spring.

All soils work up much better when they contain a proper
amount of moisture. Plowing or cultivating a heavy soil when
too wet invariably results in poor tilth, in that the soil becomes
hard and lumpy.

Plant-food Elements. — The so-called "raw materials" taken
in by plants contain the essential elements which enter into the
composition of the foods made by them, hence the term " plant-
food elements."

Availability of Plant-food Elements. — Nitrogen and the mineral
elements enter the plants through their roots in the form of com-
pounds or salts in solution.3 These elements must be in the form
of soluble compounds, or in liquid form, before they can become
available to the plants. In this respect we speak of " availability"
of the plant-food elements.

3 Water enters a plant through its roots by a process called "osmosis."
The entrance of salts in solution may be termed "diffusion."

FUNCTION OF THE PLANT-FOOD ELEMENTS

55

When a soil has an ample supply of the necessary elements in
soluble form or in a condition which may be easily converted into
soluble form when needed for the production of a large crop, that
soil is described as having sufficient "available" plant-food ele-
ments for a good yield.

The fact that crop produc-
tion depends in a large measure
upon the availability of the
plant-food elements in the soil
makes it necessary that farmers
understand the . conditions
whereby soils may give up these
elements in the amounts de-
manded by good crops. These
conditions and principles are
discussed in later chapters.

Function of the Plant-food
Elements. — It is of interest to
note briefly the functions of the
elements required by crops.

Carbon is used in the mak-
ing of carbohydrates, fats
and protein.

Nitrogen is used in the
making of protein.

Phosphorus is of much im-
portance in the " filling out"
and development of the grain,
often hastening maturity. It is
also used in the making of
protein. Sufficient available
phosphorus causes young plants
to develop good, strong root
systems.

Potassiun is much needed
by plants to aid in starch and
protein formation. Such crops as corn, sugar beets, potatoes,
alfalfa and clover, therefore, require large amounts of this element.

Calcium seems to be used largely in leaf and stalk development.
It is also regarded as a protective agent, in that it prevents harm-
ful effects of acids formed within the cells.

FIG. 23. — An argument in favor of a deep seed
bed. The desirable type of sugar beet.
. D. A.)

56 SOIL AN IMPORTANT FACTOR

Sulfur enters into the composition of protein.

Magnesium seems particularly necessary for leaf development.

Iron is necessary for chlorophyll formation.

THE FRUITION PERIOD

During this period the plant arrives at its maturity. It
reaches its object of life; viz., the production of fruit or seed to
propagate itself. During this period grains "fill" and harden,
and fruits mature and ripen. This is not a period of food manu-
facture, but rather of translocation of foods from the stems and
leaves to the fruit or seed. Air, moisture and favorable tempera-
ture are the necessary requirements.

Demonstrations. — Material Needed (not including demonstration No. 8). —
About 12 ounces of corn (seed) ; a few wheat kernels, and a few clover, cucum-
ber, oat and bean seeds; 6 tumblers; 1 balance; a tablespoonful or more of
salt; 1 quart of quartz sand; 6 one-gallon crocks; 18 quarts of loam, or silt
loam; and 10 quarts each of rich garden soil and a poor soil of the same class.

To Show That Seeds Absorb Much Water Before They Germinate. —
Procedure. — Weigh out 50 grams or 2 ounces of either corn, beans or small
grain and soak in water for 24 hours. Then wipe off the adhering water and
weigh again. Determine the per cent of water absorbed. (Use weight of dry
seeds as basis.)

To Show That Temperature Affects the Rate at Which Water is Absorbed
by Dry Seeds. — Procedure. — Weigh out two lots of seed of 50 grams or 2 ounces
each. Soak one lot in warm water and the other lot in cold water for about
two hours. Wipe off the adhering water, weigh, and determine the per cent
of water absorbed.

To Show that Salt Retards the Rate of Absorption of Water by Seeds. —
Procedure. — Place one 2-ounce lot of seed corn in fresh tap water, and another
lot in a strong salt solution. Keep all at the same temperature for several
hours. Then wipe the seeds and compare weights.

To Show That no Added or Outside Plant-food Elements are Needed for
Germination. — Procedure. — Plant large, medium and small seeds (corn, wheat,
clover) in pure quartz sand. Keep moist with pure water. Keep in favorable
temperature, light, etc., and note time in which plants appear. Continue
observations until plants die.

Questions. — (a) Name the essential conditions for germination.

(6) Why are not plant-food elements from outside sources needed for
germination?

(c) Why do the lower leaves dry up first?

(d) Will the dry material of the dead plants (roots and all) weigh more
or less than that of the seeds? Why?

(e) Will the amount of ash be greater or less? Why?

To Show the Effect of Temperature on Plant Growth. — Procedure.— Plant
either winter wheat or oats and cucumber seeds in each of two one-gallon
crocks filled with loam or silt loam. Place both jars in a favorable place.
Water. When the plants are well started, place one crock in a well-lighted
place having a temperature between 35° and 40° F. and leave the other jar
in the greenhouse under favorable temperature conditions. Observe results
after 10 days or two weeks.

CORN IN A RICH AND A POOR SOIL

57

To Make Clear the Meaning of " Carbohydrate."— Procedure.— Put a
tablespoonful of sugar into a tumbler; add a little water to make a thick syrup
(keep cool), then add about two tablespoonfuls of sulfuric acid. Note results
(Fig. 24).

Questions. — (a) Where did the carbon come from?

(6) How did the plant get it?

(r) Why is not sugar black since it contains so much carbon?

(d) Of what is a diamond made?
. (e) What is the difference between a diamond and a piece of charcoal?

To Show that a Farmer Must Observe Temperature Conditions When
Planting Different Seeds. — Procedure. — Proceed as in demonstration No. 5,
and plant a few seeds of wheat, beans and cucumbers in each crock. Place
one crock in the greenhouse and the other in a well-lighted place having a tem-

Carbon

FIG. 24. — What happens when the chemically-combined water is withdrawn from
sugar? The carbon in the sugar is set free. Sugar is a carbohydrate = (carbon + water)
= 12 atoms of carbon (C) combined with 11 atoms of water (H2O). In this case the water
was withdrawn from the sugar by sulphuric acid.

perature between 35° and 40° F. Observe results regarding germination
and growth.

Question. — Construct a table showing the best air temperature at which
some of the common farm crops grow the best, and the lowest temperature
at which crops can make some growth.

To Compare the Rate of Germination of Corn in a Rich and a Poor
Soil. — Procedure. — Procure about four quarts of a rich greenhouse soil and
the same amount and kind of poor soil. Allow both soils to warm to the
same temperature. Moisten both and place in two one-gallon crocks. In
each plant about five kernels of corn. Place both in a favorable place, water
when necessary, and observe which plants appear first. Continue observations
until after four or five weeks.

Questions. — (a) Give reason for the difference in germination and
early growth.

(6) Give reason for the difference in growth after four or five weeks.
(Consult text.)

58 SOIL AN IMPORTANT FACTOR

To Demonstrate the Need of Nitrogen and the Six Essential Mineral Ele-
ments in Plant Growth. — Procedure.— Place 50 kernels each of wheat and oats
between moist blotters, and germinate. When the seedlings are well started
transfer the best ones to culture solutions (Fig. 19). By means of pins fasten
at least 3 of each kind of seedlings in each cork. Start four cultures, as follows:

(1) Distilled water, (2) full nutrient solution, (3) nutrient solution with-
out phosphorus, (4) a culture without iron. Place in favorable place and
observe growth.

Prepare full nutrient solution as follows:

Potassium acid phosphate .... 8 grams in Yz liter distilled water.

Calcium nitrate 6 grams in y% liter distilled water.

Magnesium sulf ate 15 grams in Y^ liter distilled water.

Ferric chloride 0.05 grams in Yi liter distilled water.

For use take 50 c.c. of each of the first three solutions and 4 c.c. of the ferric
chloride solution, mix, and dilute to 500 c.c. with distilled water.

For nutrient solution without phosphorus use 10 grams of potassium
chloride instead of potassium acid phosphate.

For nutrient solution without iron omit the ferric chloride solution.

Cover each jar with brown paper. Keep jars full by using distilled water.
Renew culture solution if plants are allowed to grow a long time. Observe
the character of growth and root development.

Laboratory Exercises. — Material Needed. — A handful each of corn, beans,
oats and wheat seeds; 2 tumblers; 18 one-gallon crocks; a small amount of
tincture of iodine; one mortar and pestle; 8 quarts dry fine sand; 8 quarts
moist fine sand; 8 quarts wet fine sand; 4 quarts dry silt loam; 4 quarts
moist silt loam; 4 quarts wet silt loam; 4 quarts black sandy loam; 4
quarts light colored sandy loam; a small amount pulverized muck and lime;
12 thermometers.

To Demonstrate That Oxygen is Necessary for Germination. — Procedure.
— (a) Place some corn, beans and wheat seeds in two tumblers of water.
Change the water in one tumbler each day, but do not change the water in
the other. (6) Plant some corn, wheat and bean seeds in each of two one-
gallon crocks. Maintain favorable moisture conditions in one, and keep the
other soil saturated and flooded with water. Record results.

Questions. — (a) Why cannot seeds germinate in stagnant water?

(6) Why do corn and beans often rot in wet, cold soils?

(c) Why is oxygen necessary for germination?

To Demonstrate the Importance of Good Contact Between the Soil and
the Planted Seed. — Procedure. — Fill a two-gallon crock with a loam and tamp
so as to make a good, firm seed bed. Make two shallow furrows with a stick
and sow radish seeds in each. Cover seeds in one furrow with moist soil, press
soil down on seed, then cover with loose dirt. Cover the seeds in the second
furrow with moist soil but do not press the soil on the seed. (Before preparing
the seed bed see that the soil is moist or contains a favorable moisture
supply, Figs. 20 and 21.) Place the crock in a favorable place — do not water.
Observe results.

Questions. — (a) Why is it necessary to have good contact between the
seed and soil?

(6) What is the meaning of tilth?

(c) What is good tilth?

To Study the Effect Produced When a Clay or a Heavy Clay Loam is
Worked When Very Wet. — Procedure. — Place a cupful of clay or a heavy clay
loam upon a pie tin or saucer. Add sufficient water to form thick mud. Mold
the mud into a ball and allow it to dry out in the sun. Repeat, using a sand.
Note results. (Save hard clay ball for next exercise.)

EFFECT OF COLOR, WATER AND TEXTURE 59

Questions. — (a) What is the result when a heavy soil is plowed too wet?
(6) Why is clay called plastic?

(c) Why does not the sand ball harden like the clay?

(d) What has happened to make the clay ball become so hard on drying
(Look up "puddled soil" in index.)

To Study the Effect of Freezing and Thawing on a Puddled Soil. — Pro-
cedure.— Thoroughly moisten the hard clay ball obtained in the previous
exercise, and freeze it if the weather is cold, or use a freezing mixture. Place
the frozen ball in the sun to thaw out and dry. Note results.

Questions. — Explain why it is good to plow a hard, lumpy soil in the fall.

To Determine the Effect of Salt When it is in Contact with Planted Seeds.
— Procedure. — Fill a one-gallon crock with moist loam and plant 4 kernels each
of corn and oats. On the first pair of seeds (corn and oat) do not put any salt;
on the second one pinch; on the third two pinches; and on the fourth three
pinches of salt. Cover with soil and observe results. Water when necessary.

Questions. — (a) In what ways does salt affect a germinating seed?

(6) Of what importance is this fact to farmers? (See text.)

To Note the Effect on a Plant of Growing it in Darkness. — Procedure. —
Plant corn and beans in each of two one-gallon crocks. Water both, and keep
at the same temperature. Keep one in the greenhouse and the other in a dark
room. Allow the plants to grow for 2 to 3 weeks and then test the leaves for
starch with tincture of iodine. (A blue color indicates the presence of starch.)

Questions. — (a) What did the plants in darkness live on? .

(&) Why is there no starch in the leaves of the plants grown in darkness?

(c) Why are the plants grown in the darkness white?

(d) What is necessary in the manufacture of starch by the plant?

(e) Why is it difficult to obtain a test for starch in the green leaves early
in the morning?

To Note the Effect of Color, Water and Soil Texture on the Temperature
of Soils. — This exercise may be set up and students observe results.

Procedure. — Fill 12 one-gallon crocks within one-half inch of the top as
indicated below. Pack the soils uniformly and carefully, and have crocks
filled to the same mark. This is to be done one day. Set the prepared crocks
where the sun will not strike them and where all will remain at the same
temperature till the next day. Avoid steam pipes.

No. 1. — Fill with water.

No. 2. — Dry fine sand.

No. 3. — Moist fine sand.

No. 4. — Dry fine sand with y± inch of ground muck on surface.

No. 5. — Dry fine sand with Y± inch of powdered slaked lime on surface.

No. 6. — Dry silt loam.

No. 7. — Moist silt loam.

No. 8. — Wet silt loam.

No. 9. — Black sandy loam (dry).

No. 10. — Light colored sandy loam (dry).

No. 11. — Moist fine sand with surface at right angles to sun.

No. 12. — Moist fine sand with surface slanting away from sun.

Put thermometers which were previously tested for uniformity in the
crocks so that the bulbs are 1 Yi to 2 inches below the surface. Do not have the
soil cover them above the 20° mark. Put all the thermometers in at the same
time and read them as soon as they have had time to register. Record results.
Place the crocks in the sun with one side on a strip of board to incline the sur-
faces somewhat toward the sun. (Remember that 11 and 12 have special treat-
ment.) Read the thermometers every 20 minutes for 2 hours. Record results
in tabular form as follows:

60

SOIL AN IMPORTANT FACTOR

Temperature

Treatment

Start

20 min.

40 min.

60 min.

80 min.

100 min.

120 min.

Water only
etc

Questions. — (a) Why does dry soil heat quicker than wet soil?
(6) Why does sand heat quicker than silt loam?

(c) Why are northern slopes preferable for orchards?

(d) Give four reasons why a water-logged soil will not warm up so readily
as a well-drained soil.

(e) How can a farmer aid a low, wet field to warm up quicker in the spring?
(/) Name the factors that influence soil temperature.

Field Studies. — Become familiar with the meaning of tilth and seed bed
by observing soil condition in several selected fields.

Note the temperature of certain well-drained soils, sandy soils, heavy
soils, peat and muck, poorly drained soils, and soil on south and north slopes.

QUESTIONS

Through what periods does

9.
10.

1. Name the periods in the life history of a plant.

it pass in contact with the soil?

2. Why is it important to have favorable conditions surrounding a planted

seed? What are these favorable conditions?

3. Can a farmer ever help to create more favorable temperature conditions

for seed germination and plant growth? How?

4. What is meant by tilth? Good tilth? Poor tilth? Illustrate.

5. Does good tilth imply a rich soil?

6. What is the relation between the absorption of water by seeds

and germination?

7. Name factors influencing rate of water absorption by seeds. Discuss each

8. Which is the period of greatest activity in the life history of a plant?

Name these activities.

How may a plant be compared to a factory?
Name the requirements and conditions necessary during the growing

period of a plant. How do these requirements compare with those of

the germinating period?

11. Discuss temperature in relation to crop growth.

12. What is the importance of permeable soil in relation to the growth and

vigor of young plants?

13. What is the importance of good tilth as regards the seed and the

young plant?

14. Explain how texture, structure and moisture content of soils affect the

development of good ti,lth through cultivation.

15. Why is it good to plow a hard, lumpy soil or a heavy clay in the fall?

16. What is meant by availability of the plant-food elements?

17. What becomes of the carbon taken in by plants? Of the nitrogen?

Of the sulfur?

18. What seems to be the function of calcium in plants? Of magnesium?

Why do plants need iron?

19. Give three reasons why it is important to have a good supply of available

phosphorus in the soil.

20. Explain whv corn, sugar beets and potatoes require much potassium. Do

alfalfa and clover crops need much potassium? Why?

21. What are the requirements of a plant in the fruition period?

22. For summary of Chapter V see the table of contents.

CHAPTER VI

CROPS AS FEEDERS ON THE PLANT-FOOD ELEMENTS

IN THE SOIL

THE elements most commonly studied in relation to crop pro-
duction are nitrogen, phosphorus, potassium and calcium. These
four will receive careful consideration in further study. All crops
are feeders on these important elements and hence they remove
from the soil varying amounts. In this respect a soil actually
gives up a part of itself in producing crops.

Soil Particles Are Not Plant Foods. — It was thought at one
time that crops consumed or digested soil grains, especially the
finest ones.1 This thinking led some of the very early agricultural
writers to advocate the reduction of soil to very fine dust so as to
enable plants to obtain the amount of soil sufficient for good yields.
It was an idea similar to this, no doubt, that gave to the word
" manure" its original meanings, viz., "to till" and "to work
by hand."

Forms in Which Plants Secure Their Elements. — We have
learned that plants secure the elements they require in the form of
carbon dioxide, water and soluble salts. The soluble salts are
derived largely through the decay of organic matter and the
mineral soil particles.

Amount of Elements Removed From Soil by Crops. — The
accompanying table gives the amounts of nitrogen, phosphorus,
potassium and calcium removed by the more common crops.
These amounts are based on crop yields that may be secured
on a productive soil. The amounts contained in the grain,
stalk and straw are given where called for. These figure repre-
sent the averages of many hundreds of crop analyses made in
many laboratories.

It is to be observed that it requires approximately a pound of
nitrogen to grow a bushel of oats or barley, and about one and one-
half pounds per bushel of corn (Fig. 25.)

A fifteen-bushel wheat crop would take from the soil about one-
half the amounts removed by a thirty-bushel crop. The draft
made on the elements by a seventy-eight-bushel corn crop would

1 Jethro Tull's theory— England, 1730.

61

62

CROPS AS FEEDERS

Plant Food Elements Removed by Harvested Crops
(Pounds per acre per year)

Crops

Yield
per acre

Nitrogen

(N)

Phosphorus

(P)

Potassium

(K)

Calcium
(Ca)

Alfalfa hay
Barley, grain
Barley, straw

5 tons
40 bu.
1 ton

(238)
35.3
11 2

23.6
7.1
1 6

185.0
11.8
199

185.0
0.8
46

Barley, total crop

46.5

8.7

31.7

5.4

Beet, sugar (roots)
Blue grass (Kentucky) . . .
Buckwheat, grain

15 tons
2 tons
30 bu.

78.0
53.2

21.8

10.5
9.4
5.5

79.5
70.0
7.3

8.0
12.0
03

Buckwheat, straw

% ton

12.5

0.85

14.1

10.3

Buckwheat, total crop . . .

34.3

6.35

21.4

10.6

Cabbage (heads)

15 tons

105.0

9.2

72.0

36.0

Clover hay, medium red . .
Clover hay, alsike
Clover hay, Japan

2 tons
2 tons
2 tons

(82.0)
(80.0)
(77.6)

6.8
12.0
18.0

54.0
57.5

68.8

61.6
39.2
40.5

Corn, grain .

65 bu.

59.0

9.1

12.0

0.7

Corn, stover*
Corn, cob

1% tons
900 Ibs.

33.0
3.0

6.8
0.3

40.0
4.0

12.2
0.1

Corn, total crop

95.0

16.2

56.0

13.0

Corn (for silage)
Cotton, lint

12 tons
500 Ibs.

81.6
1.5

16.7
0.3

87.5
2.5

14.0
0.6

Cotton, seed

1000 Ibs.

31.5

5.7

9.5

1.8

Cotton, total crop

33.0

6.0

12.0

2.4

Cowpeas hay
Flax, grain
Flax, straw . . .

2 tons
15 bu.
0.9 ton

(124.0)
30.4
20.6

16.4
5.5
1.5

137.0
6.6
15.6

36.0
2.0
9.3

Flax, total crop

51.0

7.0

22.2

11.3

Hemp (dry stalks)
Millet hay (common) ....
Oats, grain

3 tons
3 tons
50 bu.

20.0
80.0
31.7

4.0
9.5
5.6

44.0
107.0
7.4

30.0
16.2
1.1

Oats, straw

1M tons

14.5

2.4

31.1

7.5

Oats total crop

46.2

8.0

38.5

8.6

Onion (bulbs only)
Peas, grain

500 bu.
20 bu.

60.0
44.0

11.0
4.5

52.0
10.1

31.0
2.0

Peas, straw

\}/2 tons

30.0

2.5

26.4

42.3

Peas, total crop

(74.0)

7.0

36.5

44.3

* When corn is shocked in the field weathering causes a loss of elements, especially
potassium, from the stalk and leaves.

RELATION BETWEEN ELEMENTS AND NUTRIENTS 63

Crops

Yield
per acre

Nitrogen

(N)

Phosphorus

d>)

Potassium

(K)

Calcium
(Ca)

Peas, green, total crop ....
Potatoes, Irish (tubers). . .
Potatoes, sweet (tubers) . .

7.5 tons
200 bu.
200 bu.

(85)
42.0
35.0

7.2
6.3
5.0

35.0
53.0
51.0

55.0
2.4

Rye, grain
Rve, straw

25 bu.

1*4 tons

26.5
12.0

4.5
3.0

6.6
16.4

0.5
5.5

Rye, total crop

385

7 5

23 0

60

Soybeans, grain
Soybeans, straw

20 bu.
1 ton

70.0
35.0

7.1
5.4

24.6
32.7

2.2
31.3

Soybeans, total crop

(105)

12.5

57!3

33.5

Timothy hay

2 tons

39 0

54

45 0

100

Tobacco, leaves *

1500 Ibs.

41 0

27

59 0

41 0

Tobacco, stalk

1250 Ibs.

26.0

2.5

33.0

6.8

Tobacco, total crop

67.0

5.2

92.0

47.8

Turnips (roots only)
Wheat, grain
Wheat, straw

15 tons
30 bu.
1.6 tons

60.0
35.6
16.0

13.0
6.8
1.8

72.0
7.9
19.6

15.0
07
4.3

Wheat, total crop

51 6

86

27 5

5 0

* Leaves and stalk containing 30 per cent moisture.

be approximately one-fifth greater than that made by a sixty-five-
bushel crop. In this way we can estimate the amounts of the
elements removed by various yields.

The greater the yields the heavier the draft upon the soil.

The figures in parentheses in the nitrogen column indicate the
total nitrogen content of the legume crops. Much of this nitrogen
is gathered from the air by means of bacteria in the nodules on
their roots.

SOME INTERESTING AND PRACTICAL FACTS CONCERNING THE
FEEDING OF CROPS

Distribution of the Elements in Plants. — As a rule more nitro-
gen is contained in the grain than in the stalk or straw. Phosphorus
goes largely into the grain — the potassium and calcium into the
stalk, straw and leaves. Calcium is found largely in the leaves.

Relation Between Elements and Nutrients. — Crops which
utilize large amounts of nitrogen are rich in protein. (Compare
the preceding table with the table of nutrients in the appendix.)

64

CROPS AS FEEDERS

Crops requiring large amounts of potassium are usually rich
in protein or carbohydrates.

Crops which require much calcium are rich in protein — alfalfa
is a good example.

Crops Vary in Their Needs of Plant-food Elements. — Crops
vary in their requirements of the important elements. Cabbage,
sugar beets, tobacco, alfalfa and corn are some of the
" heavy feeders."

Fia. 25. — A soil actually gives up a part of itself in producing crops. All crops remove
nitrogen and mineral elements from the soil.

Wheat requires more nitrogen and phosphorus per bushel than
oats. It is interesting in this connection to mention that wheat
stands up much better on a comparatively rich soil than oats.

It is better to grow such crops as potatoes, corn, sugar beets
or cabbage on land heavily manured or rich in nitrogen than to
attempt to grow oats. Under such conditions an oat crop lodges
badly. It is difficult to prevent lodging of grains on some soils.

Lodging of Grains. — Lodging is explained on the theory that
the crops do not secure nitrogen and the mineral elements in the
proper proportion. A large amount of easily available nitrogen,

TIMOTHY NOT A "SOIL ROBBER" 65

together with a comparatively low amount of available mineral
elements in a soil invariably causes lodging of small grains. Too
much nitrogen produces rank growth, much leaves and weak straw.
It is not easy to overcome such conditions. It is good farm practice
to try to prevent such conditions by maintaining in the soil a good
supply of easily available mineral elements as well as a good nitro-
gen supply.

Alfalfa a " Heavy Feeder." — Much is said concerning alfalfa
as a great soil enricher. Many believe that it takes only a small
amount of the elements from the soil, and that somehow the more
alfalfa is raised the richer the soil becomes in every respect. The
fact is that in a year a five-ton alfalfa crop removes from the soil of
one acre five and one-half pounds more phosphorus, one hundred
thirty pounds more potassium and one hundred sixty-eight pounds
more calcium than a sixty-five-bushel corn crop. It is not sur-
prising, therefore, that alfalfa should require a rich soil, and that it
fails on a poor soil.

It is believed by some that alfalfa draws most of the mineral
elements from the deep subsoil. In deep and porous soils con-
siderable phosphorus and potassium, no doubt, is brought up from
the deep subsoil; but in a soil having a heavy, silty clay or clay
subsoil beginning a few inches below the surface it is doubtful
that very much available mineral element is present to be ab-
sorbed by the deep alfalfa roots. The fact remains, however,
that when the seven or eight inches of surface soil is poor,
alfalfa cannot be grown successfully without heavy fertiliza-
tion. The reason for this is explained in the fact that most of
the fibrous, feeding roots are to be found in the surface soil. The
roots which penetrate the deep subsoil secure a good water supply
for the alfalfa.

In one respect the growing and feeding of alfalfa on the farm
does enrich the soil, viz., in nitrogen. This can be said of
all legumes.

Timothy Not a " Soil Robber." — It is a common belief that

timothy is "hard on the land." In studying the preceding table,

we observe that this crop does not draw heavily upon the soil.

No doubt timothy got its mean reputation in this manner : When

a field no longer will grow profitable crops of grain or corn as a

result of exhaustive cropping, it is seeded with timothy, because

" it is usually a sure crop, not easily killed out, and it may be grown

several years on such land without much attention being given to it.

5

66 CROPS AS FEEDERS

Because its draft upon the soil is comparatively light and since it
is able, because of its well-developed root system, to draw the
last trace of available elements from the soil, this crop yields from
fair to good even though the soil is too poor for other crops. In
time, however, even timothy will yield poorly. The sod is plowed
up, and if not manured, the crops on this poor timothy sod are
scant. Farmers have often observed that when a field is sown
half to clover and the other half to timothy, and both sods are
plowed, manured and planted to corn, the corn on the clover sod
is much the better crop. Since these facts have been generally
observed, it is inferred that timothy must be a "soil robber."

It is true, nevertheless, that clover is a much better crop to
grow because of its higher feeding value, and because it can gather
nitrogen from the air by means of bacteria that live in the nodules
on its roots.

Some Plants Have Strong Feeding Powers. — It has been
demonstrated that some crops, better than others, can secure their
requirements of mineral elements from insoluble substances in
the soil. Buckwheat, for example, can secure its need of phos-
phorus from soils low in available phosphorus better than oats,
corn or millet. Perhaps this explains why buckwheat does so well
on poor or exhausted soils, and why it is a good crop to grow to
plow under as the first step in the improvement of such soils.

In general, a plant that can grow well on poor soil may be
regarded as having a strong feeding power, while a plant that can
not grow well except on a very rich soil may be regarded as having
a weak feeding power.

Barley Requires a Richer Soil Than Oats. — When we compare
the amount of the elements required by average good crops of
barley and oats, we find but little difference. A soil capable of
producing forty bushels of barley per acre would easily produce
from sixty to sixty-five bushels of oats. In that case the oats
would draw heavier upon the soil than barley. Nevertheless, it is
generally recognized that a richer2 soil is required to grow common
barley than oats. For an explanation we must study the habits
of these two crops.

Barley does not develop so extensive or deep a root system as
the oat, and hence draws on less soil for its needs. It also has
a weaker feeding power and it matures earlier. Thus barley

2 A rich soil is understood to mean a soil having a good supply of available
plant-food elements, as indicated by good crop growth.

FERTILIZER NEEDS BEST DETERMINED BY TESTS 67

must get its necessary amount of plant-food elements from
less soil with less ease and in less time than oats. A richer
soil, therefore, is necessary for barley to enable it to secure
its requirements.

Fertilizer Needs Best Determined by Tests. — Since the table
gives the amounts of the important plant-food elements actually
contained in crops harvested, it is useful in showing the draft that
harvested crops make on soils. The figures are not to be taken to
indicate exactly how much and in what proportion the fertilizing
elements, in the form of fertilizers, should be supplied to crops
growing on any particular soil. The only sure way to determine
the fertilizer needs of any crop on a particular soil is by fertilizer
tests — f or the following reasons :

1. The condition of the soil with respect to the " availability "
of the elements is difficult to determine by chemical analyses.

2. The feeding power of certain plants may not be well
understood.

3. Some plants vary in their chemical composition and hence
in their requirements of some of the elements at different stages
in their growth. Corn and potatoes, for example, contain the most
potassium when well matured, while wheat contains the most
when just heading out.3 Thus the potassium content of a corn
crop when cut is a very good index of the potassium needs of corn,
whereas the potassium content of a harvested wheat crop does not
indicate the true potassium requirements of that crop.

It has been found that a turnip crop requires much more phos-
phorus during its growth than is indicated by its chemical compo-
sition at harvest time.

4. Some harvested crops consist of the entire growth, while
others consist only of the edible or usable portion. This fact must
be remembered when the table is studied. For, example, in com-
paring a twelve-ton corn crop and a fifteen-ton sugar beet crop,
it would appear that the corn crop is the greater feeder on all the
elements. The corn crop consists of the entire growth; the sugar
beet crop only the marketable roots. In case of the fifteen-ton
beet crop at least 6.2 tons of green leaves and tops are left on the
field, containing about forty pounds of nitrogen, 6.5 pounds of
phosphorus, 12.5 pounds of potassium and 30.5 pounds of calcium.
Thus to grow a fifteen-ton sugar beet crop the soil on each acre

3 The amount not needed in later growth or development goes back into
the soil, either washed from the leaves or migrates through the roots.

CROPS AS FEEDERS

must give up one hundred eighteen pounds of nitrogen, seven-
teen pounds of phosphorus, ninety-two pounds of potassium and
38.5 pounds of calcium.

In case of a fifteen-ton cabbage crop, at least eleven tons of
material are left on the field. Thus a fifteen-ton cabbage crop
requires for its production approximately one hundred eighty
pounds of nitrogen, sixteen pounds of phosphorus, one hun-
dred twenty-five
pounds of potas-
sium and sixty-
two pounds of
calcium.

In case of
hemp, it would
seem that a soil
needs to give
up only small
amounts of the
elements to pro-
duce a good crop,
and that it ought
to grow well on
poor soils. On the
contrary, it re-
quires a fertile soil
to grow a good
crop of hemp.

Root Systems
of Crops Differ.—

FIG. 26.— Root-hairs are the absorbing portion of plant Some plants have
roots. These root-hairs come into intimate contact with the soil. /v.,.i.£kr.a:,,£k QT1.J -n^ll
A, root-hairs of mustard plants, with soil adhering and with soil eXLeiJbWe d,nu Wei

we™kJeilterfi' (After Sachs') wheat' when **** youns' and four developed root sy-
stems enabling

them to draw plant-food elements and water, particularly, from
large volumes of soil (Figs. 26 and 27) . Corn and alfalfa are typical
examples. Such crops as onions, cabbage and beets have much
less extensive root systems.

It is the nature of some plants to develop fibrous and much
branching roots largely in the tilled portion of the ground — these
are commonly called shallow rooted plants.

Farm Plants are Interesting Subjects for Study. — In the

PLANT-FOOD ELEMENTS REMOVED 69

preceding paragraphs the importance of plant study is emphasized.
If anyone wishes to grow any kind of a crop most successfully
he should become familiar not only with the best cultural methods
in growing it, but, as far as possible, with all its habits and charac-
teristics as well.

-1

FIG. 27. — The root-hair in the soil, hh, root-hair; e, portion of main root; 1, air space;
2, soil grain; 3, water film. (After Sachs.)

Plant-food Elements Removed by Fruit Crops. — It is of interest
to note the amounts of elements removed from the soil by some
of the common fruit crops. The following table has been prepared
from all available data :

Plant-Food Elements Removed by Fruit Crops
(Pounds per acre)

Fruits

Average
annual yield
per acre

Number
trees
per acre

Nitrogen
(N)

Phosphorus
(P)

Potassium
(K)

Calcium

(Ca)

Apples . .

100 bbls.

50-100

13.8

2.0

14.5

1.0

Cherries

(300 bu.)
300 cases

108

16.0

2.6

16.6

1.0

Peaches
Pears
Plums .

(150 bu.)
450 bu.
500 bu.
250 bu

100
75
100

19.2
10.2
21.7

4.1
1.6
3.6

32.7
19.1
25.7

1.7
1.8
2.0

Raspberries. . .
Strawberries . .

3000 qts.
6000 qts.

10.0
13.5

1.7
4.5

10.0
22.5

0.6*

Strawberries need but little calcium, even in leaf and stem development.

70

CROPS AS FEEDERS

Fruit cannot be produced without the formation of leaves and
new wood. This requires additional amounts of the plant-food
elements — between twenty and fifty pounds of nitrogen, two to
four pounds of phosphorus, ten to twenty-five pounds of potassium
and twenty-five to eighty pounds of calcium per acre.

THE SUPPLY OF NITROGEN, PHOSPHORUS AND POTASSIUM IN SOILS

Having studied the draft that crops make upon the important
elements of the soil, let us now consider the soil reserve or supply
of these elements. Since calcium and lime are fully discussed in
relation to acid soils in Chapter XIII, our attention here is directed
to nitrogen, phosphorus and potassium.

Supply Varies in Different Soils. — It is to be expected that
chemical analyses should show great variations in the amounts
of nitrogen, phosphorus and potassium contained in different classes
and types of soils mentioned in Chapter II (Fig. 28). The amounts
of these elements in any particular soil expressed in terms of per
cent mean nothing or very little to the average person when he
has no standard for making comparisons.

Simple Standards for Comparing Soils. — The following table,
based on the averages of many analyses, will be of much help to
the beginner in judging soils of similar classes and types when
only chemical analyses are given.

The Supply of Nitrogen, Phosphorus, and Potassium in Soils

Soils

Per cent

Pounds per acre 7 inches deep

Nitrogen

(N)

Phosphorus

(P)

Potassium

(K)

Nitrogen

Phosphorus

(P)

Potassium

(K)

Productive silt
loam or clay
loam

0.25
0.08
1.00

3.00

0.1
0.02
0.1

0.12

2.0
0.5
0.75

0.3

5,000
2,000
10,000

15,000

2,000
500
1,000

600

40,000
12,500
7,500

1,500

Poor sand

Muck (average)
Peat (well de-
composed) . . .

Some soils may be rich in one or two of these elements and poor
in others.

It is not to be inferred that a silt loam is not a productive soil
unless it contains at least one-quarter of one per cent nitrogen,
one-tenth of one per cent phosphorus and two per cent potassium.

SUBSOILS CONTAIN PLANT-FOOD ELEMENTS 71

There are many productive silt loams that do not contain such
reserves as here represented. It is well, to be sure, to possess a
farm of silt loam having a supply of plant-food elements at least
equal to that contained in an average, productive silt loam; or a
sandy farm having soil analyzing much better than a poor sand.
And it is more encouraging to possess peat that analyzes 0.15
per cent phosphorus and 0.5 per cent potassium than it is to have
peat containing 0.07 per cent phosphorus and 0.2 per cent potas-
sium. The cropping possibilities of a soil are greater when the
supply of plant-food elements in it is good.

Per Cent not the Best Basis for Comparing the Supply of Plant-
food Elements in Soils. — When we compare the per cent in the
table on page 70, we see that average peat contains twelve times
the amount of nitrogen contained in a productive silt or clay loam ;
but when we compare the amounts in pounds per acre seven inches
deep, we find the comparison to be only three times. It is to be
further observed that peat shows a higher per cent of phos-
phorus than silt loam; but in an acre seven inches deep of peat
there are only 600 pounds of phosphorus while in a silt loam there
are 2000 pounds. The explanation of this lies in the fact that
soils vary a great deal in weight. In round numbers an acre of
each of these soils seven inches deep weighs when dry as follows :

Sand 2,500,000 Ibs. Muck 1,000,000 Ibs.

Silt loam or clay loam . . . 2,000,000 Ibs. Peat 500,000 Ibs.

Peat Soils are Deficient in Potassium and Phosphorus. — In

comparing the supply of plant-food elements of soils on the " pounds
per acre" basis, we observe that peats are abundantly supplied
with nitrogen, but are deficient in potassium and phosphorus
(see Chapter IV). We can now fully understand why these soils
require mineral fertilizers, viz., potash and phosphates.

Peat Lands are Sometimes Deceptively Advertised. — To him
who is unfamiliar with soils, a comparison of the per cents of the
plant-food elements contained in them seems a reasonable basis
for judging their agricultural values. A drained peat analyzing
three per cent nitrogen and 0.1 per cent phosphorus may seem
to him as good if not better soil than a prairie loam analyzing 0.26
per cent nitrogen and 0.08 per cent phosphorus. Such a compari-
son is often used in advertising peat lands. It is well, therefore,
to secure full information before investing (Fig. 28).

Subsoils Contain Plant-food Elements. — It is important to
bear in mind that subsoils also contain the important elements.

72

CROPS AS FEEDERS

In general, the surface soil contains more nitrogen than the subsoil,
owing to the presence of more organic matter. Some deep, black
soils may have as high a percentage of nitrogen in the subsoil
(to a limited depth) as is contained in the surface stratum.

The percentage of phosphorus in the surface layer is conmonly
greater than or equal to that contained in the subsoil. There is
often a close relationship between the phosphorus content and the
amount of organic matter in mineral soils. This accounts for
the higher phosphorus content of the upper strata. During the
virgin state the roots of grasses and other plants brought up
considerable phosphorus from the subsoil from a depth of about

The new analysis, as compared with the
average of 100 fertile soils of Illinois, shows
as follows and shows better than our own
original analysis:

Average
% Wis.

Nitrogen 1.25

Potash 75

Phosphates 14

The re
of tl

Average

% 11.1.

.30

.25

.24

FIG. 28. — How some peat land was advertised. This particular Wisconsin peat was
compared with the best Illinois prairie soil, which averages about 0.25 per cent nitrogen,
1.8 per cent potassium and 0.08 per cent phosphorus.

two or three feet, and this became stored in the organic matter
accumulated in the top soil. On exhaustive cropping, the higher
phosphorus content of the surface soil is gradually reduced until
it equals at least the percentage contained in the subsoil.

The potassium content is usually greater in the subsoil, espe-
cially when they are fine textured. More potassium is found in
subsoils in humid climates because of the presence of more fine
particles which are not only richer in potassium than the coarser
surface particles, but which absorb much of the potassium leached
down from the surface stratum.

In arid and semi-arid soils the phosphorus and potassium con-
tent of the surface soil is very much the same as that of the subsoil,

QUESTIONS 73

Since roots extend into the deeper layers of soil, the subsoil is
to be regarded as a portion of the feeding ground for crops. Sub-
soils which are porous, permiting air to enter freely, may contribute
considerable amounts of plant-food elements to crop needs. The
fact that in humid climates most feeding roots are to be found
in the tilled portion of the ground, especially in the heavier soils,
explains why the draft upon the surface layer is much greater.

Exercises. — Compare an average yield of one of your local crops with
the table of plant-food elements removed, and determine; the amount and value
of plant-food elements removed from one acre.

2. Minor crops may be considered also.

Projects in Crop Adaptations. — On a given field lay off small strips along
one side where the soil is probably of average fertility. On these strips grow
several useful crops as oats, barley, rye, wheat, buckwheat, millet, sorghum,
corn, cowpeas, soybeans or others. Compare them in growth, yields, and study
their probable needs. Keep careful records and notes and from the trials
determine what crops are best suited to the soil.

Buckwheat Project. — Try the growth of buckwheat on poor soil and thus
decide whether it would aid in production of green manure for the improvement
of that soil.

Projects on Poor Soil. — Compare the growths of barley with oats on
poor soil. Determine which requires the richer soil for good returns.

2. In like manner compare barley with rye, and compare oats with rye.

3. Any one of these as barley (or other crops) should be grown on both
rich and poor soil. This will demonstrate the needs of the crop.

Field Studies. — Make studies of soil conditions in a field where grain
lodges badly.

2. Collect whole plants of a number of grasses, legumes, grains, etc.
Compare their root systems to determine this depth of feeding.

QUESTIONS

1. Name the elements most commonly studied in relation to crop production.

2. Are soil particles plant foods? What was taught at one time?

3. In what forms do plants secure the elements they require?

4. How much nitrogen, phosphorus, potassium and calcium is removed from

one acre by a 65-bushel corn crop? By a 50-bushel oat crop?
By a 1500-pound tobacco crop? Which of these crops require the
most calcium?

5. A man grew the following crops on an acre: 1st year, cabbage yielding

15 tons; 2d year, corn yielding 12 tons; 3d year, barley yielding 40
bushels. How many pounds each of nitrogen, phosphorus and potas-
sium were removed from that one acre during those three years? How
much if there were 20 acres?

6. A ten-acre field was cropped three years as follows : 1st year, sugar beets

averaging 12 tons per acre; 2d year, wheat averaging 25 bushels; 3d
year, corn yielding 52 bushels per acre. How many pounds of each of
the important elements were removed from this field during these
three years?

7. How much nitrogen is required to grow a bushel of corn? A bushel of oats?
In what part of crops is found the most phosphorus? The most potassium?

The most calcium?

74 CROPS AS FEEDERS

9. What per cent of the total phosphorus in a wheat crop is lost to the soil
on the farm when wheat is sold? What per cent of the potassium is sold?

10. What is the relation between the nitrogen requirement and the protein

content of crops? Illustrate. What relation is there between the carbo-
hydrate content and the potassium requirement of crops?

11. Name some crops that draw heavily upon the plant-food elements. What

are the elements required by tobacco in large amounts?

12. A farmer says that wheat stands up better than oats on a field formerly

a hog pasture. Explain why.

13. When grain lodges badly what crops should be grown instead?

14. What causes lodging of grain, and how may it be prevented?

15. Discuss alfalfa growing in relation to poor soil.

16. Is timothy more of a "soil robber" than oats? What do you think of

tobacco as compared with corn in this respect?

17. Why can buckwheat and rape grow very well on poor soils? What indi-

cates a strong feeding power in some plants? Weak feeding power?

18. Explain why barley requires a richer soil than oats. What is the meaning

of "rich" soil?

19. How can the fertilizer needs of any crop on any soil be best deter-

mined? Why?

20. Construct a table showing the amounts of "N," "P," "K" and "Ca"

required to grow a 12-ton corn crop, a 15- ton sugar beet crop, a 15- ton
cabbage crop and a 300-bushel apple crop. (See tables.)

21. How do the root systems of crops differ?

22. What are root hairs? Explain their function (Figs. 26 and 27).

23. What knowledge is necessary to grow a crop most successfully?

24. What is the nitrogen, phosphorus and potassium content 01 an average

productive silt loam, expressed in per cent? What can you say of the
cropping possibilities of soils well supplied with plant-food elements?

25. Why is not the per cent basis the best for comparing the amount of plant-

food elements in soils?

26. Why do peat soils require potash and phosphate fertilizers?
27.' How may peat lands be deceptively advertised? Illustrate.

28. Tell of the nitrogen, phosphorus and potassium contained in subsoils.

29. What colors of soil and of subsoil have you seen?

30. See outline summary of this chapter in table of contents.

CHAPTER VII

CROP PRODUCTION AND SOIL FERTILITY

Factors in Crop Production. — Successful crop production
depends upon five factors, viz. :

(1) Fertile soil. (2) Good seed. (3) Favorable temperature.
(4) Light. (5) Protection from injury.

Fertile Soil. — Good soil is a fundamental factor. Not only
should the soil be well drained and cultivated, but it should possess
all the qualities, properties and conditions which impart to it pro-
ductive power. The adjective " fertile" is commonly used in
describing such a soil.

It is not always possible to select fertile soil. Sometimes only
a portion of a farm is productive. Sometimes the soil of a farm is
ind, sometimes peat, and sometimes it consists of several kinds,
and poor. Happily it is within the possibilities of any thinking
ler to transform a poor or unproductive soil into a productive
le; and he is a public-spirited man, indeed, whose ambition it is
bring about such a transformation.

What Makes a Soil Fertile. — The qualities, properties and
mditions which impart productive power to a soil are as follows:
(a) A Suitable Moisture Supply. — Without water nothing can
)w. Many lands have been turned from deserts into gardens
st by the addition of water through irrigation. Very frequently
>ps even in humid climates and on good soil are much reduced,
fail entirely because of drought. Sometimes there is too much
in the soil — for this reason wet lands must be drained
fore they can be made to grow any crop at all — excepting
did hay.

(6) Plenty of Air in the Soil. — Air in the soil is essential to
ivor root growth, to favor the development of the helpful
>il organisms and to enable the necessary chemical changes to
ike place.

(c) Good Tilth. — It is important that the physical condition of
the soil should be such as to enable the young plants to get the
.best possible start — to become quickly and firmly established in
the soil and to favor their development (Chapter V).

75

76 CROP PRODUCTION AND SOIL FERTILITY

(d) The presence of helpful soil organisms of which there are
several kinds; viz., bacteria which cause the formation of the
nodules on the roots of legumes; bacteria, molds and fungi which
help make plant-food elements available, and are helpful in other
ways. Angleworms may also be mentioned in this connection.

(e) A good supply of available plant-food elements from which
crops may secure sufficient nitrogen, phosphorus, potassium,
calcium, etc., to permit of good yields.

(/) The absence of harmful agents in the soil, such as poisons;
too much salt, such as alkali ; certain diseases ; too much water, etc.

These factors are further discussed under "soil fertility," and
in the following chapters.

Good Seed. — It is generally recognized that good seed is a
factor of much importance. Poor seed in poor soil means miserable
failure. Good seed in poor soil renders just as little, if not less,
for labor than poor seed in good soil. But the best combination is
good seed in good soil.

The emphasis put on good seed in agricultural development
today leads some to think that this idea is a product of the twen-
tieth century. Not so. Early agricultural writings reveal the
fact that the value of good seed was much discussed in the old
countries hundreds of years ago. The following quotation, taken
from a book, "Way to Get Wealth/' by G. Markham, printed in
London in 1660, is interesting in this connection :

"... You shal then take your Seed which would be the finest, cleanest,
and best Wheat you can provide, and after the manner of good Husbandry,
you shal sow it on the ground very plentifully, not starving the ground for
want of Seed (which were a tyrannous penury) nor yet choaking it with too
much (which is as lavish a foolery) but giving it the full due, leave it to the
earth and Gods blessing."

Factors Involved. — In spite of the fact that much has been
said and written in this generation about good seed, there
are still many who fail to give this factor any serious con-
sideration. A high germination test is not the only indica-
tion of good seed. There is also involved a selection of size of
seed, and for adaptability, purity, disease resistance, high yield
and superior quality.

Size and Weight. — There is a decided advantage in the use of
large or heavy seeds over small ones, even though they may be of
the same variety and all of high germination test. The Ontario
Agricultural College (Canada) produced a seven-year average of

LIGHT 77

sixty-two bushels of oats per acre from large seed and only forty-
seven bushels from small seed. Both the small and large seed were
selected from the same stock each year.

Disease Resistance. — The Wisconsin Station has developed a
variety of cabbage resistant to the disease of " yellows" (Fig. 165).
Much work has already been done by investigators in developing
disease-resistant plants.

Seed Improvement. — The Cornell Station of New York has
demonstrated a yield of 3.57 tons of timothy hay per acre with
improved varieties as compared with 2.04 tons with ordinary
timothy. The test was made on the same kind of soil and with seed
of equally high germination test. This is a seventy-five per cent
increase in favor of improved varieties. The quality of hay was
also much better.

As a result of working on the increase and decrease in protein
and oil content of corn, the Illinois Station developed from a single
variety of corn in ten years' time, one strain containing 65 per cent
more protein than another, and a third strain containing 177 per
cent more oil than a fourth strain.

These are but a few of many examples illustrating the possi-
bilities of good seed and the advancements that are being made in
improving varieties.

Favorable Temperature. — The temperature at which plants
make their best growth varies with different farm crops. In
diversified farming there is no weather but what is good weather,
since when it is unfavorable for one or two crops it is favorable
for the others. A hot sun, though favorable for corn, often causes
injury to the Irish potato in " burning" the leaves (sun-scald).
Cool and moist weather during the fore part of a growing season
is favorable for grains, but unfavorable for corn. Our poor corn
rears are usually the result of cold, wet weather during the summer
id fall months. Excessive heat and much dampness generally
cause much damage to grains in favoring the development of leaf
and stem rusts.

Since weather is beyond the control of man, except under
artificial conditions, the best that a farmer can do is to plant his
seed at such time as to enable the respective crops to take advan-
tage of the favorable temperature conditions. In this the farmer
is guided in his activities largely by the average weather of his
section or locality (Chapter V).

Light. — In Chapter V we learned that sunlight is necessary for

78 CROP PRODUCTION AND SOIL FERTILITY

plants as the source of energy in the manufacture of foods. Under
field conditions duration of light seems more important than inten-
sity. Some plants require much sunlight while others do better
when shaded. Crops which manufacture much starch and sugar
require much sunlight. In order to increase the succulence and
delicacy of such crops as asparagus, cauliflower, celery, lettuce
and radish, they are sometimes grown under half-shade. In case
of cauliflower more desirable heads are produced through shading
brought about by bringing together and tying the leaves in the
form of a head. Shading is employed in forcing rhubarb, in
ginseng culture, and has proved of much importance in pineapple
culture in Florida.

The sugar beet is a crop requiring abundant sunlight together
with plenty of moisture, especially during early growth. These
conditions are found most favorable in the irrigated districts
of the Rocky Mountain and Pacific States — hence in these
districts the sugar content of beets is usually higher than those
grown elsewhere.

Shading a Factor in Weed Killing. — Many have experienced
much difficulty or failed entirely in trying to establish a lawn under
heavy shade, even when all other conditions were favorable. Lack
of sunlight under such conditions is the cause of failure. Weeds
may be killed through the use of so-called " smothering crops.''
These are fast-growing crops which quickly rise above the weeds
in thick growths, and in so doing shut out the sunlight from the
weeds beneath.

It is commonly observed that a field growing a cultivated crop
after good clover or alfalfa sod is exceptionally free from weeds,
except when weed seeds have been introduced through manure
application. The explanation of this lies mainly in the fact that
the thick growth of clover or alfalfa killed the millions of small seeds
which started to grow, mainly by depriving them of sunlight.

Weeds May Smother Crops. — Many a seeding of alfalfa, or
planting of potatoes, for example, has produced no returns because
weeds were allowed to get ahead of the young plants, and thus
they were robbed of sunlight as well as of moisture and plant
food elements.

One Crop May Deprive Another of Sunlight. — Lodged grain
usually kills out the grass seeding. This killing is due mainly to
the exclusion of sunlight. It is very important that seedings of
clover and alfalfa, in particular, should not be entirely robbed of

SOIL FERTILITY DEFINED 79

sunlight by too thick growth of grain. Clover and alfalfa seedings
arc generally more successful when the nurse crops are not sown
too heavily. A less amount of grain sown per acre enables the
young seeding to get more sunlight. When nurse crops are drilled
in a north and south direction, much more of the midday sunlight
reaches the young clover or alfalfa, thus insuring a better stand
of the hay crops than when the nurse crops are drilled east
and west, or sown broadcast. This is especially true in the
northern states.

Protection From Injury. — A farmer may be defeated in his
plans for raising good crops if he fails to protect them, if need be,
from injury by animals, birds, flood-water, weeds; from injury by
insects, as beetles, worms and aphids which feed on the foliage;
from damage through lodging (smothering the seeding) ; and injury
by diseases as smut, scab, blight, and if possible, by certain rusts.
Proper fencing may be an important consideration in protection,
likewise poison bait for rodents and grasshoppers, spraying,
treating grain and onion seeds for smuts and seed potatoes for
scab, killing weeds by cultivation, getting rid of surplus water
by proper drainage, etc.

SOIL FERTILITY

Productive soils are commonly described as " fertile," also pro-
ductivity of such soils is most commonly referred to as " fertility."

Before proceeding further it is important to have a clear idea
of the meaning of fertility. In the first place the word " fertility"
is but the noun form of the adjective " fertile," and hence carries
the same general meaning.

Soil Fertility Defined. — Fertility means "state or quality of
being fertile; f ruitf ulness ; productiveness." Soil fertility1, there-
fore, is to be interpreted to mean the power of a soil to produce
good or large yields.

To maintain soil fertility means to maintain productivity.

To increase fertility means to increase the productive power of
a soil, or to cause it to produce still better yields.

A soil is said to have lost its fertility when it ceases to be pro-
ductive, or when it no longer possesses the ability for producing
good yields (Fig. 29).

Fertility does not mean the ability of a soil for producing the

1 E. J. Russell, Soil Conditions and Plant Growth.

80

CROP PRODUCTION AND SOIL FERTILITY

highest possible yields. We can speak of degrees of fertility in a
similar sense as degrees of richness, for example.

Very fertile soil or very high fertility implies a very high pro-
ductive power. Low fertility implies that the yielding power is
not very good. " Infertility" means the lack of productive power.

Fertility as applied to a soil in Wisconsin, for example, does
not imply that that soil has the ability for producing good or high
yields of all kinds of crops to be found in the world; but it has
meaning only in relation to those crops grown in that particular
climate or section.

'

Jfc.

FIG. 29. — Poor soil, poor crop.

This soil is not fertile because it does not produce a
good crop.

Crops Indicate Fertility. — Crop growth is the only indicator of
eoil fertility, and the use of good seed is the only proper means in
testing fertility. Since the requirements and adaptability of
different crops vary, a soil may be fertile for one or several kinds
of crops and not for another (Figs. 30 and 31) ; for example, a soil
may grow excellent crops of clover, potatoes (Fig. 32), corn,
and grains, but fail absolutely to grow alfalfa, for lack of
proper inoculation.

Factors Determining Fertility. — The factors which determine
soil fertility are discussed in the first pages of this chapter. They
may be thus enumerated as positive and negative factors:

FACTORS DETERMINING FERTILITY

81

FIG. 30. — A fertile soil This soil possesses all the qualities, properties and conditions
which impart to it productive power.

FIG. 31. — Harvesting hemp in Wisconsin. Crop growth is the indicator of soil fertility
This particular soil is in a high state of fertility.

Positive factors: (1) A suitable moisture supply in the soil.
(2) Sufficient air in the soil. (3) Good tilth (Chapter V). (4)
6

82

CROP PRODUCTION AND SOIL FERTILITY

Presence of helpful soil organisms. (5) Sufficient available plant-
food elements, nitrogen, phosphorus, potassium, calcium (carbon-
ate of lime).

A negative factor: (1) The absence of harmful agents in the soil.

FIG. 32. — Having power for maximum production. Yield 550 bushels to the acre —
following clover. A complete fertilizer was used at the rate of 2000 pounds per
acre. (Maine.)

Soil Fertility Illustrated.— Fig. 33 will help the student to
gain a clearer idea concerning fertility.

Let the tank represent a soil.

The capacity of the tank for holding water represents fertility,
or the power of the soil for producing a good or high yield.

The staves which determine the water-holding capacity of the
tank represent the positive factors which determine soil fertility.

The tank being free from any leaks represents the negative
factor, viz., the absence of harmful agents.

UNFAVORABLE FACTORS

83

If all the staves were as high as the concrete sides of the tank,
the tank would then hold its greatest amount of water. If all the
fertility factors were most favorable, the soil would have power
for producing maximum yields.

Just as the water-holding capacity of the tank may be limited
by the shortest stave, so fertility or the productive power of a
soil may be limited or brought to naught by one deficient element
or an unfavorable soil condition. Thus it is possible for a soil to

FIQ. 33. — Soil fertility illustrated. Just as the water-holding capacity of the tank may
be limited by the shortest stave, so fertility or the productive power of a soil may be limited
or brought to naught by one deficient element or an unfavorable condition.

lose its fertility or productive power through the depletion or loss
of a single fertilizing element.

Unfavorable Factors. — Many soils are unproductive because
one or more factors are unfavorable. In case of drained peat, the
common cause of poor crops, or failures, is the lack of potassium.
This condition can be corrected through the use of potash fertil-
izers— or in terms in harmony with Fig. 33, the shortest staves
may be lengthened by applying fertilizers carrying potassium.

In many instances, poor yields and failures in growing alfalfa,

84

CROP PRODUCTION AND SOIL FERTILITY

soy beans, beans, peas and other legumes may be due to no other
cause than the lack of proper nodule-forming organisms. In
hundreds of cases soils fertile for corn, potatoes, and grains, fail
to grow alfalfa because of both & lack of calcium (carbonate of
lime) and alfalfa nodule-forming organisms.

On many long-cropped prairie soils deficient available phos-
phorus is a common cause of low fertility and poor crops.

Soil Exhaustion. — Some soils which were at one time productive
are now regarded as exhausted, depleted or "worn out/' because

FIG. 34. — Depleted lands (in background), typical of the Appalachian and Blue Ridge
. es. Wooded hillsides are cleared of timber, cultivated, and through erosion and exhaus-
tive cropping are rendered useless, and allowed to revert to timber. In foreground, new land
recently cleared is in tobacco. (Kentucky.)

they no longer respond to cultivation as they formerly did (Fig. 34) .
An exhausted or depleted soil implies that something has been
used up or taken out of it. That " something" is commonly
understood to mean the fertilizing elements; viz., nitrogen, phos-
phorus and potassium. In some instances soil exhaustion may be
attributed largely to the removal, mainly through cropping and
leaching, of some one or all of the three named elements; not the
removal of the " total" amount, for this is impossible, but the
removal of the ' ' available " supply. If no phosphorus, for example,
were lost through leaching, it would require only about sixty years

SOIL EXHAUSTION

85

of exhaustive cropping to reduce the total phosphorus supply of
a fertile silt loam one-half.

The effect of exhaustive cropping on the phosphorus supply
is well illustrated in the following study of two pairs of soils which
represent two different silt loams. In each case the " virgin" and
the "cropped" samples are the same soil; the one has never been
under cultivation and the other has been subjected to exhaustive
cropping for over fifty years.

Effect of Exhaustive Cropping on the Phosphorus Content of Soils

Soil

Phosphorus content

Virgin soil

Cropped soil

Per cent

Pounds in 1 acre
7 inches deep

Per cent

Pounds in 1 acre
7 inches deep

I
II

0.12

0.074

2400
1480

0.06
0.04

1200
800

The following is a brief outline of the history of these two soils :

I. "Cropped sixty years, largely to wheat during the first ten
or twelve years; then corn and oats; clover ten years. The land
is now in a depleted condition."

II. "Cropped sixty-three years. During the first thirty-four
years wheat was grown almost continuously. Since 1878 it has
been rotated to corn, barley, oats and rye. It has never been
seeded down or manured and is in a badly exhausted condition."

Soil Exhaustion Not Confined to Just One Element orCondition.
— Generally an exhausted or depleted soil is the result of several
unfavorable conditions, which, acting together, bring about a
state of infertility. All the fertility factors are necessarily affected;
and instead of their acting favorably for good yields, they act
unfavorably and thus cause poor crops or prevent any yields at all.
The fertility factors are unfavorably affected largely by the
removal of organic matter, by the removal of available nitrogen,
phosphorus and potassium, by the removal of available calcium
in the form of carbonate of lime, and by poor tillage. It is not
always easy, therefore, to restore the original fertility of a badly
depleted soil. In many instances it has proved a tedious and
expensive undertaking.

86

CROP PRODUCTION AND SOIL FERTILITY

Diagnosing Infertility. — Knowing the meaning of fertility and
the factors determining it, any one can diagnose a case of infer-
tility or low productive power with a fair degree of accuracy, or
gain an idea, at least, as to the cause of failure or low yields. A
knowledge of the cropping history and past management of the
soil in many instances will greatly aid in arriving at any definite

FIG. 35. — This crop yielded 75 bushels of corn per acre. Rows were four feet apart
and hills in the rows three feet apart — one stalk in each hill. The secret — each stalk pro-
duced a little less than IK pounds of ear corn. (Mississippi.)

conclusion. For example, alfalfa failure on some soils may
be due to no other cause than the absence of alfalfa nodule-
forming organisms.

The Secret in Growing Good Crops. — The secret of a good
yield of corn consists in causing each stalk in the field to produce
at least one good ear (Fig. 35) . To attain this object a good farmer,
because of experience, selects a workable and desirable soil, pre-
pares a good seed bed, increases the richness of the soil by adding
manure or commercial fertilizers, cultivates the growing crop as
well as he knows how, and trusts to the weather for the rest
(Fig. 36).

MOST SOILS CAN BE IMPROVED

87

When we analyze this method of procedure, we find that the
farmer unconsciously brings into play the factors which determine
fertility; in other words, his whole program centers on soil fertility.
It is true in respect to growing a good yield of any crop. This
emphasizes the importance
of soil fertility and explains
why so much study is given
to it.

Most Soils Can be Im-
proved. — In the next six
chapters we shall study in
detail the several factors
which determine fertility in
their relation to soil im-
provement and to the
maintenance of fertility.
There are very few soils
that cannot be improved
in some way. To maintain
and increase soil fertility
should receive the serious
consideration of every
farmer, because fertile soil
is the basis of a successful
and prosperous agriculture.
It is, indeed, a patriotic
duty of every farmer to
maintain the fertility of his
soil, and to pass his land on to his children, or fellow farmers in
as good if not better condition than when it came into his hands.

FIG. 36. — Twenty-six potatoes from a single
hill, totaling 6K pounds — all from a piece of
potato having two strong " eyes." A good seed
bed, a good supply of available plant-food ele-
ments, thorough cultivation, a good moisture
supply, the absence of any disease, and protec-
tion from insect pests were factors which made
this yield possible.

Exercises With Seeds. — With the use of a hand lens examine specimens
of good and poor seeds. The samples should include fresh and old clover seeds,
chaffy and clean grass seeds, heavy and light grain, pure seeds compared with
others foul with weeds, etc.

Project Studies. — -Compare the growth of crops where poor lots of seeds
have been used in contrast with the best seeds. These may be on small plots.

2. Grow several lots of seed that have been selected for disease resistance.
Test their efficiency by contrasting them with others grown in similar surround-
ings. These may include cabbage which resists yellows, tobacco and tomato
which resist wilts, or others.

3. Sweet potatoes which have been selected from plants which are immune
to black rot disease should be grown as a home project. From the crop select
those which are perfectly immune and that are the best in yield, etc.

88 CROP PRODUCTION AND SOIL FERTILITY

4. Project in seed improvement for various farm and garden crops may be
conducted at homes of students.

Field Studies. — 1. Compare growth where the tillage is thorough with the
same crops under poor tillage.

2. Find examples where weeds have been smothered by heavy seeding of
crops as grains, cowpeas, millet, buckwheat, etc.

3. Make field studies to attempt to diagnose the fertility or infertility of
field at home or on other farms. See the suggestions in this and other chapters.

QUESTIONS

1. Name the factors upon which successful crop production depends.

2. What is meant by a fertile soil?

3. What makes a fertile soil?

4. What is a good combination to have in order to raise good crops?

5. What is good seed?

6. What advantage is there in planting large seeds rather than small ones of

the same variety? In planting disease-resistant varieties? In planting
improved varieties?

7. How may weather conditions affect crop growth?

8. What relation has the weather to the farmer's activities?

9. Discuss the relation of light to crop production.

10. What are the best conditions under which to grow sugar beets?

11. What are "smothering crops"? Explain how clover and alfalfa may serve

in this capacity. What about weeds?

12. What precaution should be observed in sowing nurse crops?

13. How may a farmer protect his crops from injury?

14. What is the meaning of soil fertility?

15. Give meaning of "to maintain fertility." "To increase fertility."

16. When is a soil said to have lost its fertility? What is infertility?

17. Fertility of a soil in your locality has meaning only in relation to

what crops?

18. What indicates soil fertility?

19. Name the factors determining fertility.

20. When is it possible to obtain maximum yields?

21. How may a soil lose its fertility or be limited hi its productive power?

22. Explain why peats are frequently unproductive. Give remedy.

23. What are common causes for failure of legumes?

24. What is the meaning of "soil exhaustion"? What is a common cause of

soil depletion?

25. What is the effect of exhaustive cropping on the phosphorus supply of

soils? Illustrate.

26. Explain why it is not easy to restore the original fertility of a badly ex-

hausted soil.

27. Illustrate how the cause of infertility or low yields may be reasoned out.

28. What is the secret in growing a good crop of corn?

29. Suppose corn is planted in hills 3 feet 8 inches apart each way, 3 stalks

in the hill, and each stalk produces an ear weighing three-quarters of a
pound when cured. What would the yield be? What would you do to
grow such a crop?

30. For an outline summary of this chapter see table of contents.

CHAPTER VIII

SOIL WATER AND ITS RELATION TO SOIL FERTILITY

Water is a most important though variable factor affecting
soil fertility. Crop yields may be much reduced by a lack of water
or by too much of it. The life processes and special activities of
plants as well as of animals are at all times dependent on the
water supply.

Why Plants Require Water. — In relation to plants, water
serves a number of purposes, as —

a. A nutrient. It may without change become a part of the
plant cell, or it may contribute to the making of foods.

b. A carrier for plant-food elements and plant-food. The salts
of the soil which contain nitrogen and the mineral elements,
and the carbon dioxide of the air, which contains the carbon must
be brought to the leaf cells in soluble form before they can be
utilized in food manufacture; and when the foods are made, they
are translocated within the plant in soluble form by means of
water (p. 50).

c. To keep the cells turgid, or expanded, to prevent wilting.
When plants cannot get all the water they need they wilt, and when
they remain wilted they die.

d. A cooling agent. The evaporation of water from the leaves
prevents their getting too warm. It has been found that even
with evaporation the leaf temperature may be ten to fourteen
degrees higher than that of the surrounding air.

e. An aid in life processes. Water is necessary to permit of
certain physical and chemical changes (life processes) within
the plant.

Further Importance of Water. — Water is a great solvent in
soils, and without it the necessary chemical changes in soils cannot
take place; nor can the helpful soil organisms develop and do their
work without moisture.

Crops Require Much Water. — Crops require tremendous
amounts of water; for example, in a humid climate like that east
-of the Missouri River, about 152 barrels of water are required
to produce one bushel of corn (Fig. 37). This means that in the

90 SOIL WATER AND ITS RELATION TO SOIL FERTILITY

production of a seventy-five-bushel yield for each twenty-three-foot
square area, the area necessary to grow one bushel must furnish
to the corn growing on it at least 152 barrels of water during the
growing season, or an equivalent of about thirteen inches. All
this water passes up through the plants and evaporates from the
leaves. This current of water passing up through the plant and
evaporating from the leaves is called the " transpiration current."
Approximately 140 barrels of water are transpired by the oat

Fia. 37. — One hundred fifty-two barrels of water are required to produce one
bushel of corn. The corn uses this amount of water. Water is an important factor in crop
production.

plants for each bushel of oats produced. The same amount is
required per bushel of barley. In a similar manner about 3800
barrels are required to grow a ton of clover hay, and about 4200
barrels to produce a ton of alfalfa hay.

" Water Requirement " of Plants. — The expression "water
requirement" of a plant refers to its needs and means the amount
of water that passes up through it and evaporates for every pound
of dry matter produced. Plants differ in their water require-
ments, and, for the same plant, climate influences this require-
ment considerably. In this country scientists have found the
water requirement of some crops to be as shown in the following
table:

IMPORTANCE OF RAINFALL AT THE RIGHT TIME

Water Requirements of Some Crops

91

Crop

Pounds of water transpired per pound dry
matter produced

In a climate similar
to that east of the
Missouri river

In sections having
10 to 20 inches of
rainfall, as in Colorado

Corn

271
385
464
504
576

368

636
534
597
789
831
584*

Potatoes

Barley ;

Oats

Clover (red)

Alfalfa

Common weeds

* Average of four weeds — purslane, pigweed, lamb's quarter and ragweed.

Soil Gives up More Water Than That Transpired.— The figures
in the table indicate only the amount of water that passes through
the plant. In addition to this there is about one-fifth this amount
of water lost by evaporation from the soil under conditions of
good soil management.1

Factors Influencing Water Requirement of Plants. — The
factors which influence the water requirement of crops are:

(a) The weather. If the air is hot and dry much more water
is required than when the air is cool and moist. Wind and much
sunshine also increase the amount of water transpired (last
column in table).

(b) The water supply in the soil. When the soil contains a
large supply of available water, plants are more lavish with it
than when there is a low supply or when the soil gives up its
moisture more slowly, as in a clay loam or silt loam.

(c) Richness of the soil. When other conditions are the same,
a plant requires about one-half the amount of water when grown
on a rich soil than when grown on a poor one.

(d) Manure and fertilizer treatments. The use of manure or
commercial fertilizers on poor soils not only increases the yield
but may decrease the water requirement of plants from thirty to
fifty per cent.

Importance of Rainfall at the Right Time. — If the rainfall came
at the right time and were evenly distributed in sufficient amounts,
wonderful results would be obtained. The size of the hay crop
.is largely determined by the character and amount of the rainfall

1 King's Soil Management.

92 SOIL WATER AND ITS RELATION TO SOIL FERTILITY

during the earlier stages of growth. .The oat yield is less dependent
on the character of the rainfall than is the hay crop. An ideal oat
year is fairly dry and warm during the time of sowing. During the
growing season, however, oats should have from three and one-half
to four inches of rainfall per month — about two inches every fifteen
days. If the rainfall should be less than this the grain would not
fill properly; if more, the oats generally grow too rank and lodge
easily, especially on manured lands. Temperature also affects
the yield. If the temperature should average rather warm while
the oat crop is just heading out, the yield may be reduced from
three to ten bushels per acre even though the moisture conditions
be favorable.

The yield of winter wheat is determined largely by the rainfall
during September and October, and by the snowfall and tempera-
ture during the winter.

Water the Limiting Factor in Dry-farming. — In dry climates
the water requirement of plants is greater than in a humid climate;
and, since the rainfall is so much less, water is the all important
problem and the limiting factor of production in dry-land farming.
Dry-land farming means the profitable production of useful crops
without irrigation in districts receiving an annual rainfall of from
ten to twenty inches. Every effort is made, therefore, in these dis-
tricts to conserve the rainfall for use by crops.

Moisture Often a Limiting Factor in Humid Climates. — In a
climate having an annual rainfall of more than thirty inches it
would seem that moisture can never be a factor limiting soil fer-
tility. The fact is, few seasons pass in which some important crop
is not reduced from one-fourth to two-thirds in yield because of
the lack of sufficient moisture, owing to the character and distribu-
tion of the rainfall. Sometimes the rain comes in torrential showers,
and much of the water is lost as surface run-off; sometimes the
snow melts rapidly while the ground is still frozen, and again much
water runs away; at times the rain comes in light showers and is
soon lost from the soil by evaporation; and frequently rains come
at the wrong time or do not come at all when most needed.

Water Problem in Semi-arid vs. Humid Climates. — The real
problem that confronts the dry-land farmer is, "Is it possible to
conserve and use the rainfall so as to make it available for the
production of profitable crops?"

In humid climates, because of water losses and irregularities in
rainfall which materially affect crop yields, the question arises,

HOW SOILS HOLD CAPILLARY WATER 93

"How and to what extent can farmers conserve the rainfall and
control the moisture in the soil to prevent any reduction in yield
because of short dry periods or to lessen the damaging effects
of drought?"

Before taking up the study of moisture conservation and con-
trol, it is necessary to consider first the forms of soil water, how
water is retained by soils for crop use, the movements of water in
the soil, and the capacity of soils for holding water for crops.

SOIL WATER

Forms of Soil Water. — Water in relation to soils may occur in

je forms or conditions; as —

(a) Gravitational or free water. Water which, if opportunity

given it, will flow off or run down through the soil and away

tuse of gravity.

(6) Capillary water. Water which is held by the soil against

ivity after all free water is allowed to drain out, but which is
to move from soil particle to soil particle.

(c) Hygroscopic water. Moisture which exists in air-dried soil,
or in soil in which plants permanently wilt. Usually a small amount
of capillary water is also present in soils when plants wilt.

Capillary Water Most Important. — Free or gravitational water
in wet lands should receive first consideration, since that is the water
which should be gotten rid of before such lands can be brought
under cultivation. In all soils having good drainage, however,
capillary water is the most important, because this is the form which
constitutes the soil moisture reserve from which crops draw their
water requirements. Free water is detrimental to most culti-
vated crops. Rice and cranberries are crops which are peculiarly
adapted to wet or saturated soils.

How Soils Hold Capillary Water. — Capillary water may be
held in soils in three ways, viz. :

(a) In form of films around the soil grains.

(b) In organic matter as in a sponge.

(c) In some of the pore spaces within soil crumbs or granules
(Fig. 6A).

A mineral soil can hold its greatest amount of capillary water
when moisture can be retained in all the three ways mentioned.

A clean sand can hold capillary water only as films around the
sand grains. A coarse sand is capable of retaining a compara-
tively small percentage of capillary water because of the less amount

94 SOIL WATER AND ITS RELATION TO SOIL FERTILITY

of surface per unit volume to which water films can cling. A fine
sand, on the other hand, can hold a larger percentage of capillary
water because there is a much larger amount of surface over which
water films can form.

A black silt loam or clay loam containing much organic matter
and being crummy in structure can hold a large amount of capil-

<£W'

^u-. -^m^

m

mm

wm?y .

FIG. 38. — Checks and cracks aid entrance of water into the soil, and facilitate perco-
lation of water through it. Silt loams, clay loams and clays check and crack when they
dry out.

lary water, for three reasons: (1) its fine texture affords much
surface for water films; (2) the organic matter has a high- water
absorptive capacity, and (3) the crumbs contain pore spaces,
many of which may become filled with water.

Peat holds the greatest amount of water per unit weight.

Movements of Water in Soil. — There are three important move-
ments of soil water — percolation, seepage and capillary rise of water.

Percolation is the passing of free or gravitational water straight
down through the soil (Fig. 38). This movement takes place
through the pore spaces in between the soil particles or crumbs.

SEEPAGE

95

This movement is fast in a coarse sand and very slow in a clay
loam of compact structure and in a clay.

Percolation Prevents or Lessens Soil Erosion. — If water can
penetrate and percolate through a soil easily, soil erosion is pre-
vented. A stubble field of heavy silt loam or clay loam on a hill-
side washes badly during a heavy rain because the water cannot
readily soak into and percolate through it, and because the silt and
clay particles are easily carried away by running water. If such
a field were plowed so as to permit the water to enter the soil,
erosion may be checked or much lessened.

Drainage Depends on Percolation. — When the ground is very
muddy the pore spaces in the soil are filled with water; in other
words, the soil is saturated or nearly so. If it were not possible

i

FIG. 39. — Diagram showing difference between percolation and seepage; A, the tilled
Boil; B, permeable subsoil through which free water percolates; C, sandy gravel substratum
through which ground water moves laterally; W, area at foot of slope kept wet by seepage
of water out from the upland; O, place to put tile to catch the seepage water.

for this surplus water to pass down and away, workable soils
would soon become unfit for cultivation. It is through percolation
largely that soils rid themselves of any free or gravitational water
whenever opportunity be given it to flow away.

Percolation Aided by Roots and Worms. — Many upland soils
are given better drainage through the penetration of roots into the
deep subsoil, and through the action of earthworms. When roots
of trees and of plants like alfalfa die there remain the openings
made by them. These openings, together with those made by
earthworms, facilitate percolation. Checks and cracks in the soil
also favor this movement of soil water.

Seepage is generally understood to mean slow lateral movement
of free soil water (Fig. 39). It is common in some localities to
observe water seeping out of hillsides. Soils occurring on the
borders of marshes are often much wetter than the interior of the
marsh, owing to the seepage of free or gravitational water out
from the upland.

96 SOIL WATER 'AND ITS RELATION TO SOIL FERTILITY

Capillary Rise of Water in Soils. — This is the upward move-
ment of water from the subsoil to the surface. This movement of
soil moisture concerns capillary water only. A good illustration
of this is the upward movement of water or oil in a lampwick.
Suffice it to say that the force which causes this rise of water either
in the soil or a lampwick is " capillarity."

When capillary water rises in soils it does not fill the pore
spaces in between the soil particles, but rises or moves from soil
grain to soil grain in films which surround the soil particles; thus
capillary water may move not only upward, but
in all directions, from a greater to a less amount
of soil moisture. It is important that the pore
spaces do not all become filled with water,
because it is through these openings that air
enters a soil; and air is one of the factors
determining fertility.

Factors Influencing Capillary Rise of Water.
— There are several factors influencing the rise
of water in soils, but we shall consider here only
those which are of practical importance to the
farmer; viz., soil texture, compactness or firm-
ness of soil, and obstruction.

Influence of Soil Texture. — Soil texture has
a decided influence on the rise of soil moisture.
In a fine textured soil water rises much higher
showing 4how~ SpiliaS but more slowly than in one of coarse texture
water rises in soils— in (Figs. 40 and 41). Capillary water cannot rise

films from soil particle v

to sou particle, s, soil uptnroughgravel or coarse sand; thus a seed bed
having a coarse sand subsoil is supplied with no
appreciable amount of moisture from the subsoil through capil-
larity. A seed bed of silt loam underlaid by silty clay, on the
other hand, may be supplied with considerable capillary water
from the subsoil to a depth of from four to five feet during a drought.
King concluded that moisture may rise in silt loam soils from depths
of ten feet in forty-five weeks. Another investigator has shown
water to rise in a very heavy soil to a height of only forty-six
inches in twenty-eight weeks. Since in a humid climate a drought
seldom extends over a period of six weeks, a seed bed of silt loam
on silty clay subsoil would probably not secure any moisture
from depths greater than four or five feet. Since in most soils in
humid climates roots of farm crops extend to depths of three to

OBSTRUCTION

97

four feet, and since moisture can rise to heights of from at least
three to five feet in fine textured subsoils below the root zone, it is
reasonable to assume that a crop growing on a silt loam having a
deep silty clay subsoil draws its moisture supply from six to nine
feet of soil during a drought.

Compactness. — Compactness or firmness means good contact

FIG. 41. — Capillary rise of water in soils.

between the soil grains and crumbs within the seed bed. Since
capillary rise of water is possible because of the films which extend
from soil particle to soil particle, we can readily understand how
compactness or good contact between the soil grains facilitates
this movement of water.

Obstruction. — Under field conditions practically the only

obstruction that may at times interfere with the rise of soil water

is too much coarse material plowed under; it may be too much

coarse manure or litter, a rank growth of clover, or too much

7

98 SOIL WATER AND ITS RELATION TO SOIL FERTILITY

strawy rye. Rye is commonly plowed under to add organic
matter to soils. For best results it should be plowed under before
it develops stiff straw. In either case cavities are formed which
impede or prevent the capillary rise of water from the subsoil
to the seed bed. This is especially true when sod is improperly
plowed just prior to a dry period. When much coarse litter is to be
turned under it is best to plow in the fall, and whenever it is done a
short time before planting good contact should be secured, if possible,
between the soil and subsoil by working the land and rolling it.

The Soil a Reservoir. — In the preceding chapter it was learned
that soils act as reservoirs in storing a portion of the water supplied
to them and giving it up again to growing crops. Soils vary in
this capacity because of differences in texture, content of organic
matter and structure. Thus it is that we speak of "water-holding
capacity" of soils.

Water-holding Capacity of Soils. — Water-holding capacity of a
soil is generally understood to mean the greatest amount of water
it can retain when all free water is given a chance to drain out.
The water thus held includes capillary and hygroscopic moisture,
and is expressed in per cent of the dry weight of the soil; for
example, if fifty pounds of a perfectly dry soil can hold fifteen
pounds of water after allowing all free or gravitational water to
drain out, that soil has a water-holding capacity of thirty per cent,
the greater portion of it being capillary water.

The following table shows how different soils vary in the amount
of water they can hold against gravity:

Water-holding Capacity of Soils

The approx-

Soils

Water-holding
capacity
(capillary and
hygroscopic

The equivalent
in terms of
inches of
water in one

imate amount
that crops can
use from one
acre one foot

water)
per cent

acre one foot
deep*

(Available or
capillary

water)

A coarse sand

15

3.2 inches

3.0 inches

A fine sand

22

4.2 inches

3.6 inches

A light colored silt loam

30

4.4 inches

2.6 inches

A black silt loam

45

6.0 inches

4.0 inches

A well-decomposed peat

134

10.2 inches

6.8 inches

* Obtained by multiplying the weight of soil by the per cent water-holding capacity,
and reducing result to inches.

t Roots cannot absorb the last trace of capillary water held in soils, because when the
water films become very thin the attraction between the soil grains and the thin films becomes
as great or greater than the absorptive power of the roots. The finer the soil the more
hygroscopic or unavailable moisture held. Crops may wilt and cease to grow in silt loams
and clays when still carrying 12 and 14 per cent moisture, respectively, while they may
grow well in coarse sand possessing but 1 to 3 per cent water.

SOME SOILS ARE DROUGHTY

99

Moisture Supply Better in Silt Loams Than in Sand. — Sandy
soils give up their water much more easily and completely than silt
loams and clays, nevertheless the latter soils generally furnish to
crops a much better moisture supply.

The figures in the last column of the table seem to indicate
that crops would suffer less for want of water on a coarse sand
than on a light colored silt loam during a drought. On the con-
trary, crops suffer much more on the sand, for two main reasons:

FIG. 42.— A droughty soil. A fine loam about 14 inches deep underlaid by coarse sand

and gravel.

(1) Sand gives up its water more easily than silt loam and
hence plants are more lavish with it.

(2) In the coarse sand, roots cannot secure moisture by capil-
larity from depths below the root zone.

Thus it is that corn on sand grows faster than on a silt loam
and shows no injury because of lack of rain during the beginning
of a dry period, but suffers much for want of water later on as
the dry weather continues.

Some Soils are Droughty. — Soils which are unable to furnish
crops with sufficient moisture during short dry periods are called
"droughty" — a deep coarse sand is a good example (Fig. 42).
Often the best appearing loam or silt loam proves droughty, because
it is underlaid at a shallow depth by a coarse and porous subsoil,

100 SOIL WATER AND ITS RELATION TO SOIL FERTILITY

such as coarse sand or gravel. During a dry period the main source
of moisture that crops can draw on is the capillary water stored
in the shallow surface stratum, since no water is supplied to the
seed bed by capillarity from lower depths. Furthermore, roots
extending into a gravelly subsoil can secure but little moisture.
In contrast to this, a silty clay subsoil, for example, furnishes much
water to the seed bed, and to the deep roots extending down into it.
Moreover, a seed bed underlaid by a fine textured subsoil can hold
more capillary water than if the subsoil were sand or gravel.
In buying a farm it is important to examine into the nature of
the subsoil to ascertain whether or not it can furnish the seed bed
with any capillary water and supply the deep roots with sufficient
moisture; and whether or not it can permit percolation sufficient
at least to favor proper drainage.

MOISTURE CONSERVATION AND CONTROL, WITH SPECIAL REFERENCE
TO HUMID FARMING

The loss of water from rainfall may occur by running off the
surface of the soil, by percolating through it, and by evaporating
from it. Roughly speaking, only about twenty-five to thirty per
cent of the rainfall in a humid climate is used by crops — the rest
is lost (Fig. 43). Moisture conservation and control consists
(a) in preventing surface run-off as much as possible; (6) in increas-
ing water-holding capacity of soils; (c) in aiding capillary rise of
soil moisture; (d) in lessening the loss by evaporation either from
the soil or through weeds; (e) in draining wet lands, and (/) in
supplying water through irrigation.

How Run-off May be Lessened. — Loss of rainfall through
surface run-off may be much lessened by aiding soils to catch or
trap water. This may be accomplished in several ways: (a) by
fall plowing; (6) deep hillside plowing; (c) by loosening up any
hard and compact soil and subsoil; (d) by plowing at right angles
to the slope or hillside, and (e) by terracing. Any one of these
methods permits more of the rainfall to soak into the ground, and
that which is not stored or retained by the soil passes on down and
away. In some sections, and especially on hillsides, the storage
of water by the soil during late fall, winter and early spring, or at
any other time, is greatly hindered, because no provision is made
whereby soils can catch the rainfall. Any other method whereby
soils may be aided in "trapping" and storing water from rainfall
is worthy of consideration.

MOISTURE CONSEK.VATION

101

a-OOOOOOOW- T

OK°-------° C

§i i f |f 1 1|| I a

102 SOIL W'ATER AND. JJS RELATION TO SOIL FERTILITY

How Water-holding Capacity May Be Increased. — Since the
amount of water retained against gravity by most soils is deter-
mined largely by texture, organic matter and structure, it is plainly
seen that the water-holding capacity of a sand, for example, cannot
be increased by improving its texture. Texture of a sand, or of
any soil, remains practically the same, and the structure of a sand
cannot be materially changed in a short time. Thus the only
course open, in case of sand, is to increase the organic matter.

In case of a "heavier" soil, water-holding capacity may be
improved by increasing the organic matter and by loosening it if
it is very compact. The addition of organic matter also tends to
develop a crummy structure which is favorable to water-holding.

Organic matter may be increased by plowing under clover or
green rye, by plowing under a good sod as often as possible, through
the application of farm manure and through the application of
peat, if convenient.

Aiding Capillary Rise of Water. — Good contact between the
soil particles favors capillary rise of water. This is an important
reason why a firm seed-bed is generally desirable. Not only should
the seed bed be firm, but there should also be good contact between
the seed bed and the subsoil — in this respect fall plowing is advan-
tageous, also working the land and rolling it.

A seed bed too loose and lacking good contact with the subsoil
is not a favorable environment in which to plant seeds, especially
if they be small like clover and alfalfa. If frequent rains do not
occur when such conditions exist, germination is poor and the
crops may be failures.

Special attention should be given to compacting the seed bed
when deep plowing is done just before seeding or planting — par-
ticularly when the soil is sandy or loamy.

Subsoiling heavy soils to enable them to trap and store more
water is to be recommended in some instances, but subsoiling land
having sand or sandy subsoil is to be discouraged, since it is desir-
able to maintain compactness of a sand subsoil to favor capillary
rise of soil moisture, to retard loss of water through percolation,
and to lessen excessive leaching.

Lessening Evaporation of Soil Moisture. — Under field condi-
tions losses through evaporation may be decreased more or less
by developing a top layer of loose, dry soil. Such a protective
layer is called a "soil mulch" (Fig. 44). A soil mulch may be
developed and maintained throughout the growing period only in

HOW A SOIL MULCH CONSERVES MOISTURE

103

fields planted to crops like corn, potatoes, cotton, or any other
crop planted in rows so as to permit of intertillage.

What Constitutes a Good Soil Mulch. — On silt loams, clay
loams and clays a good mulch consists of a layer of loosened and
dry soil composed either of crumbs or a mixture of crumbs and
small lumps. A dust mulch is undesirable because it becomes a
hard crust when a hot sun shines upon it after a rain, whereas a
crummy layer does not crust and bake so easily.

A good mulch on sandy soils consists of a loosened and dry layer
of sand

FIG. 44. — How a soil mulch conserves moisture. The footprints are kept moist because
the soil moisture is permitted to move to the surface and evaporate. After awhile the foot-
prints will become hard and dry, while the soil beneath the mulch will be mellow and moist.

In a humid climate it is not generally necessary to make a soil
mulch deeper than three inches. Many are very effective when only
an inch or two in depth, especially in gardens and on heavy soils.

How a Soil Mulch Conserves Moisture. — The protective action
of a soil mulch in lessening the loss of moisture is based on three
principles: (1) The looseness of the soil hinders the movement
of capillary water from soil particle to soil particle. (2) The dry
surfaces of the soil particles and crumbs offer resistance to the up-
ward movement of water films. (3) A surface layer of dry soil
keeps the soil below it somewhat cooler, thus lessening the ten-
dency of the soil moisture to evaporate. When the surface layer
of a soil is loosened, therefore, the capillary rise of moisture is

104 SOIL WATER AND ITS RELATION TO SOIL FERTILITY

immediately checked, hence the loosened layer soon dries out.
When dry, each soil particle and crumb aids in lessening the escape
of moisture from below by offering resistance to the rise of the
water films (Figs. 40 and 44).

Cultivation Is Necessary to Maintain Mulch. — In order to
maintain both a loosened and dry condition of a soil mulch it is
necessary to rework the ground even though no rain falls, because
the loosened layer, owing to its own weight, gradually reestablishes
a greater or less degree of compactness which in turn favors
capillary rise of film moisture. Rain generally destroys the effec-
tiveness of a soil mulch; so that if the mulch is further desired, it
should be reestablished through cultivation (Fig. 44).

Mulch of Greatest Value During Dry Periods. — A soil mulch
is of the greatest value during dry periods. When frequent rains
keep the soil well supplied with moisture the main object of
cultivation during such periods is to kill weeds and to aerate the
soil, and not so much to establish a mulch to conserve moisture.

Aside from the fact that a mulch conserves moisture, it is
important to mention here that heavy soils are much easier to work
during dry periods especially, when a mulch is maintained.

Self-forming Mulches and Protective Crusts. — Very rapid
evaporation causes the surface few inches of a sandy soil, peat or
muck to become quickly dried out even though no cultivation be
given it, and because of this rapid drying out, the films of soil
water become broken, so that the dried surface zone acts as a
mulch. This explains why some uncultivated soils lose more
water through evaporation in a humid than in a semi-arid climate.

On certain loams and silt loams of crummy structure, self-
formed crusts, which break away from the soil beneath, become
effective in lessening water losses. These detached crust-like
layers vary from a fourth to about two inches in thickness, and
are formed as a result of rapid evaporation. Crusts not so loosened
from the soil beneath would increase evaporation.

Mulches of Other Kinds. — Straw, manure, leaves, grass and
other materials are used to a more limited extent for mulching;
in many instances to conserve moisture, to keep down weeds, for
fertilizing, to avoid soil washing, and in other cases to prevent
injury from repeated freezing and thawing during winter and
early spring.

Weeds Are Moisture Robbers. — The water requirement of
weeds is greater than that of corn; thus a growth of weeds in a

SOIL MULCH IN CONSERVING MOISTURE 105

crop represents an enormous loss of moisture which should go to
the crop (see first table in this chapter). The killing of weeds,
therefore, is an important factor in moisture conservation.

Demonstrations. — Material Needed. — One balance; a baking-powder can;
a piece of cheese cloth; 6 student lamp chimneys, or j^-inch glass tubes 12 to
16 inches long; a few pieces of lump sugar (cubes); a few teaspoonfuls of
powdered sugar; red ink; a saucer; a few fine needles; some road dust; a piece
of dusty board; 2 one-gallon crocks; about a quart each of air-dried loam,
fine gravel, coarse sand, fine sand, silt loam; and 8 quarts of loam or silt loam.

To Make Clear the Meaning of the Three Forms of Soil Water. —
Procedure. — A. Allow the plants in the crock that was kept in the greenhouse
(Demonstration No. 4, Chapter V) to dry up and die. Now take out of the
crock 100 grams, or about 4 ounces of soil, and dry it at 105° C. or 221° F.
(to prevent burning of organic matter) for 3 to 5 hours. Weigh again and deter-
mine the per cent of water contained in the air-dried soil. Most of this water
is hygroscopic water.

Plants are wilted and dying in a sand and a clay loam. Which soil contains
the more hygroscopic water?

B. Over the perforated bottom of a baking-powder can, or over the open-
ing in a funnel, place a piece of cheese cloth. Fill the can or funnel nearly
full of air-dried loam. Pour on the soil a measured amount of water and
allow to drain.

Questions. — (a) Did all the water drain through the soil?

(6) What is the water called that drained through?

(c) Name the water that was retained by the soil.

To Observe the Rise of Capillary Water in Soils and to Study Some of
the Factors Which Influence This Process. — Procedure. — Tie some cloth over
the lower end of student lamp chimneys, or %-inch glass tubes (Fig. 41).
(Tubes should be at least 12 to 18 inches long.) Fill student lamp chimneys
or tubes with dry soil as follows:

No. 1. — Fill with dry gravel; tamp well.

No. 2. — Fill with dry coarse sand; tamp well.

No. 3. — Fill with dry fine sand; tamp well.

No. 4. — Fill with dry silt loam; tamp well.

No. 5. — Fill as in No. 3 to within one inch of the top; tamp well. Fill to
top with dry, crummy silt loam — do not tamp. (This top layer of loose, dry
crummy soil serves as a soil mulch.)

No. 6. — Fill as in No. 3 to within 6 inches of the top; tamp well. Now
place on top of this soil column half an inch of cut up straw, dry grass, or hay;
then fill to top with dry fine sand — tamp well (see Fig. 40).

Place soil columns in a pan in a vertical position, then pour about half
an inch of water into the pan. Observe results at end of 5 minutes; after
1, 2, 3, 4 and 5 days, respectively.

Questions. — (a) Why is it necessary to have good contact between the
soil particles within the seed bed. Between the soil and subsoil?

(6) What is a droughty soil?

(c) What effect has texture on the capillary rise of water in soils?

To Demonstrate the Principle of Soil Mulch in Conserving Moisture. —
Procedure. — A. Observe results in tube No. 5, previous experiment.

B. Sprinkle as much powdered sugar on top of a lump (do not press down
the powdered sugar) as it will hold, and place the lump in a pool of about 12
drops of red ink poured out on a white dish. Observe results.

The lump of sugar represents soil, and the powdered sugar a soil mulch.

C. Fill a saucer with water; place a perfectly dry, fine needle carefully
on the surface film of the water. The needle will float. Why? Take a pinch

106 SOIL WATER AND ITS RELATION TO SOIL FERTILITY

of dust and let drop carefully into the water. What happens to the finest,
dry particles? Explain. Why do drops of water roll off a dusty board like
so many shot?

To Note the Effect of a Soil Mulch on the Rate of Evaporation from a
Silt Loam or Loam. — Procedure. — Fill one gallon crock level full of air-dry silt
loam or loam. (In filling establish good contact between the soil particles.)
Determine weight of soil in the filled jar. Moisten with water until a good
supply of capillary water is held throughout the soil. Weigh again and deter-
mine the per cent of capillary water contained in the soil.

Fill a second crock in a similar manner as No. 1, only fill within two inches
of the top. Water, and determine the per cent capillary water as in No. 1.
Now fill crock to level full with dry, crummy soil (soil mulch).

Place both crocks in a breezy place and determine the per cents of capillary
water in the two soils in the two crocks at the end of a week or ten days. Do
not water.

Have students record results.

Questions. — (a) What constitutes a good soil mulch? On sand? On
silt loam?

(6) When is a soil mulch most effective? (Consult text.)

Laboratory Exercises. — Mate-trials Needed. — Three large and 3 small baking
powder cans; some cheese cloth; one 20-mesh screen; one 40-mesh screen; one
pie tin; one soil auger; one balance; 4 quarts each of dry coarse sand, fine sand,
and a mixture of coarse and fine sand; one quart each of dry crummy silt loam,
peat, muck and pulverized peat.

To Determine the Porosity of Soils. — Procedure. — Punch a hole in the
bottom of a baking-powder can. Place a piece of cheese cloth over the bottom
on the inside, and fill the canfull of dry, coarse sand (screen out all fine material).

Now set the can into a dish of water so that the surface of the soil is about
on a level with the surface of the water on the outside. Allow the soil to
become saturated so that free water is noticed on the surface of the soil. Place
finger over the hole in the bottom of the can, take can out, and allow all free
water to drain into another can to be measured. The amount of water in cubic
inches represents the amount of pore space in the soil. Determine the per cent
of pore space in the coarse sand. (3!£ X square of radius of soil column X height
of soil column = cubic inches.) Record results as follows:

Soil

Number cu. in. soil used

Cu. in. water used to
saturate soil

Per cent pore space by
volume

Repeat the experiment by using a fine sand (screen out all coarse material),
and a mixture of coarse and fine sand.

Questions. — (a) What is the relation between the size of soil grains and
porosity of a soil?

(6) Would the pore space in clay be greater or less than in sand? Why?

(c) How does'porosity of a soil affect the rate at which water will percolate
through it?

(d) Will dry clay loam weigh more or less than fine sand? Why?

(e) What are the conditions producing the least amount of pore space in
a soil? (Note pore space in mixed sand.)

To Observe the Movement of Capillary Water in Soils.— -Procedure. — Pour
a cupful of dry sand or loam on a pie tin in a conical pile. Pour about a
third of a cupful of water into the tin (not on the pile of soil) and observe results.

QUESTIONS 107

Questions. — (a) What is meant by capillary movement of soil water?

(6) In what direction does capillary water move in soils? (Consult text.)

(c) What determines the direction of movement?

To Study the Power of Soils for Holding Capillary Water. — Procedure —
Fill ;i small baking-powder can having a perforated bottom, with air-dried,
coarse sand. Determine the weight of the soil by subtracting the weight of
the can from the weight of can plus the dry soil. Pour water on the soil until
thoroughly wet. Allow all free water to dram out, and determine the per cent
of capillary water retained. (Use weight of air-dried soil as basis.) Repeat
the experiment by using an air-dried, fine sand, a crummy silt loam, and a
peat or a muck. Record results in tabulated form.

Questions. — (a) Name the factors determining the water-holding power
of soils.

(6) Of what importance is the fact that soils can retain moisture? (Con-
sult text.)

To Determine the Effect of Organic Matter on the Water-holding Power
of Soils. — Procedure. — Take a baking-powder can one-half full of the same
air-dry, fine sand used in the previous exercise and mix with it an equal volume
of pulverized peat, or some other suitable organic matter. Determine the water-
holding power of this mixture. (Allow the organic matter to become well
soaked before draining off the water.) Compare results with those obtained
in the previous experiment.

Questions. — (a) What is the effect of organic matter on the per cent of
capillary water held?

(6) Does this mixture actually contain more capillary water than the fine
sand alone? Determine.

(c) How may the water-holding power of a sand be increased? Of a
silt loam?

To Determine to What Extent Weeds Use Soil Moisture. — Procedure. —
Secure a pint sample of soil (to depth of at least 8 inches with soil auger) from
an area in the garden or field where weeds are growing thick and thrifty.
Collect a similar sample from another portion of the same field or garden where
land has been well cultivated and weeds killed. (Do not collect these samples
soon after a rain, but rather near the close of a dry period.) Place these
samples in baking-powder cans to prevent drying out. Weigh, and dry at
temperature of 105° C. or 221° F. Determine the per cent of moisture in the
two samples. (Use weight of soil as collected in field for basis.)

Question. — (a) Name several reasons why weeds should be destroyed.
(Consult index.)

Field Studies. — Determine if possible why some soils dry out so easily.

Observe different conditions which aid soils to trap water.

Observe the effect of a good soil mulch and of any other kind of mulch.

QUESTIONS

1. What is the relation of moisture to soil fertility?

2. What use do plants make of water? What is the importance of moisture

in the soil itself?

3. What can you say concerning the amount of water used by crops?

4. What is meant by "water requirement" of a plant? How do crops differ

in this respect?

5. About how much water is lost by evaporating from the soil in growing

a crop?

6. What are the factors which influence the water requirement of crops?

7. Tell of the importance of rainfall at the right time during growth.

8. What is dry-land farming? What is the limiting factor of production in

this kind of farming?

108 SOIL WATER AND ITS RELATION TO SOIL FERTILITY

9. Is moisture ever a limiting factor in production in humid farming? Explain.

10. What is the problem that confronts the dry-land farmer? What is the

problem concerning the water supply in humid farming?

11. Name and define the three forms of soil water. Which is of most import-

ance in crop production?

12. How do soils hold capillary water? When can a soil hold its greatest

amount of capillary water?

13. Compare a coarse sand with a fine sand in the amount of water it can hold

for crop use.

14. Why can a black silt loam hold a large amount of capillary water?

15. What is percolation?

16. What is the relation between percolation and soil erosion?

17. What is the importance of percolation in land drainage? What facilitates

percolation under field conditions?

18. What is seepage? Illustrate.

19. What is meant by capillary rise of soil moisture? Give other illustrations

of this phenomenon. How does capillary water rise in soils?

20. Name and discuss three factors influencing capillary rise of soil water

which farmers should consider.

21. What is meant by water-holding capacity of a soil? How do soils vary

in this capacity?

22. What forms of soil moisture does "water-holding capacity" include? Can

plants use all the water indicated by* 'water-holding capacity"? Explain.

23. Compare the available moisture supply a light-colored silt loam can hold

with that of a coarse sand.

24. What are "drouthy" soils? What is an important point to consider with

respect to subsoil in buying a farm?

25. Mention ways in which water from rainfall may be lost to the crops.

26. Name ways in which moisture may be conserved and controlled.

27. How may surface run-off be lessened?

28. How may the water-holding capacity of soils be increased?

29. How can a farmer aid capillary rise of soil moisture? Why is it best not

to subsoil land having sand as subsoil?

30. What is a soil mulch? Under what conditions can it be maintained?

31. What constitutes a good soil mulch in humid farming? In dry-land

farming?

32. Explain by use of a diagram how a soil mulch conserves moisture. How

may a soil mulch be maintained?

33. When is a soil mulch of greatest value? How does a soil mulch aid

cultivation?

34. What are self -forming mulches and "protective crusts"?

35. Explain the uses of straw and other materials used as mulches.

36. What bearing have weeds on moisture conservation?

PROBLEMS

1. A barrel of water weighs 263 pounds and an acre of water one inch
deep weighs 113 tons. How many inches of water are required to grow a
50-bushel oat crop? A 2-ton clover crop? A 5-ton alfalfa crop?

2. If on a certain farm % of the rainfall during the growing period is
used by the crops, & is lost by percolation, % lost as surface run-off and %
the amount used by the crops is lost through evaporation from the soil, how
many inches of rainfall would be required to grow the crops in problem 1?

3. What per cent more water is used by the clover plant in a semi-arid
than in a humid climate? Assuming this would apply to alfalfa, about what
would be the water requirement of alfalfa in a humid climate?

CHAPTER IX

LAND DRAINAGE AND IRRIGATION

THIS chapter may be considered as a continuation of the sub-
ject of "Moisture Conservation and Control/' which was partly
considered in the preceding chapter.

Land drainage may be defined as getting rid of free or excess
water from wet lands. This subject is a broad one, touching
both the field of engineering and of soil management. Because
of lack of space, we shall study in this chapter the relation of good
drainage to soil fertility, and consider the fundamental principles
'of land drainage and irrigation.

Too Much Water is Harmful. — It is common knowledge that
water standing long on a cultivated field either injures or destroys
the crop. This injury is largely the result of the shutting out of the
air and the checking of the soil activities, because of too much water.

Other Harmful Effects of Too Much Water. — Wet soils are
cold, and this retards germination and plant growth. Too much
water makes fields, or portions of them, unfit for cultivation. Much
injury is done poorly drained soils when they are worked too wet.
Injury of crops by heaving (through frost action) is greater on
wet lands than on those having good drainage. Wet fields which
become dry enough to permit of late planting are less profitable
than when well drained; moreover, such conditions make crop
production uncertain (Fig. 45). It is generally recognized that
wet swamp lands are detrimental to public health.

Benefits of Proper Drainage. — Many direct benefits are to be
derived through proper drainage. The most important are
the following:

1. Soils Warm Up Better. — Water requires much heat to warm
it, and a very great amount to evaporate it.1 A little of the heat
of the sun is absorbed by the water in a wet soil, but the moat of
it is used up in evaporation. Thus it is that a wet soil is a cold
soil (Fig. 46). If the same land were well drained, the heat of
the sun would be absorbed by the soil instead.

1 To raise the temperature of a pound of water (1 pint) 1° F., requires
1 British heat unit. To evaporate a pound of water requires 966.6 heat
units. It requires no more heat to raise 7 pounds of dry loam one degree
than to warm a pound of water one degree.

109

110

LAND DRAINAGE AND IRRIGATION

The free movement of air, possible only in a well-drained soil,
aids materially in warming it.

The most effective soil-warming agent is warm rain water.
We all know how quickly the dormant vegetation starts growing
in early spring when a warm rain sinks into a well-drained soil.
Water-logged soils are not benefited in this way by warm rains,
because all the rain water is forced to run away as surface water.

FIG. 45. — A crop on a well-drained soil has a better moisture supply than when planted
on a wet soil. A, diagram showing root development in a wet soil; W, high water-table;
showing root development in the same soil but tile drained; T, tile; M, lowered

B, diagram
water-table.

(Page 95.-)

2. Roots Grow Deeper and Stronger. — Plants growing in soils
that are wet or water-soaked develop shallow root systems (Fig.
45). Marsh grasses and tamarack, for example, are shallow
rooted. Corn and other crops will not send their roots into a
water-soaked subsoil, but will develop them near the surface.
Drain a marsh, and the wild grasses and the tamarack die, because
the surface soil dries out, and the shallow roots are left without
water — capillary rise not being rapid enough to supply sufficient
moisture from lower depths. This helps to explain why corn
planted on land that is wet during the early growing period suffers
for want of water during the summer when the land becomes dry.
It seems strange, but it is true, that crops are able to get a better

MORE PLANT-FOOD ELEMENTS BECOME AVAILABLE 111

supply of moisture in a well-drained soil than in a wet one — all
on account of more and deeper roots.

Not only are plants able to secure more water when they
develop deep roots, but they are able, also, to secure more of the
plant-food elements.

3. Soil Organisms Develop Better. — Water-soaked soils are
practically devoid of helpful organisms, while those well drained
are usually abundantly supplied with them (Chapter VII).

FIG. 46. — Wet and cold subsoil injured the corn crop. For many years nobody sus-
pected that seepage water was the cause of poor corn crops on a large portion of this field
even though heavy applications of manure were made. To the left, good corn; to right,
injured corn. (See Fig. 39.)

4. Injurious Substances May be Removed. — Proper drainage
may be the means of getting rid of certain injurious substances in
soils. In some wet marshes, acids have accumulated to such an
extent that the soils have become extremely acid in character. When
such soils are drained, the accumulated acids are leached out,
sometimes almost completely, during the first three or four'years
after thorough drainage has been established.

The thorough drainage of alkali spots is the best treatment
recommended. Drainage is the method sometimes used to elimi-
nate injurious salts from alkali soils (Chapter IV).

5. More Plant-food Elements Become Available. — The
entrance of more air in the soil, a warmer soil, the development of

112 LAND DRAINAGE AND IRRIGATION

helpful soil organisms, and the growth of more and deeper roots
are results of proper drainage, which, in turn, become important
factors in making available the plant-food elements. Thus a
well-drained soil can perform its functions in relation to plant
growth much better than if it were too wet, or water-logged.

6. Good Drainage Favors Better Farm Management. — When
all the fields on a farm are well drained, the farm can be managed
more profitably — cultivation is made easier, square fields are made
possible, fields can be laid out to best advantage, seeds can be
planted better, crops can be planted earlier and hence are given
a longer growing period, fall frosts are delayed, bigger crops can
be produced, and farm work in general is not hampered unneces-
sarily because of wet fields.

Why Lands are Wet. — Some depressions on uplands are wet
because of lack of surface drainage, coupled with impervious
subsoils which prevent the water from soaking away. Some level
and fine textured uplands having "tight"2 subsoils are wet largely
because the surface water runs away very slowly. Seepage accounts
for many wet areas, both on uplands and lowlands. Many low-
lands and uplands are periodically wet because of flood water.
Some lowlands are wet because they are so nearly on the same level
with streams or bodies of water that the escape of free water
is impossible.

Much Land Needs Drainage. — There are in the United States
a total of about 122,000 sections (square miles) of land unfit for
cultivation because of too much moisture, but which could be
profitably drained. This is equal to the combined areas of Iowa,
Wisconsin, Massachusetts, Connecticut and Rhode Island.

How Drainage is Accomplished. — Wet lands can be made dry
in different ways, depending largely upon the nature or source of
the damaging water.

1. Surface Drainage. — Getting rid of surface water is called
surface drainage. When the offending water is that which stands
on the surface after rains, drainage may be effected by giving it
a chance to flow away through furrows or shallow ditches. If the
damaging water is that which flows from uplands to lower, 'and
across lower areas, during flood flow, drainage may be accom-
plished by controlling the course of the water through the use of
surface-runs and shallow ditches.

1 A "tight" soil or subsoil is one through which water cannot pass except
very slowly.

METHOD OF DRAINAGE 113

2. Subsurface Drainage. — When the damaging water is in the
soil, or when the water-table3 is too high, " subsurface" or "under-
drainage" is necessary. This may be done through the use of
open ditches and underground or covered drains.

3. Vertical Drainage. — Occasionally water standing in upland
depressions and on some flat upland fields may be given a chance
to escape by making openings through the tight sqil, or subsoil,
so that the water may move downward into an open and dry soil
below, if such a substratum is to be found.

4. Combined Methods Necessary .—It is generally necessary to
combine different methods of drainage. On nearly all large areas
the best combination for thorough drainage is large open ditches
for outlets, and underground drains. Under certain other con-
ditions a surface-run combined with underdrainage gives best

FIG. 47. — Dead furrows as drains. On tight soils, especially on fields having little
slope, surface drainage may be had by plowing in narrow " lands " up and down the gentle
slopes. The surface water drains from the back furrows to the dead furrows, thence down
the dead furrows and off the field. B, back furrow; D, dead furrow. (See Fig. 68.)

results. In many large areas effective drainage is accomplished
only through the combined use of open ditches, underdrains and
surface-runs (Figs. 48 and 50) .

Method of Drainage Depends Upon Why Land is Wet. — The
only reasonable and safe way to begin any efforts towards drainage
is to ascertain why the land is wet, and this knowledge should
determine the manner and system of drainage to be employed.
In most cases it is easy to determine when surface drainage is
needed; but underdrainage is too often overlooked. On many a
field the farmer never suspects a lack of sufficient drainage to be
the cause of low crop yields.

To eliminate any guessing in ascertaining the need of sub-
surface drainage, dig a post hole about four or five feet deep,
preferably during seeding time or when the ground seems too wet
and cold to work; and if, when the hole is left open, the water
comes within three feet of the surface, the land is in need of
underdrainage. Many grasses make good growth on land satu-

3 The surface of the free water, or ground water, in a soil, is called the
" ground water-table." When the free water comes near the surface, the ground
water-table is said to be high.
8

114

LAND DRAINAGE AND IRRIGATION

rated with water to within three feet or even eighteen inches of the
surface. Most farm crops, however, do best when such lands are
thoroughly drained.

Use of Spade May be All That is Necessary. — Frequently
water standing in a cropped field may be gotten rid of by spading
a shallow trench to some drain or roadside ditch. Sometimes
the placing of a galvanized steel culvert under a road-bed, or the
mere lowering of such a culvert, is all that is necessary to enable
the water to escape, or to prevent its backing up on the land.

FIG. 48. — A well-sodded surface-run. The grass prevents soil washing. (Wisconsin Station.)

Plow Furrows as Drains. — On tight soils, and where fields have
little slope, water from rainfall causes much injury because of
insufficient natural surface drainage. The plowing of these fields
in narrow strips of about four rods wide up and down the gentle
slopes often provides good surface drainage. When this method
is practiced, the "back furrows" should form slight elevations
running lengthwise through the middle of each plowed strip, and
the "dead furrows" should be kept open. In this manner the
water from rains or melting snow drains from the back furrows to
the dead furrows, thence down the dead furrows and off the
field (Fig. 47).

Surface-run a Necessary Drain. — A surface-run is a shallow
low runway for water — about one and one-half feet deep and ten

OPEN DITCHES

115

feet wide at the top (Fig. 48). It is used to remove surface water
during heavy rains and melting snows. Such a run may be con-
veniently used to protect depressions, and to prevent surface
water from entering a lower area. These drains should be kept
well sodded. As a rule a drainage system is not complete unless
surface-runs are provided to take care of the excess water during
flood flow.

Open Ditches. — Frequently small open ditches about 3 to 5
feet deep are employed, in place of surface-runs, to prevent flood
water from flowing on to low lands; the water is thus carried
around the low area or to one side instead.

=•' ,c I!" '" ''• '" =' if. 'iH *

•J.' - •- = r L W| =

FIG. 49. — A small open ditch properly located. This serves as a makeshift outlet for the
tile system until the bed of the stream is lowered by a dredge. (Wisconsin Station.)

A small open ditch about four feet deep and seven feet wide at
the top is sometimes dug through a low marsh kept wet by a slug-
gish stream, to serve as a temporary outlet for a system of tile
or underdrainage, until the stream is lowered and straightened by
a dredge (Fig. 49).

Open ditches of considerable width and depth are employed
in large marshes where much water is to be removed and where
the fall is slight. Such ditches are of primary importance because
they form the outlets. They are dug by means of dredges. In
many marshes having winding and sluggish streams these ditches
are made by straightening and deepening the water-courses.

On extensive marshes large open ditches, or canals, are con-
structed every mile or half-mile, with large tile at regular intervals
in between them.

116

LAND DRAINAGE AND IRRIGATION

Good open ditches do not afford complete underdrainage
except for a few yards on either side of them. In order to secure
thorough underdrainage through the use of open ditches, they must

FlQ. 50. — A good outlet ditch. This was dug with a floating dredge. It is 20 feet wide
at the top and 7 feet deep. (Wisconsin Station.)

be dug about every four or eight rods; but many open ditches
take up considerable space, they cut farms and fields into incon-
venient and irregular shapes, they require the building of many

A B C D

FIG. 51. — Covered drains other than tile. A, B, C, cobblestone and rock drains ; D, pole drain.

farm bridges, they are unsightly, they are difficult and expen-
sive to keep open and clean, they present a constant source of
danger to farm animals, they provide harborage for obnoxious
weeds, and are excellent breeding places for injurious and dis-
agreeable insects.

TILE DRAINS MUST HAVE FALL 117

Covered Drains. — The only way to eliminate the objections to
many small open ditches is to use covered drains, among which
may be mentioned tile drains, cobblestone drains, rock drains and
pole drains (Fig. 51). Cobblestone, rock and pole drains are not
commonly used, except in certain localities where these materials
are available. They are usually of short duration, because
they become easily clogged. The universal covered or under-
drain is tile, and because of its importance, it shall be given
special consideration.

TILE DRAINAGE

Drain Tile. — Drain tile are pipes usually of circular form from
one to two feet long and varying in diameter from three to thirty
inches (inside measurements). Most drain tile are made of
burnt clay; some are made of cement. When well made, tile are
very durable. Clay tile have been in operation on a farm in New
York since 1837; and in France some have been in use 200 years
and more.

How Tile Are Laid. — (Fig. 52). Drain tile are laid end to end
in narrow trenches and covered. A drain constructed by placing
tile end to end in a trench is called a "line of tile." It is quite
necessary that they be laid deep enough to escape tillage tools,
to give deep underdrainage, and to escape freezing, if possible.
In clay the usual depth is three feet, in sandy soils four and one-
half feet. Occasionally conditions do not permit their being laid
more than about two or two and one-half feet deep. In peat and
muck soils tile should be laid especially deep (four and one-half
feet and more), because these soils settle rapidly after they are
tile drained. On some marshes the settling of the peat brought
the tile so near the surface that they had to be taken up and
laid deeper.

The size of the tile to use depends upon the amount of water to
be removed. It is a safe rule to follow not to use smaller than five-
inch tile.

The digging of a trench for a line of tile is always begun at
the outlet, and it is generally necessary to lay the tile as soon as
the bottom of the trench is made ready, although it is better to
finish the trench and start laying the tile at the upper end, or head.

Tile Drains Must Have Fall.— Every line of tile should be so
laid that water entering it at any point will flow to the outlet.
This descent or fall of a line of tile is called the "gradient." It is

118

LAND DRAINAGE AND IRRIGATION

desirable to have a gradual fall of three inches in 100 feet if pos-
sible. On flat areas, one and one-quarter inches, which is considered
the minimum grade, is frequently used. It is important to remem-
ber that the less the fall or gradient, the bigger should be the tile.
When a good fall is apparent, it is comparatively easy to lay
tile so that they will carry off the water properly. On level ground
however, much care should be exercised in securing sufficient fall.

Fia. 52. — Samples of drain tile and the necessary tools used in constructing systems of
tile drainage. (Wisconsin Station.)

The level is the common instrument used in determining the
amount of fall.

Some experienced tilers determine the grade by the flow of
the water in the trench before the tile are laid.

Tile may be properly laid on a level area through the use of
grade lath (Fig. 53). For example, a line of tile 600 feet long
is to be laid, and it can be given a depth of four and one-half feet
at the outlet. To give this line a fall of two inches in 100 feet
the tile must be laid three and one-half feet deep at the upper end
of the line. Two stakes (a, 6) are driven about three and one-half

DISTANCE APART TO LAY LINES OF TILE

119

feet apart, one on either side of the proposed trench at the outlet,
and a lath (c) is nailed to them horizontally one foot from the
ground (from top of lath), which would be five and one-half feet
from the proposed grade line (0, X), or the bottom of the trench.
Two other stakes (d, e) are driven in a similar manner at the upper
end, and a lath (/) is nailed to these two feet from the ground,
which would likewise be five and one-half feet from the grade line.
Other pairs of stakes are driven in line with the first ones at inter-
vals of about 100 feet and to them lath are nailed horizontally
and in line of sight over the top of the laths " (c) " and " (/) . " The
trench is now dug until the top of a stick five and one-half feet
long held vertically on the bottom of the trench is in line with the
top of the laths. In this way a perfect grade can be obtained,

Grade L/ne

FIG. 53. — The use of grade lath in laying of tile. D, outlet ditch; N, proposed outlet for
tile; OX, proposed grade line. (See page 117.)

because the line of sight over the laths is parallel to the proposed
grade line.

On extended flat areas it is necessary to lay tile deep at the
outlet and shallow at the upper end, in order to secure sufficient fall.

On all large areas, especially if they are level or nearly so, it
is best to secure the services of a competent drainage engineer
to lay out the system of drainage and to supervise its construction.

Covering the Tile. — As soon as the tile are laid, sufficient
amount of soil should be shoveled in to cover them, and to hold
them in place until the trench is filled. Covering and anchoring
the tile in this manner is called "blinding."

Filling the trench may be done by hand, or by the use of a
plow or a scraper.

Distance Apart to Lay Lines of Tile. — Frequently a single line
of tile is all that is necessary to drain a narrow wet strip. In
draining a narrow, wet depression (draw) between two areas of
high land, it is often best to lay two lines of tile, one at the foot
of each slope, or one on each side of the lowest center line. On all

120

LAND DRAINAGE AND IRRIGATION

broad, flat areas several lines of tile are necessary. Just how
far apart these drains should be placed to secure adequate drainage
depends largely on the character of the subsoil. In some very
heavy soils and in springy areas, it is necessary to lay them not
more than two rods apart, while in porous and open soils they may
be placed as far apart as eight to twelve rods. In ordinary
loams and silt loams, and in peat and muck, four rods is the
common distance.

=20 RODS

M, main;

FIG. 54. — Natural systems of tile drainage. Three systems in an 80-acre field.
L, lateral; S, sub-main. (Wisconsin Station.)

How Tile Works. — Water gets into tile drains through the joints
between the tile (Fig. 59). In case of porous tile, a little water
goes through the walls, but at least ninety-five per cent enters
through the joints. Care should be taken in laying tile not to
leave cracks between them so big as to permit soil to fall in, yet
not so close together as to exclude the water. In tight clays it is
well to " blind" the tile with black soil to facilitate the entrance of
water. In sand it is necessary to blind the tile with black soil
to keep the sand from entering.

It is a mistake to think that thorough underdrainage is harmful
to crops, particularly in dry seasons. Tile cannot "draw" water
out of soil, nor can they drain a soil too thoroughly. It is impos-

THE NATURAL SYSTEM

121

sible to remove the capillary, or the useful water, by tiling; it is
only the free or harmful water that is drained out. Tile may
drain somewhat deeper than the depth they are laid. The capil-
lary rise of water may cause the water-table to drop below the tile.
Drainage during the wet period may cause the water-table to drop
lower during the dry period than it would if no water had been
removed. The deeper root development encouraged by early
drainage compensates for this apparent loss.

Systems of Tile Drainage. — A tile system simply means the
arrangement of the lines of tile designed to drain any particular
area. Usually tile systems are made up of " mains," "laterals"

Qrocfs
^— * -«

!

Xi

1

~4 rods

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\ • 'rail .Kn 100

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, t

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j3v/y«

1

a

' %

r

\

v

^i-ti/f '6- tile

FIG. 55. — The gridiron or parallel system of tile drainage. Troublesome outlets are
avoided by having several laterals discharge into a single main. A line of tile is located at
the edge of the high land to cut off seepage. (Wisconsin Station.)

and "sub-mains " (Fig. 54). A main carries and discharges the
water from an entire system. A lateral is a single branch drain
into which no other line of tile discharges. One or several laterals
may discharge into a "sub-main" which, in turn, empties into
a main. }

The water of the areas to be drained and the slope of the land
necessarily call for different systems of tile drainage, of which
four are generally recognized — the "natural" system, the "grid-
iron" or "parallel" system, the "herringbone" system and a
"combination" of two or all three of these systems.

1. The Natural System. — When an irregular area is to be
drained, the laterals and sub-mains have varying directions, and
they must necessarily join the main in an irregular manner (Fig.
54). This is called the "natural" system.

122

LAND DRAINAGE AND IRRIGATION

2. The Gridiron or Parallel System. — When an area requiring
several lines of tile slopes uniformly in one direction, or when it
slopes uniformly towards two adjacent sides, the "gridiron" or
''parallel" system is the most economical (Fig. 55). This system
may also be used on level areas.

3. The Herringbone System. — Sometimes land slopes towards
a middle and lower area. In such a case the " herringbone "
system is most convenient (Fig. 56). This system may like-
wise be employed on level areas.

Fia. 56. — A combination of three systems of tile drainage. A, natural system; B, parallel
system, C, herringbone system.

4. Combination of Systems. — In actual practice it is usually
necessary and convenient to combine the different systems of
drainage, since conditions vary even in comparatively small areas.
Figure 56 illustrates this.

Outlets of Mains Should be Protected. — Exposed outlets of
mains should be constructed to withstand frost, flooding or washing
and tramping of livestock. Moreover, they should be protected
by a screen to prevent their becoming clogged by anything that
might enter the mouth of the drains. Generally, it is best to use
glazed sewer pipe for about six to ten feet at the outlet, laid in
firm soil, or imbedded in concrete (Figs. 57 and 58).

Tile Cheaper and Better Than Open Ditches. — In the long run

TILE COMBINED WITH A SURFACE-RUN

123

it is best and less expensive to drain with tile than with open
ditches whenever possible. With a few exceptions, an open ditch
smaller than six feet deep, three feet wide at the bottom, and fifteen

Fro. 57. — The two protected outlets to the drainage system on this marsh of 125 acres
Two steel pipes screened by iron rods.

FIG. 58. — An open ditch should be deep enough to permit tile to empty into it. With
few exceptions, an open ditch smaller than six feet deep, three feet wide at the bottom, and
fifteen feet wide at the top, has no excuse for an existence. (Wisconsin Station.)

feet wide at the top, has no excuse for an existence; large tile
should be used instead, or a surface-run combined with tile will
work best.

Tile Combined With a Surface-Run. — In constructing this

124

LAND DRAINAGE AND IRRIGATION

combination it is usually better to make the surface-run at one
side of the tile after the tile is laid and when the land is dried
sufficiently to permit horses to work (Fig. 59). When completed,
the surface-run carries the water during flood flow, while the tile
works throughout the year.

Cult/voted

. — Tile combined with surface-run. The surface-run carries the water when there
is a flood, while the tile works throughout the year. (Wisconsin Station.)

Tile Drainage is Profitable.— (Figs. 60 and 61.) It costs from
twenty to forty-five dollars an acre for complete tiling, but the
benefits to be derived far exceed the cost, as is shown by the four
typical examples in the following table:

Cost and Benefits of Tile Drainage

Acres

Conditions before drainage

Cost of
drainage

Conditions after drainage

90

A 60-acre field was poor

$2,200

Pasture improved 300 per

pasture, and a 30-acre

cent. The 30-acre field now

field was cultivated, but
most of the crops failed

grows six times the amount
of grain as formerly, and no

failures

16

Was worthless for pasturing

$ 700

Fine corn, clover and other

and cultivation

crops are now produced

40

Grew willow brush

$1,000

Now grows most excellent

corn

240

Land was of little value for

$2,360

Splendid crops of hay and

pasture, and it produced

grain have been raised since

no hay

drainage. The value of one

crop offsets cost of tiling

Vertical Drains. — Some vertical drains consist of openings or
cracks in underlying bed-rock, and cracks or openings made in
hard-pan 4 by the use of dynamite. It sometimes happens that a

4 A hard and impervious substratum is commonly called a hard-pan.
It may vary in thickness from a few inches to three feet and more.

VERTICAL DRAINS

125

sinkhole, or a cavern in the underground rock, affords a splendid
outlet for a system of tile drainage.

FIG. 60. — Can any good thing come out of this marsh full of brush, cat-tails, reeds, and
rushes? (See Fig. 61.)

Fia. 61. — Corn that will fill the silo to good measure has been grown on the same marsh
as shown in Figure 60, after being properly drained.

Now and then a drilled well, or one dug and filled with stones,
furnishes the only possible means whereby water in basins can be
drained out. Not all wells made for such a purpose prove success-
ful— this one may fill with water, while another may bring to

126

LAND DRAINAGE AND IRRIGATION

the surface even more water. The successful ones never fill, no
matter how much water may drain into them.

The most common vertical drains consist of ordinary drain tile
placed in the ground vertically, end on end (Fig. 62). It should
be remembered that the only conditions under which such a drain
can work are : first, a porous or gravelly stratum should underlie the

impervious hard-pan or sub-
soil ; and, second, that stratum
should be dry so that the drain-
age water may flow away.

Drainage by Means of
Pumps. — The drainage of
many low-lying lands is made
possible only through the use of
pumping machinery to lift the
drainage water over levees into
adjacent streams or other drain-
age channels. The drainage of
such areas is done by open
ditches and tile — but all the
drainage water discharges into
reservoirs, and from them it is
pumped over the levees. This
kind of drainage, though suc-
cessful in a number of the Euro-
pean countries, is but little

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developed in the United States.
One of the most interesting

FIG. 62.— A vertical drain. A porous or pumping drainage projects
gravelly stratum should underlie the impervi- .-, j TT i

ous hard-pan or subsoil, and the water must known IS the great Haarlem

have a chance to flow away. (Wis. Station.) Lake Q£ Holland Until 1852j

this lake was fifteen feet deep and covered about sixty-five square
miles. Now this area, formerly a lake, is traversed by well-
improved highways and is occupied by about 20,000 people. In a
similar manner the Dutch Government (1913) authorized the
undertaking of the complete reclamation of about 781 square
miles of what is now the southerly portion of the Zuider Zee.

IRRIGATION

Irrigation Is the Artificial Watering of Land. — It is the opposite
of land drainage. Irrigation is commonly thought of as a practice

OBJECTS OF IRRIGATION 127

confined to dry regions, but this is not necessarily the case. In
arid climates, irrigation is absolutely necessary to produce any
crops at all, while in semi-arid sections, irrigation, where possible,
makes crop production sure, and greatly increases the yield.
In sub-humid and even in humid regions, because of the irregulari-
ties in the time and amount of rainfall, irrigation is practiced to a
greater or less extent. Both China and Japan, for example, have
a large and a well distributed rainfall, yet irrigation is generally

FIG. 63. — Furrow irrigation in orchard in dry climate. (U. S. D. A.)

practiced. In Japan alone, water is artificially applied to at least
12,500 square miles of land, or about two-thirds of her culti-
vated area.5

Objects of Irrigation. — The primary object of irrigation is to
supply needed water to crops. Without irrigation, many thou-
sands of square miles of land in the world would be deserts instead
of fit places to live in; and hundreds of square miles of desert
wastes are today being made to produce bountiful harvests just
by supplying water to these thirsty lands.

In the United States irrigation is confined largely to the western
states, where many large irrigation projects are in operation or

6 "In China and Japan, where they must raise large crops or starve, they
have been compelled to irrigate, although they have a larger summer rainfall
than we ... but they also fertilize heavily." — King.

128 LAND DRAINAGE AND IRRIGATION

under construction, bringing under cultivation millions of acres.
According to the Thirteenth Census, there are in all about
14,000,000 acres of irrigated land in the continental United
States (Fig. 63).

Irrigation or flooding proves beneficial and necessary in growing
certain crops, such as rice and cranberries.

On irrigated lands flooding is extensively used to moisten
fields preparatory to plowing; and flooding, instead of tillage tools,
is frequently employed to firm a seed bed prior to planting.

In some sections irrigation is extensively practiced, supple-
menting a good and evenly distributed rainfall, to make highly
fertilized lands produce the highest possible yields. This is espe-
cially true in densely populated countries, like China, for example.

In some places irrigation is the means whereby fertilizing
material is carried to the land — sewage from great cities like Paris
and Edinburgh, for example. In several countries the water of
rivers is used to fertilize meadows, and, in most cases, to supply
needed water at the same time.

How Irrigation Water is Secured. — Before any area of land can
be irrigated a source of water must be -provided. The most
common sources are rivers. In such cases, a portion of the river
water is diverted and conducted by means of canals, conduits and
huge pipe lines to the area to be reclaimed, where it is turned from
the main canal to branch canals which carry the water to the farms
to be irrigated, to which it is delivered by still smaller branches.
It is interesting to read about or to see some of the wonderful
engineering feats accomplished in some of the great western
irrigation projects (Fig. 64).

Other sources of irrigation water are lakes, large reservoirs
made by constructing dams across gorges or narrow valleys, and
flowing wells. Water may also be secured by pumping it from
wells, streams and canals.

How Irrigation Water is Applied. — There are four ways in which
irrigation water may be applied to land — by flooding, through
the use of furrows, by spraying, and by subsurface irrigation.
Flooding and the furrow method are the two approved methods
of irrigation in irrigated sections. Whichever method is used
depends upon the character of the soil, the lay of the land, the kind
of crops, the water supply, and the "head," or the volume of water
supplied to the unit of time. Under some systems of irrigation
management, farmers are given large streams of water for short

FURROW IRRIGATION

129

times, and under other systems, they are given small streams for
longer periods.

1. Flooding. — Flooding is a method of surface irrigation. The
water applied covers the whole surface of a field either as a thin
sheet of running water, continued until sufficient water has soaked
into the ground, or as a sheet of standing water which is allowed
to remain until the soil has absorbed enough. Flooding is usually
practiced when the land is not too sloping and when irrigation

i.

FIG. 64. — Roosevelt Dam, Salt River, Arizona. One of the big dams of the world.
Date of construction, 1905-11. Approximate cost, $10,000,000. Used to irrigate 219,000
acres. (U. S. Reclamation Service.)

water is abundant. It is commonly done on fields cropped to
small grains, alfalfa, and grasses.

2. Furrow Irrigation. — Furrow irrigation is a second method of
surface watering. By this method the water is guided over the
land in furrows, or channels, which traverse the whole field —
the water covering only a part of the soil surface. Furrow irriga-
tion is one of the most common methods, and is one of the best for
all conditions. When crops like potatoes, corn sorghum and
sugar beets are grown, it is usually best to irrigate by the furrow
method after the crop is on the ground. This is also the commonly
adopted method of all orchard irrigation (Fig. 63).

9

130

LAND DRAINAGE AND IRRIGATION

3. Spray Irrigation. — Spray irrigation is the process of applying
water to the surface of soils or to crops in the form of small drops,
spray or mist. The first systems of spray irrigation were the out-
growth of city lawn and garden sprinkling. It was soon found that
through such spraying, small amounts of water could be applied
advantageously to delicate crops, especially for supplementing
an uncertain rainfall.

The water used is conveyed to the field under pressure through
pipes or hose. This system of irrigation is well adapted to those
conditions in humid sections which demand small and frequent

Fia. 65. — The Skinner system of irrigation. A field piped for overhead spray irrigation.

(U. S. D. A.)

applications of water in the preparation of the soil for transplanting,
and for supplying quick-growing, market-garden crops and berries
with the moisture they so much need for best growth, and especially
to keep them thriving during dry periods (Fig. 65).

4. Sub-irrigation. — Underground or subsurface irrigation im-
plies that the irrigation water is applied from below the surface.
This may be accomplished through the use of open ditches and
underground tile, or pipes of iron, concrete, or wood.

The open ditch method of sub-irrigation has proved successful
to a limited extent in western America and in Florida.

The underground pipe system of irrigation has not met with
success, except under exacting soil conditions found in only a
few localities. At Sanford, Florida, the same tile used in sub-
irrigation also serves for drainage during wet seasons.

PROFITS IN IRRIGATION FARMING 131

Irrigated Farms Require Good Management. — Farms in irri-
gated sections require cultivation and good management as do
farms in humid regions. It has been found that cultivation after
irrigation is very effective in conserving the soil moisture. Weed
control is another important consideration. The diversification
of crops on individual farms and in each irrigation section, and
the production of livestock, should be given careful attention —
not only to utilize labor effectively, but to help maintain
soil fertility.

Maiiy Irrigated Lands Need Drainage. — At first thought it
seems strange, especially to one unfamiliar with irrigation condi-
tions, that irrigated lands should need drainage. Nevertheless,
some areas, either directly or indirectly, have been converted into
swamps by irrigation; other areas have become water-logged and
are unproductive; still other irrigated lands have passed from a
state of high productivity to a condition fit only for wet pastures.
Often the result of over-irrigation is manifested in an accumulation
of alkali salts on or near the surface without any apparent wet
condition. Other areas not irrigated also require drainage. Deep
underdrainage is necessary and is the only possible means whereby
these lands may be reclaimed.

Aside from the objects sought in draining any soil, the thorough
underdrainage of some of these irrigated lands has an important
additional object; and that is, to provide an outlet for the down-
ward moving water used to dissolve out the harmful alkali salts.
For irrigated areas, drains of clay or shale tile are the best. The
tile should be hard-burned, impervious, and free from foreign
ingredients so they can withstand the harmful action of the
alkali salts.

Other Irrigation Problems. — Irrigation farming has many
features quite different from farming without irrigation. Aside
from the problem of water supply, application of water, and the
other problems already mentioned, there are many others that an
irrigation farmer must either solve for himself or have solved for
him. These problems relate to the best methods of irrigation
under particular conditions, to the economic use of water, to the
amount of water best for different crops, time best to apply water,
frequency of application, the maintenance of soil fertility, etc.
Much information on these points is available, but lack of space
here prohibits further discussion.

Profits in Irrigation Fanning. — It costs more to produce crops

132 LAND DRAINAGE AND IRRIGATION

under irrigation than under rainfall. It follows, therefore, that
the farmer's profits must be less with irrigation than without,
unless the yields are larger or the prices he receives for his produce
are higher. The prosperity of some of the irrigated sections of
the West has been more largely due to increases in the value of
land than to the profits in growing crops. This may also be said
of many sections in humid regions.

According to some investigations made on irrigated farms in
Utah and in an irrigated section in Montana, the average farmer's
labor income6 on these farms seems to compare favorably with the
average labor income received by farmers of other states.

Irrigation an Art of Antiquity. — When we learn of the advance-
ments that have already been made in reclaiming arid lands in
the United States, and of the almost magic transformations
resulting from irrigation, we cannot but wonder at it all, and com-
ment on the wonderful age in which we are living. Yet, when we
consider the remains of canals and certain other ruins of ancient
lands, including what is now Southwest United States — ruins
which give us but a glimpse of the elaborate systems of irrigation
operated by ancient and prehistoric peoples — we reflect the same
sentiment expressed nearly three thousand years ago by that
wise oriental king — " There is no new thing under the sun." The
art of irrigation has thus come down to us as a prehistoric heritage
to be improved by succeeding generations.

Demonstrational Exercises. — Material Needed. — 2 large baking-powder
cans; 2 cubic feet of sandy soil; a thermometer; 3 three-inch clay tile; 2 10 X
12 X 10-inch wooden boxes.

To Demonstrate That a Warm, Spring Rain Warms a Well-drained Soil
Quickly, While a Saturated Soil Remains Cold. — Procedure.— Fill 2 large
baking-powder cans within one-quarter inch of the top with a sandy soil.
One can should be water tight and the other should have the bottom perforated.
Saturate and flood the one soil with cold water. Bring the other soil to the
same temperature by passing cold water through it. Determine the tempera-
ture of the two soils. Now pour on each soil at least one-half a pint of warm
water. (The warm water will pass through the drained soil but will run off
the other.) Take temperature readings again and record results.

Questions. — (a) Explain why warm spring rains do not warm saturated soils.

(6) Why do warm rains warm cold well-drained soils most effectively?

(c) Name other benefits of good underdrainage.

6 In comparing the profitableness of different systems of farm management
or in determining the profits in farming, the farmer's "labor" or "managerial
income" is the most convenient and accurate basis. Labor or managerial
income means profits above total costs — total costs including interest on money
invested and unpaid family labor.

QUESTIONS 133

To Demonstrate How Tile Works. — Procedure. — Obtain three 3-inch
clay or shale tile and two water-tight wooden boxes about 10 X 12 X 10 inches.
Cut two holes in each box in opposite sides near the bottom, large enough to
allow the tile to enter. Place one tile in the first box so that the two ends
will project from either side. Place the other two tile end to end, with the
joint in the middle of the box and the ends of the tile projecting from opposite
sides of the box. Make both boxes water-tight by means ot paraffin or paint
(do not seal the joint between the tile in the box containing the two tile)
and fill each box with sandy soil. Saturate the soil in both boxes with water
and note results.

Questions. — (a) How do tile work under field conditions?

(6) Are there any objections to the use of glazed tile?

(c) About what per cent of the drainage water passes through the walls
of the tile?

Laboratory Exercises (optional). — Material Needed. — Ditching spade; tile
hook; a number of tile; a few laths; a drainage level; and whatever other tools
found necessary.

To Construct a Trench for Drain Tile. — The teacher can determine the
method of procedure.

To Become Familiar With a Drainage Level. — The teacher should deter-
mine the need of such an exercise, and plan sufficient work to meet the needs.

Field Studies. — Observe wet areas, especially those due to seepage. Note
the conditions of the subsoil.

Observe any system of drainage: open ditches, systems of tile drainage,
outlet, results, benefits, etc.

QUESTIONS

1. What is meant by land drainage?

2. Why do crops suffer when water stands too long on a field?

3. Name other harmful effects of the lack of drainage.

4. Name and discuss the benefits of thorough drainage.

5. Give reasons why some lands are wet.

6. Discuss the need of land drainage in the United States.

7. How may wet lands be drained? Describe briefly the different methods,
• and conditions under which used.

8. What is the first step in draining land? How may this information

be obtained?

9. What can be done with a spade in land drainage?

10. How can plow furrows serve as drains? Illustrate by a diagram or sketch.

11. What is a surface-run? What is its use and how made?

12. Explain the uses of open ditches in land drainage.

13. What are the objections in constructing many small ditches? How can

these objections be overcome?

14. What is meant by tile drainage? What are drain tile?

15. How are tile laid, and how deep?

16. What is meant by "line of tile"? Gradient? What relation is there

between gradient and the size of tile to use?

17. How may the grade line be determined in digging the trench for tile?

Explain by use of diagram the use of grade lath.

18. What is meant by "blinding" tile?

19. How far apart should lines of tile be laid?

134 LAND DRAINAGE AND IRRIGATION

20. Explain why it is often best to lay two lines of tile in a wet draw between

two areas of upland.

21. How do tile work? Can land be too thoroughly drained? Explain.

22. Explain and illustrate by use of a diagram what is meant by a system

of tile drainage, mains, laterals, and sub-mains.

23. What are the systems of tile drainage commonly used? Illustrate each

by diagram.

24. Why is it best to have one instead of many outlets to a system of

tile drainage?

25. What is the smallest ditch that should, under most conditions, be con-

structed? Explain.

26. Is drainage profitable? Give an example.

27. What are vertical drains? Describe by use of a diagram the conditions

under which a vertical tile drain can work.

28. How is it possible to drain low-lying and flooded lands?

29. Describe a drainage system which you have seen installed.

30. What is the meaning of irrigation? To what kind of climate is irri-

gation confined?

31. Give the objects of irrigation.

32. What are some of the sources of irrigation water?

33. Name and describe the methods of irrigation.

34. Do irrigated farms require less attention than farms not irrigated?

35. Why do some irrigated lands need drainage?

36. What are some of the special problems that confront the irrigation farmer?

37. Is irrigation farming profitable?

38. Who invented the art of irrigation?

39. Describe an irrigation system which you have seen.

CHAPTER X

TILTH AND TILLAGE

FROM earliest times it has been the experience of husbandmen
that cultivated plants grow best in soils that are stirred or tilled.
In this modern age good tilth, good seed bed and intertillage are
especially emphasized as important factors in successful crop-
production. Good tilth is one of the factors determining fertility;
and it has been defined as that physical condition of the seed bed
with respect to mellowness and firmness that is favorable to plant
growth (Chapter V). This condition is developed largely
through tillage. A good seed bed is not merely a layer of very
loose, fine soil; it consists, rather, of the tilled portion of the ground,
loosened and pulverized until it is mellow, and at the same time
possessing a fair degree of firmness (Fig. 66) . The proper prepara-
tion of the seed bed is fundamentally important in securing good
yields of practically all farm crops; and, in case of crops planted
in rows, subsequent cultivation, or intertillage, is indispensable.

Factors Determining Good Tilth. — The development of good
tilth, or of a good seed bed, depends largely upon three factors:
(1) the moisture content of the soil when worked; (2) soil struc-
ture, and (3) the kind of tillage tools used.

Any one who has ever operated a tillage tool knows that soils
pulverize and work best when they contain a proper amount of
moisture. Each farmer must determine for himself just when
the soils on his farm are in fit condition to work.

The easy workability of soils of a sandy and crummy structure
is well known. Heavy soils of compact structure require the most
attention and effort to get them into good tilth. The crummy
structure of the heavier soils depends largely upon the amount
of organic matter they contain, since the organic matter binds the
soil particles into crumbs or granules. It is a common experience
with some farmers that certain soils are much more difficult to
work and pulverize now than years ago, for the reason that the
organic matter has been largely removed or used up, and too little
attention was given to maintain or increase it through the growth
of grasses and clover, and through the use of manure. The fre-
quent growing of grasses and clover on heavy lands greatly aids

135

136

TILTH AND TILLAGE

in changing the structure of such soils, because the fine roots and
other organic matter prevent the individual grains from running
together. This explains why sod ground and some black, crummy
soils can be plowed when quite wet without any appreciable harm.
When the roots and organic matter are used up, the soil loses its
acquired looseness and crumbly characteristic. Even sandy soils
till better when they contain a good supply of organic matter.
Because of its influence on soil structure and on tillage, the organic

r

FIG. 66. — An excellent seed bed prepared for alfalfa.

matter of soils should be maintained, and in many soils, increased
if possible.

Tillage Tools. — Numerous kinds of implements have been
devised to prepare the ground for planting, and especially to care
for many of the crops during early growth. There are many differ-
ent kinds of plows, harrows, rollers, clod crushers, weeders and
cultivators. Aside from these there are many seeding and planting
implements which in themselves perform various tillage opera-
tions in addition to sowing the seed.

Frequently the real purpose of a tillage implement, or the
principle upon which it is built, is overlooked; and too often a
machine is purchased merely because of some new device, or some
extra lever, rather than on the quality of the work it can do, or

PRINCIPLES GOVERNING TILLAGE

137

because of its adaptability to the soil in which it is to be used.
It should be remembered that every good implement is designed
to do a certain kind of work, and, in most cases, in a particular way;
and each one is built with certain adjustments so that it can be
regulated to meet varying conditions.

The " How " of Tillage Depends Upon the " Why."— When the
specific objects of tillage are kept in mind, and the principles
governing the methods of tillage are clearly understood, there can
be little difficulty in deciding upon the kinds and types of machines
to use, and when best to operate them.

The Objects of Tillage. — The objects of tillage are: to loosen
and pulverize the soil, to deepen the seed bed, to crush lumps and
break crusts, to turn under coarse litter and vegetation, to com-
pact the seed bed, to kill weeds, to enable soils to catch and thus
store more moisture, to conserve soil moisture, and to mix fertil-
izers and other materials into the soil. Two or more of these
objects may be accomplished in one operation.

Principles Governing Tillage. — Some of the principles govern-
ing tillage may be stated as follows:

(a) A mellow and firm seed bed is necessary to favor ger-
mination, and to enable young plants to develop good, strong
root systems.

(6) The liberation of plant-food elements through the action
of organisms and other agencies is favored when soils are well
aerated. Aside from drainage, tillage promotes the exchange of
air in soils.

(c) The fact that capillary water in soils rises from soil particle
to soil particle makes it necessary that the soil particles within
the seed bed and between the seed bed and the subsoil be in close
contact with each other (Chapter V).

(d) Since soil moisture readily evaporates when the surface
soil is firm and compact, it is essential that a soil mulch be developed,
wherever necessary and practicable, to check or lessen this loss of
moisture (Chapter VIII).

(e) Heavy, compact soils can be made to trap and thus store
more moisture when they are loosened, plowed or subsoiled.

(/) The natural, crummy structure of the heavier soils may
be easily destroyed when they are worked too wet. This creates
a "puddled" condition which is unfavorable to plant growth.

(g) Weeds should be destroyed.

In the following paragraphs these objects and principles are

138

TILTH AND TILLAGE

considered in relation to the different tillage implements. It is
convenient to divide the discussion into three parts: (1) Prepara-
tion of the seed bed; (2) seeding and planting, and (3) cultiva-
tion and intertillage.

PREPARING THE SEED BED

The Plow the First Implement. — The first tool commonly used
in the preparation of the seed bed is the plow. Because of its
importance, it has been called the greatest tool in the advance-
ment of agriculture. Long before the invention of the modern
plow, tillers of the ground so fully realized the great necessity of
some kind of implement to loosen the soil preparatory to planting

FIG. 67. — Diagram illustrating the pulverizing action of the moldboard. (King.)

that many of them used a crooked, wooden stick. A modern
moldboard plow is a comparatively plain tool and seems a simple
invention, yet the history of its evolution reads like a romance.

Because of its ingeniously devised steel moldboard, the modern
plow can turn practically any kind of soil, and at the same time
pulverize it more or less (Figs. 67 and 68). Certain equipment is
required to increase the efficiency of the plow; such as, jointers
and coulters, to cut sod into strips so it can be turned and to aid
in turning under weeds, grass and litter; the gauge wheel, to aid
in regulating the depth of plowing;: and clevises, for draft
adjustments (Figs. 69 to 74).

Plowing Stubble Land. — Stubble land, or old ground, is land
on which small grains and cultivated crops have been grown.
Plows designed for such lands are called stubble plows. Their
moldboards are short, high and have an abrupt turn. Because of

PLOWING STUBBLE LAND

139

FIG. 68. — The work of the plow. The center of this plowed area is the back furrow.

FIQ. 69. — The way a good plow does its work. When one becomes interested in the action
of the plow, plowing ceases to be a drudgery.

140

TILTH AND TILLAGE

this type of moldboard, the soil is thoroughly pulverized when
turned — provided it is in fit condition to be plowed (Figs. 71
and 72-1).

FIG. 70. — The parts of a plow: a, moldboard; b, share; c, point; d, shin; e, handles;
/, beam; g, brace rods; h, standard; i, landside; /, jointer; k, gauge wheel; I, bridle; m, beam
clevis; n, hitch clevis; ot clamp; p, heel.

FIG. 71. — First prize stubble plowing.

Plowing Sod. — The only way to turn a prairie sod, or any old,
tough, grass sod, is to use a prairie-breaker type of plow (Figs. 72
and 79). This type is built with an easy-turning moldboard
which turns the furrow slice over flat, against the preceding one

PLOWING SOD

141

FIG. 72. — Three types of plow bottoms: 1, stubble bottom; 2, general purpose; 3, sod.

B

A

FIG. 73. — Adjustment of coulter. A, ordinarily set coulter one-half inch from landside
(c). In deep plowing or for sod one-quarter inch. Secure a full furrow slice to keep shin
covered with dirt. B, set middle of rolling coulter about three inches back from point. In
loose or trashy soils, one or two inches back. In hard or sticky soils, about four inches back.

• • * o 74-— Different types of coulters and jointers. Note proper
jointer; 2, rolling coulter; 3, blade coulter or hanging cutter; 4, fin coi
combination rolling coulter and jointer; 6, knee cutter or coulter.

adjustment. 1,
coulter or cutter: 5,

142

TILTH AND TILLAGE

without breaking it very much, and in a way which facilitates
the decomposition of the sod.

Ordinary sod is turned best with a sod plow, or one having a
moldboard adapted for either sod or stubble (Figs. 72 and 78).
The moldboards of such plows are somewhat longer, and turn the

Fia. 75. — Wrong way of plowing sod. (Humid farming.)

furrow slice more slowly than those of the stubble plows. Sod
turned properly is much more easily made into a good seed bed
than when poorly or improperly plowed (Figs. 75, 76 and 77). A
stubble plow, under average conditions, cannot turn sod the way
it should be turned (Figs. 78 and 79. Compare with Fig. 77).

FIG. 76. — Right way of plowing sod. (Humid farming.)

When Disk Plows Are Used. — Some soils, because of their con-
dition or peculiar characteristics, can be plowed successfully only
with a disk plow; these are dry and hard, sticky, waxy or gumbo
soils, and other soils in which a moldboard plow will not scour l
(Fig. 80). The disk plow may be used on stubble land when the
depth of plowing is five or more inches. It is not recommended for

1 Moldboards, disks, cultivator shovels, drill shoes and hoes should always
be kept clean and free from rust when not in use. Most farmers use axle
grease to keep them from rusting. Frequently plows refuse to scour simply
because their moldboards were allowed to rust.

WHEN DISK PLOWS ARE USED

143

FIG. 77. — What happens when sod is plowed with a stubble plow.

Fio. 78.— First prize sod plowing.

It is not so tiring, sir, to plow well,

For your mind is interested. (English Plowman.)

sod or light, loose soils when it is desirable to plow less than five
inches deep. The moldboard plow is recognized as a universal
plow. The disk plow is brought into service only when the mold-

144

TILTH AND TILLAGE

board plow cannot be used. The disk plow may be used success-
fully in plowing loose peat soils.

Fio. 79. — A prairie breaker.

Best Time to Plow. — The best time to plow depends largely
upon the object to be attained. Since nearly all plowing is done
in the fall and spring, it would be well to consider here a few
important points concerning fall and spring plowing.

Fio. 80. — One type of disk plow.

Fall Plowing. — Usually farmers find it convenient to plow in
the late fall, because farm work then is not so pressing as in other
seasons; moreover, the congestion of work in the spring is much
relieved when the plowing is done at this time. When soils are
to be plowed deeply, or when the seed bed is to be deepened, late

FALL PLOWING

145

fall plowing is best. This results in less loss of nitrogen through
leaching, and in the development of a firm seed bed. Furthermore,

Fia. 81.— Subsoil plow.

FIG 82. — A subsoil plow in action.

Fia. 83. — The work of a subsoil plow.

j when any "raw" subsoil is turned up, it becomes thoroughly
weathered before planting time.
10

146 TILTH AND TILLAGE

Other advantages of late fall plowing are: (a) It favors the
development of granular or crummy structure, and hence good
tilth, in lumpy and heavy soils; (6) many crop pests are destroyed,
such as white grubs and aphis; (c) coarse litter turned under is
permitted to decompose partially, thus establishing better contact
between the seed bed and the subsoil, and providing a better
supply of available plant-food elements; (d) soils plowed in the
fall are seldom too wet.

Fall plowing is usually best for wheat, and is commonly
practiced when corn follows sod.

In dry-farming sections it is often best to plow immediately
after a grain crop is harvested; for two main reasons: (a) the soil
plows better because of the moisture it contains, and (6) soil
moisture is conserved.

In some sections farmers hesitate to plow much of their
'young" sod land in the fall, because if they do, they may be
left without any hay land the next season if, perchance, the new
or spring seeding is winter-killed.

Land that is fall plowed should be left rough, unless it is plowed
early and sown to a cover crop or winter grain.

Spring Plowing. — Usually much plowing is done in the spring,
largely because time does not permit all of it to be done in the fall.
At this time of the year there is much danger of plowing some of the
heavier soils when too wet. This is harmful, because the crummy
structure of the soil is destroyed, and a " puddled" condition
results. This explains why some heavy silt loams, clay loams and
clays are so hard and lumpy. A puddled soil is not necessarily
mud. When a wet clay, for example, is worked, the crumbs, if
any, are broken up and the soil particles run together, forming an
impervious mass; in other words, the clay is puddled. On drying
the mass becomes hard. The action of the plow is sufficient to
produce a puddling effect when a heavy soil is plowed too wet.

Spring plowing is best for sands that are subject to "blowing."

Late spring plowing permits the plowing under, for soil im-
provement, of green crops which ordinarily do not make suffi-
cient growth in the fall to turn under at that time. Rye is a
good example.

Moderately Deep Plowing Best. — In general, best results are
secured when soils are plowed moderately deep — from six to nine
inches. In a deep seed bed most plants develop deep, strong root
systems, thus enabling them to secure a good supply of moisture

SUBSOILING AND DEEP TILLING

147

and plant-food elements. On deep, rich soils deep plowing is not
absolutely necessary. On the better soils it is not necessary to
plow deep for small grains — three to four inches is usually better
than six inches. On the poorer soils fall plowing to a depth of six
inches for grain is often more desirable than shallow spring plowing.
For corn, and especially for the sugar beet, a deep seed bed is to
be preferred.

Deep hillside plowing is frequently recommended for fields
that wash easily (Fig. 84). This causes much of the rainfall to
soak into the ground, thus checking or lessening the run-off. All
hillside plowing should be done at right angles to or across the slope.

FIG. 84.— Hillside plow. (Walking type.)

New or virgin lands seem to produce best when initial plowing
is comparatively shallow. Since in such soils the helpful soil
organisms necessarily inhabit a shallow surface zone, too deep
plowing buries them so deep that they cannot properly perform
their function in making plant-food elements available.

It is good farm practice to vary the depth of plowing from year
to year. If a soil is always plowed at the same depth, the tramping
of the horses and the weight of the plow on the furrow bottom
tend to compact and harden it, causing the formation of a so-called
" plow-sole." This danger is greatest in wet clay soils. A plow-
sole is detrimental because it retards or prevents percolation,
entrance of air and root penetration.

Subsoiling and Deep Tilling. — Plows have been built to stir the
soil at greater depths than can be accomplished by the^common
plow. These implements are called subsoilers and deep-tillers
(Figs. 81, 82 and 83). A subsoil plow is used when the subsoil is
so compact that water and roots cannot penetrate it. This imple-

148 TILTH AND TILLAGE

ment follows the common plow, and cuts a thin, deep gash in the
bottom of the furrow; thus loosening the subsoil without mixing
it with the surface soil. Subsoiling is not a general practice in
humid farming, since results do not seem to warrant the extra
expense, except under unusual conditions. The subsoiler should
never be used in light, sandy loams, sand or gravelly soils.

Deep tilling through the use of other plows designed for this
purpose generally do not give the returns above the extra cost to
encourage this practice.

Fro. 85. — " Striking out a land " with a two-bottom gang plow.

Dynamiting Soils. — Dynamite has been used in some places
to break up and loosen impervious subsoils to facilitate the entrance
of air, water and roots. Though it proves a good practice, when
necessary in tree planting, its general use is still an open question.2

More About Plows and Plowing. — Special plows are designed
for hillside plowing (Fig. 84). The bottoms of the walking types
swivel for right- and left-hand furrows, and the sulky types consist

2 Subsoiling, deep tilling, and soil dynamiting are all operations that
increase the expense of production over that of ordinary plowing. Experi-
ments conducted in both dry-land and humid farming all lead to the conclusion
that yields cannot be increased nor the effect of drought overcome by tillage
below the depth of ordinary plowing. — Jour. Agril. Research, Sept. 9, 1918.

PLOWING DOES NOT MAKE A SEED BED 149

of two bottoms, a right-hand and a left-hand plow. The use of
these plows enables the operator to work back and forth across
the field, throwing the furrow slices all the same way. He ascends
the hill as he progresses and leaves no back furrows (Fig. 86)
or dead furrows.

While the walking plow is still used by many farmers, the sulky
type is coming into general favor. With its modern improvements
the sulky plow lessens the draft, is simple to operate, and saves the
strength of the operator.

1

FIG. 86. — The first round. The back furrow.

The gang plow is also becoming a common implement (Fig. 85) .
With such a plow one man can operate two or more bottoms, and
it can be drawn with horses or a light tractor. This helps to solve
the labor problem. The three-bottom gang is a common light-
tractor plow, though on the smaller farms the two-bottom gang
is usually preferred. On large prairies, where immense tracts are
farmed, ten, twelve and fourteen-bottom, large-engine plows
have been in use (Figs. 87 and 88).

Plowing Does Not Make a Seed Bed. — Seldom can a seed bed
be properlypreparedthroughplowing only — other tillage operations
are necessary, depending on the condition of the plowed ground,
the kind of crops to be grown, and the method of fertilization.

TILTH AND TILLAGE

FIG. 87. — A three-bottom tractor plow at work.

£:

FIQ. 88. — A 14-bottom big engine plow in action.

AFTER PLOWING, HARROWING

151

Just what to do to complete the preparation of the seed bed
depends largely upon how clearly the farmer understands what
constitutes a good seed bed, or good tilth.

FIG. 89.— The full disk harrow.

FIG. 90.— A double disk harrow. Cutaway disk in rear. T, truck or forecarriage.

After Plowing, Harrowing. — The implements commonly used
after the plow are the disk and smoothing harrows (Figs. 89, 90,
91 and 92). No other tillage tool can pulverize the soil so thor-
oughly and quickly as the disk harrows. Of these, the full disk is in
most general use. When the ground is very hard, stony, or when
it is tough sod, the cutaway disk is especially good. The spading

152

TILTH AND TILLAGE

disk harrow is frequently used on fields infested with quack grass,
to bring the roots to the surface. It is always best to lap the disk

Fia. 91. — A spading disk.

FIQ. 92. — The smoothing harrow. (Drag.)

harrow half to get best results in pulverizing fall plowed lands, sod
or lumpy soil — except when two disk harrows are used in tandem.
The degree of pulverization depends upon the angle at which the
disks are set.

SPRING TOOTH AND ACME HARROWS

153

Commonly, the disk harrow is all that is required to prepare
a good seed bed for small grains on potato and corn land. For
weeding and summer fallowing3 these machines are indispensable.

Sometimes it is desirable to use the disk harrow on land before
it is plowed; to break up the surface crust or lumps, to cut up
and work trash into the seed bed, and to conserve moisture.
When disking is done for the first two reasons, the furrow slice
comes into more intimate contact with the subsoil.

When the seed bed has been made sufficiently mellow or loose
through disking, the smoothing or drag harrows are used to give
the finishing touches.

Flo. 93. — Acme harrow.

Spring-Tooth and Acme Harrows (Figs. 93 and 94).— The
spring-tooth harrow is a most efficient tool on rough and stony
ground, and on new land in wooded sections. It may also be used
instead of the disk harrow, for pulverizing sandy and gravelly soils;
and it may be used effectively in alfalfa fields to loosen the soil and
eradicate weeds and grass. It is a more effective tool than the spike-
tooth harrow.

The Acme or blade harrow is used to a considerable extent in
some sections for pulverizing, compacting and for killing weeds.
This machine gives best results on loamy soils free from stones.

3 Summer fallowing is the tilling of uncropped land during the summer.
This may be done with the plow or narrow. The common objects of summer
fallowing are : to kill obnoxious weeds, to store rainfall of one year for the
next, and to conserve moisture.

154 TILTH AND TILLAGE

Flankers. — Sometimes, as in tobacco culture, and in market
gardening, the planker is used when it is desirable to leave the
surface particularly even and finely pulverized without firming it

FIQ. 94. — Spring tooth harrow.

(Fig. 95). This tool is usually made out! 'of three to four eight-
inch or ten-inch planks bolted together with their edges overlapping.
The planker is not a compacting implement.

FIG. 95. — Planker.

Rollers and Clod Crushers. — Lumps are easily broken by means
of rollers and clod crushers (Fig. 97). Very often, after harrowing,
the seed bed is too loose or has not sufficient contact with the sub-
soil. If such be the case, rolling is necessary to compact the soil.
Of all tools used for this purpose there is none better than the cor-

ROLLERS AND CLOD CRUSHERS

155

rugated roller, or, as it is often called, the cultipacker (Fig. 96).
This machine crushes lumps, compacts the soil and at the same
time leaves a thin mulch in the form of a corrugated surface.

FIG. 96. — The corrugated roller or cultipacker.

Whenever a smooth or drum roller is used, it should be followed
by a light spike-tooth harrow, with the spikes tilted, to form a
mulch to conserve the soil moisture.

FIG. 97.— Three other types of rollers. A, pipe or tee bar roller; B, smooth or drum roller;
C, crowfoot pulverizer (roller).

Muck, peat, sand, sandy loams and many loose silt loam soils
are especially benefited by a cultipacker. When muck and peat
soils are made firm they warm up quicker than when left loose.

The roller should never be used on the heavier soils when they
are wet, but rather when they are in good working condition.

156

TILTH AND TILLAGE

SEEDING AND PLANTING

Soil conditions determine largely the different methods and
types of machines used in seeding and planting; and the prepara-
tion of the seed bed is a most important factor in getting seeds
well planted.

Good Seed Bed Favors Planting. — The advantages of a firm
seed bed thus far discussed have been in relation to the germinating
seed and the plant. Another advantage in having a firm seed bed
is, the depth of planting can be easily controlled. Too often,
grain, for example, is planted too deeply because little or no con-

FIG. 98.— Press drill.

sideration is given to the looseness of the soil. If a drill is set to
sow at a depth of one and one-half inches and the wheels sink down
three inches in the loose soil, then the seeds are dropped at a depth
of four and one-half inches. Grain seeds planted so deep may die
for want of sufficient air, the stems may meet with too much
resistance and never get through, or the food stored in the seed
may become exhausted before the shoots reach the surface.

Planting Seeds in Close Contact With Soil. — The importance of
having good contact between the seed and the soil, or having
the soil pressed on the seed, is emphasized in the fact that corn
planters, beet seeders, cotton planters and other planting machines
are provided with press wheels. The use of water in transplanting
is not only to supply easily available water, but also to cause the
soils to come in close contact with the roots. Press grain drills
and press-wheel attachments for the ordinary grain drills are also

DRILLS VS. BROADCAST SEEDERS 157

in use (Fig*. 98). Such grain drills are recommended for sandy
soils and when trouble is experienced in planting, due to high winds
blowing the soil and displacing the seed. In either case, the soil is
pressed firmly on and around the seed; thus making germination
more sure, and, in case of blowing, the seed with the soil pressed
around it is held more firmly. Other drills are shown in Figures
99 to 101.

It is especially desirable to have excellent tilth when sowing
grass seeds. Usually when alfalfa is to be sown broadcast on loose,
loamy soils, best results are secured when the ground is rolled

FIG. 99. — Single disk grain drill.

after harrowing or disking, then "dragged" with a light, spike-
tooth harrow, the seed sown, the land dragged again to cover the
seed, and finally the seed bed rolled with a corrugated roller. This
provides a fine, firm seed bed, insures proper depth of planting,
creates good contact between the seed and the soil, and provides
a thin mulch to lessen evaporation. If an alfalfa drill is used, then
only the roller is necessary after seeding.

Drills vs. Broadcast Seeders. — There are two classes of grain
sowers— drills and broadcast sowers. Compare Figures 100 and 101.
Of each of these there are several types. In some sections, farmers
have definite knowledge as to which kind is best and most economi-
cal; while in other localities much difference of opinion prevails.

The drill has several advantages over the broadcast sower, viz..
the seed can be planted at a uniform depth, less seed is required,

158

TILTH AND TILLAGE

yields are better, and grass, clover and alfalfa have a better chance
when grain js sown in drills. In general farming, the single disk
drill is the most common, because it can do first-class work in any
soil capable of being seeded. Many soils do not permit a satisfac-

FIG. 100. — Broadcast grain sower.

tory use of the shoe drill, because the shoes do not scour. On
stony ground and in breakings full of roots, the hoe drill gives
especially good results.

Broadcast sowers are in general favor in the oat and corn
sections (Fig. 100), and many are in use elsewhere. These imple-

A B

FIG. 101. — Two other types of grain drills. .4, hoe drill; B, shoe drill.

ments scatter the seed on the ground, and some other machine
must follow to do the covering. Some of these machines are broad-
cast sower and cultivator combined (Fig. 105) . Here the seed is scat-
tered over the loosened soil and is covered by the cultivator teeth.

Many farmers, especially those in the oat sections, simply
broadcast the seed on unplowed and undisked corn land, then cover
the seed by disking. This is possible only where soils are fertile

WHEN DISKING IS BETTER THAN PLOWING 159

and where they seldom become hard and compact. This may seem
a careless way of farming to those unfamiliar with the conditions
encouraging this practice, yet it proves economical and gives
good returns. Disking the corn or potato land to a shallow
depth before broadcasting is the common practice with many
farmers, and this is considered better than when no disking is
done before seeding.

Fia. 102. — Lister.

When Disking is Better Than Plowing. — When oats are to be
sown on potato or corn land in a high state of fertility, disking
proves better than plowing. Many farmers have found that
they can also grow better barley when the land is disked instead
of plowed. This is especially true on black, crummy prairie soils,
and crummy silt loams on many dairy farms. It is the experience
of many dairy farmers that oats and even barley stand up better
when such lands are not plowed.

Listing is primarily a method of planting corn in dry sections

160 TILTH AND TILLAGE

particularly in the southern and southwestern states where light
soils predominate, and where hot and dry weather often prevails
during the growing season. The seed is planted in the bottom of

FIG. 103. — Work done by a lister. (Kansas Station.)

furrows made by a lister or middle-breaker, and later on, the fur-
rows are rilled by cultivation after the corn is up. This method

FIG. 104. — Middle-breaker, or middle-buster.

enables the roots to penetrate the soil deeply, and insures a better
moisture supply (Figs. 102, 103 and 104).

One method of listing corn is to fall plow, give the land a fair
amount of disking or cultivation in the spring, then plant by
using a machine which is a lister and planter combined. Another

CULTIVATION TO CONSERVE MOISTURE 161

way is to list the land in the fall — and in the spring, the corn is
planted in the furrows made by opening the previously made
ridges or beds. The opening of the ridges is done by a lister or
middle-buster. The middle breaking and planting are commonly
done at the same time by the combination lister and planter.
Frequently corn is planted with such a combination machine with-
out any previous preparation of the land. Especially is this true
when corn follows corn or cotton.

Cotton is commonly planted in furrows in a similar manner
as listed corn.

FIG. 105. — Broadcast seeder and cultivator.
CULTIVATION AND INTERTTLLAGE

Cultivation, in its broad sense, means the act of tilling — but it
is commonly understood to mean tillage done by cultivators.
There are some tools designed to cultivate the land before planting,
others that cultivate to cover the seed sown by them, and still
others are designed for alfalfa fields (Fig. 105). The ordinary
cultivators, however, are used for intertillage.

Why Crops Are Cultivated. — The objects of intertillage are
commonly given as: (1) to kill weeds; (2) to conserve moisture,
and (3) to aerate the soil.

In humid farming it is generally recognized that the killing
of weeds is the primary importance of cultivation. This is espe-
cially true on soils in good tilth, and when frequent rains occur
(Chapter VIII).

Cultivation to conserve moisture is good practice in all dry-land
farming, and in sand management. On silt loams in humid
11

162

TILTH AND TILLAGE

sections conservation of moisture and aeration are sometimes
questioned, because different results have been attained under
different conditions. A few of these results are of interest.

In Illinois. — On the common corn-belt soil of Illinois (brown
silt loam) the following nine-year averages in corn were obtained :

Method of cultivation

Yield per acre

(a) Land plowed, seed bed prepared, weeds allowed to grow
(6) Land plowed, seed bed prepared, no cultivation, weeds

kept down by scraping with hoe
(c) Land plowed, seed bed prepared, cultivated 3 times

7.4 bushels
48.9 bushels

H
43..S bushels

In Minnesota, during a dry year, the following corn yields
were secured on a " black loam soil containing considerable sand":

Method of cultivation

Yield per acre

(a) When all weeds were allowed to grow

(6) When weeds were cut with hoe without stirring soil

(c) When cultivated 6 tunes (3 times each way)

0.4 bushels
45.8 bushels
50.6 bushels

In Wisconsin. — On a heavy silt loam (Miami) the following
results were secured during a year in which no beneficial rain fell
during the period between July 3 and August 12:

Method of cultivation

Yield

per acre
(corn)

Rated
quality
of corn

Character
of growth

(a) Land plowed, seed bed prepared, weeds
kept down with a sharp hoe, soil not
stirred in the least.
(6) First two cultivations 3.5 inches deep;
subsequent cultivation shallow, and
as often as was necessary to kill weeds
and maintain a good mulch.

44.6
bushels

74.8
bushels

70

per cent

99.5
per cent

Uneven

Excellent
and uniform

During a dry summer following a wet spring (1916), the follow-
ing results were obtained in growing soybean hay in rows on sand
at Hancock, Wisconsin. Very little rain fell between June 30
and August 15.

Method of cultivation

Yield of hay
per acre

(a) No cultivation, but weeds were cut with a hoe; soil stirred
the least possible.
(6) Frequent cultivation

1875 pounds
3660 pounds

CULTIVATORS

163

Most farmers know the value of cultivation if for no other
reason than to kill weeds; and when this is well done, the soil is
usually kept well mulched and aerated. Crops on heavy soils,
in particular, should receive careful attention in regards to culti-
vation. Too often cultivation is done as a matter of routine.
Some plan to go through their corn, or other fields, three times or

FIG. 106. — A 6-shoveled sulky cultivator.

four times, with no thought as to the proper time in which it should
be done, and with little thought as to why.

Cultivators. — Intertillage may be done through the use of sev-
eral types of cultivators — each type designed to do its work in
some particular way or to meet particular soil conditions. The
shovel cultivators are the universal or most common implements.
Of these, the six- or eight-shoveled sulky or riding cultivator has
met with greatest favor, because of its general adaptability (Figs.
106 and 107). Many prefer the three-shoveled gang, while others
the four-shoveled. Many different styles of these and other types
of cultivators are made, each with various adjustments.

164

TILTH AND TILLAGE

The spring-tooth gang cultivator (Fig. 108-A) is a very effective
tool and it can be used under varied conditions, though in the
heavier soils cultivators with rigid teeth do better work as a rule.

The surface cultivator gives good results in loamy soils and
when they are comparatively dry (Fig. 108-C). In soils free from
stones the blades may be sharpened to cut such weeds as thistles,
quack grass, etc. When soils are comparatively moist, this machine
does not stir the soil sufficiently to cover and kill small weeds,
because the soil simply slides over the blades and the tiny weeds
are but little disturbed.

FIG. 107. — A two-row riding cultivator.

The disk cultivator is quite commonly used in some localities.
They do not seem to meet with general favor, though many were
purchased when they first appeared on the market (Fig. 108-B).
This type of cultivator is looked upon by some as a fad.

Lister cultivators are made especially for listed corn for first
cultivation (Fig. 108-D) . The ordinary two-horse, shoveled culti-
vator is used for the later cultivating.

Many styles of walking cultivators are in use (Figs. 109 and
110). In some sections these are generally used, while in others
the common walking type is used when corn becomes too high for
the sulky. Walking cultivators are especially favored by gardeners.

When to Cultivate. — The best time to kill weeds is when they
are small or when the seeds are germinating. In order to do this

WHEN TO CULTIVATE

165

at the proper time the farmer must observe closely and often the
condition of the different fields. Growing weeds may be killed

FIG. 108. — Other types of riding cultivators. A, four-shovel, spring-tooth gang; B, disk
cultivator; C, surface cultivator; D, single row lister cultivator.

through cultivation in three ways: (a) They may be loosened
and exposed to the drying sun; (b) they may be covered and

FIG. 109. — Two types of walking cultivators. 4. seven-shovel one-horse cultivator;
B, fourteen- tooth cultivator.

smothered with soil, and (c) they may be cut off or covered with
soil to prevent their manufacturing any food. In the last one,
much diligence and close watching is required. Some prefer to

166

TILTH AND TILLAGE

kill obnoxious weeds in the third manner by summer following,
quack grass and Canada thistles especially.

Cultivation to conserve moisture should be done before the
land is allowed to dry out. A good mulch should be prepared
at the beginning of a dry period.

Fio. 110. — Two other types of walking cultivators. A, four-shovel; B, two-shovel cultiva-
tor, or double shovel plow. B is a cultivator commonly used in the South.

Crops on heavy soils are best cultivated, especially for the first
time, when the moisture conditions are right. When this is done
subsequent cultivations are made much easier because a layer of
well-loosened soil prevents baking.

Some soils, particularly the black lowland silt and clay loams,
shrink considerably when they dry out causing big cracks to form.
Such lands should be cultivated frequently to prevent as much
as possible the formation of these cracks, and to fill them when they
do occur (Fig. 111).

LEVEL CULTIVATION GENERALLY BEST 167

Shallow Cultivation Gives Best Results. — In humid farming
results in general are in favor of shallow cultivation. The only
time when it is safe to cultivate deep at all is when the plants are
very young, and before they send their feeding roots into the
surface soil. Much harm results in deep cultivation (four to five
inches), in cutting these feeding roots. The only way to determine
whether or not cultivation is too deep is to investigate what the
cultivator teeth are actually doing. If the shovels next to the row

•T

FIG. 111. — Cracks like these are moisture chimneys.

are going too deep and cutting the roots, they may be raised ; and
if all the teeth are doing injury they should be set for more
shallow work.

Level Cultivation Generally Best. — Hilling corn does not
increase the yield, hence level cultivation is more desirable. In
some localities hilling the corn is a common practice because it
has always been the custom. A farmer gets the hilling habit when
he allows the weeds to get ahead of him. It then becomes neces-
sary to throw much dirt on the rows in order to cover the weeds.
If this must be done, and in some instances it is necessary to cover
such weeds as the wild morning-glory later cultivation should be
done, if possible, at right angles to the ridges to level them. In

168 TILTH AND TILLAGE

this respect planting corn in check rows is advantageous. Because
of the action of the shovels, proper cultivation leaves a slight slope
between the rows.

The high hilling of potatoes has no particular advantage.
When this is done more surface is exposed and hence more moisture
is lost through evaporation. When potatoes are grown on the
heavier, compact soils, digging is made easier when they are
ridged a little; and, moreover, the throwing of some loose dirt

FIG. 112.— Walking weeder and its work.

on the hills becomes necessary as the potatoes advance in growth
to protect the tubers from sunburning, since in many silt loams
the growth of the tubers causes cracks to form around the hill,
which let in the light.

Weeders. — (Fig. 1 12) . The weeder is a weed-killing and mulch-
ing tool consisting of many narrow spring teeth. It is adapted for
killing very small weeds in corn, potatoes, etc., either before or
after the plants are up. This is not an effective tool when weeds
are quite large or when the ground is at all hard or heavy.

A light, spike-tooth, smoothing harrow is often used in place
of a weeder.

QUESTIONS 169

Emergency Tillage Operations. — Sometimes it is not convenient
to compact the seed bed or break lumps before planting. In this
case, if the soil is still too loose or lumpy/ grain and even corn land
may be rolled after the crop is up. This should be done when the
plants are small.

When grain is grown on heavy soils, it is best to leave the seed
bed covered with a layer of small, loose lumps. This is not so favor-
able for the formation of crusts as in case of finely pulverized soil.

Heavy rains often pack the soil so firmly after the crop is
planted that hard crusts form, which prevent the penetration of
shoots and stems. A spike-tooth harrow is often used to break
the crust, and sometimes a roller gives best results. Beans often
break their necks in trying to get through a hard, crusty soil. In
such a case the hoe or the careful use of a cultivator is best to
break the crusts.

Home Experiments and Projects. — To Demonstrate That it Pays to Culti-
vate corn.

Procedure. — Secure a small plot of ground, preferably heavy, silt loam
(about J4 acre), and divide equally into three parts. Treatment up to culti-
vation time should be the same on all plots. Plant each plot to the same kind
of corn. Give the corn on plot No. 1 thorough cultivation, and maintain a
good mulch especially during dry periods. Plot No. 2 is to receive no culti-
vation at all, but all weeds should be kept down with a sharp hoe. The soil
should not be stirred in the least. All weeds should be allowed to grow in
plot No. 3. At harvest time cut out the row between adjoining plots. Dis-
card. Determine yield of corn on acre basis. Keep cost accounts to ascertain
comparative profits. (During seasons of frequent and sufficient rains, but
little difference may result in yields on the first two plots. It would be best
to continue this project for at least 3 or 4 years.)

To Determine the Advantage, if any, in Hilling Corn. — Procedure. — Select
14 rows of corn in a corn field. Practice level cultivation on seven of
the rows and hill the other seven rows. Discard the middle row, and determine
comparative yields. What are some of the disadvantages of hilling?

Field Studies. — Examine different plows, harrows, cultivators, rollers, and
planting machines. Study their action in relation to the soil.

It would be well, if possible, to compare the work of a stubble plow in
plowing sod with that of a sod plow.

QUESTIONS.

1. What is the relation of good tilth to soil fertility? Give the meaning of

good tilth.

2. What constitutes a good seed bed? What is intertillage?

3. Name and discuss the factors influencing the development of a good

seed bed.

4. Name the common tillage tools. What should guide the farmer in his

purchase of tillage and planting implements?

5. What are some of the common objects of tillage?

6. State some (eight) of the principles governing tillage.

7. What is the use of the plow?

170 TILTH AND TILLAGE

8. Name the parts of a common walking plow. What is a jointer? Coulter?

Illustrate by sketch the proper adjustments of jointers and coulters
(Fig. 74.)

9. Describe the pulverizing action of the moldboard; illustrate by diagram

or otherwise.

10. How does stubble plowing differ from sod plowing?

11. What constitutes good plowing? (Figs. 68, 71, 76, 78, and 87).

12. What is a disk plow and when is it used? Why are they not recommended

for light, loose soils?

13. Name some of the advantages of late fall plowing. Disadvantages. Whv

leave fall plowed land rough?

14. What is a puddled soil?

15. Discuss spring plowing— advantages and disadvantages.

16. Why and when is deep plowing generally best? When is shallow plow-

ing best?

17. Why is it not good practice always to plow at the same depth? What is

a better way?

18. What is subsoiling? Is it generally recommended? Why? What about

deep tilling?

19. How may dynamite be used in connection with tillage?

20. What is a hillside plow and how used? What are gang plows—

their advantages?

21. What are harrows? Name and describe the use of the different typss.

22. What is meant by summer fallowing?

23. What is a planker and for what is it used?

24. Name and describe the common rollers or clod crushers. When should

they be used? When not? What is a precaution to observe in the use
of a smooth or drum roller?

25. Why are light, loose soils especially benefited by cultipackers?

26. What are the advantages of good tilth or a firm seed bed in relation to

planted seeds and growing plants? Discuss another advantage in having
a firm seed bed.

27. What has been the effect of the principle of good contact between the

seed and the soil on the construction of many planting and seed-
ing machines?

28. What is a good program to follow when alfalfa is to be sown broadcast

on loose, loamy land?

29. Which is better to use for sowing grain — drills or broadcast sowers? Do

all drills give the same satisfaction? Explain.

30. Under what conditions is disking better than plowing for grain, particu-

larly oats? Why?

31. What is listing? Where and how is it done? What is a "middle-buster"?

32. Give the meaning of cultivation. What are cultivators?

33. Name and discuss the objects of intertillage.

34. Name and discuss the use of the different implements used in intertillage.

35. What should guide the farmer as to what particular tool to use, and how

and when to cultivate?

36. What is the depth of cultivation best for humid farming? Why?

37. How is a farmer to know when he is cultivating too deep?

38. Wliat machine adjustments may be made to eliminate injury in cultivation?

39. Discuss level cultivation and hilling.

40. What are weeders, and when do they prove effective tools?

41. Does it injure grain or corn if it is necessary to roll land when the plants

are small?

42. How may crusts be broken after crops are planted?

43. Have you ever known of cases of harrowing small grain while young?

What were the results?

44. For an outline summary of this chapter, see table of contents.

CHAPTER XI

SOIL ORGANISMS IN RELATION TO SOIL FERTILITY

IN Chapter II it was stated that millions of organisms live in
the soil, and that many of them bring about changes that are
fundamentally important in determining fertility. These many
organisms may be classed as bacteria, fungi, yeasts (Fig. 113),
algae (al'je), worms, insects, and rodents. The first three groups
are classed as "microorganisms" because they are of microscopic
dimensions. The majority of the bacteria are not more than

A

FIG. 113. — Other soil organisms. A, a common mold; B, yeast plants.

0.0000197 of an inch in diameter, and it is believed that some are
too small to be seen with the aid of the most powerful microscope.
In one-third of a thimbleful (one gram) of normal field soil have
been counted from 140,000,000 to 400,000,000 microorganisms;
and in manured soil, as high as 750,000,000. The most tiny ones
(bacteria) are in greatest abundance, and it is they which play a
large part in nature's plans, and stand in close relationship to
the practices which make possible successful crop production.

In this chapter will be considered in particular three groups of
the helpful soil organisms, viz.: (a) Those which cause decomposi-
tion or decay; (6) those which cause nitrification, and (c) those
which gather nitrogen from the air.

ORGANISMS OF DECOMPOSITION

Microorganisms Clear the World of Trash (Fig. 114-A).—
What would this world be were it not for the fact that all plants

171

172 SOIL ORGANISMS IN RELATION TO SOIL FERTILITY

and animals finally disappear after they die? If this were not so
the world long ago would have become choked with dead material.
Most of the rubbish of the earth is buried in or is thrown upon the
soil, and through decay, it is reduced to the fundamental elements,
becoming again the dust of the earth, water and gases. This decay
is the work of many kinds of microorganisms, particularly the
bacteria and fungi. It is a wise provision of nature that all organic
matter can again break down into the elements of which it is com-
posed, since through these changes sustenance is provided to pro-
long the life on the earth and to make possible new life.

a c

FIG. 114. — The important soil bacteria. A, common bacteria causing decompo-
ition; B, nitrifying bacteria ; C, nitrogen-fixing bacteria; a, free nitrogen-fixing; b, nodule

Sltl

bacteria.

No Crops Without Decay. — Soils continue to weather1 after
they are formed from rocks; and because of weathering, crops are
able to secure from the mineral rock particles the mineral elements
so necessary for their growth. But crops also require nitrogen —
and the nitrogen in the soil is held there, not in the mineral par-
ticles, but mainly in complex, insoluble compounds in the form
of organic matter. Crops cannot absorb this organic matter any
more than they can consume the mineral particles of the soil.
Before plants can secure any nitrogen from this organic matter,
and before any crops can be grown successfully at all, the organic
matter must first undergo decomposition. Herein myriads of
microorganisms do a most important work.

Crops Secure Mineral Elements From Two Sources. — At the

1 Weathering is a broad term meaning the breaking up and decay of
material things wrought by natural forces. Decay of soil is largely the result
of chemical forces acting independently or through the aid of microorganisms.

NITRIFICATION EXPLAINED 173

same time that the nitrogen compounds in the soil organic matter
pass through the changes necessary to provide available nitrogen,
the mineral elements, which this organic matter contains, likewise
become available. Thus a crop such as corn, for example, secures
its supply of nitrogen from one main source — the soil organic mat-
ter; and its supply of mineral elements from two sources— from the
mineral soil particles and from organic matter.

Decay of Organic Matter Aids Decay of Mineral Particles. —
The organisms which cause the decomposition of the soil organic
matter perform a two-fold work. They not only bring about the
necessary changes in the organic matter to provide available
nitrogen and mineral elements for use by plants, but in an indirect
way they aid in the liberation of mineral elements contained in
the mineral soil particles. This is explained through the fact
that in all organic decay, acids are formed which are effective
agents in dissolving mineral matter. We can now understand more
clearly why it is important to maintain a good supply of organic
matter in soils to enable crops to secure needed and sufficient
elements. It is significant that rich, garden soils usually have a
high content of organic matter, and that they are much more
abounding in life than ordinary field soils. We can explain, too,
why some light-colored soils rich in all the important mineral
elements and having a low productive power, can be made to pro-
duce much larger yields simply by plowing under a good growth
of green rye.

Some Fertilizers Valueless Without Decay. — Were it not for
the organisms of decomposition, fertilizers such as tankage, blood
meal, cottonseed meal, etc., would be of little or no value. More-
over, some insoluble mineral fertilizers, such as rock phosphate,
would be practically useless, but for the presence of decomposable
organic matter in the soil, or because of the organic matter in
which the fertilizer may be mixed when applied. Rock phosphate
has been found to give best results in most soils when it is mixed
with manure or plowed under with green rye or clover.

NITRIFICATION

Nitrification Explained. — The accompanying diagram (Fig.
115) is helpful in gaining a clear idea of the meaning of nitrification.

This diagram explains that the nitrogen in organic matter is
held there in the form of complex, insoluble compounds which
must be broken down, through decomposition, into simpler com-

174 SOIL ORGANISMS IN RELATION TO SOIL FERTILITY

pounds, and much of it finally into ammonia (gas) before the
nitrogen can be converted into available form suitable for plants.
This breaking-down process is brought about by fungi as well as
by bacteria. As soon as the ammonia is formed, other bacteria,
called nitrifying bacteria or nitrifiers, convert it into soluble
nitrogen-containing salts, called nitrates.2 This conversion of
ammonia into nitrates by nitrifying bacteria (Fig. 114-B) is termed
"nitrification." The opposite of nitrification is denitrification,
which means the breaking down of nitrates by certain organisms
which work only when the air is shut out of the soil. Under good
soil management we need not concern ourselves about this destruc-
tion of nitrates.3

What Becomes of the Nitrates Formed. — Nitrification is
usually most rapid during the growing period. The nitrates then
formed are almost completely and immediately absorbed by the
growing crops, unless too much is manufactured. If no crops are
present to utilize the nitrates, or when too much is formed, they
are leached out of the soil and lost. Ordinarily more nitrates are
produced in a rich, cultivated soil than are used by the crop.

An idea as to the rate at which nitrification goes on in some
soils may best be gained by studying the nitrogen needs of good
crops of corn, sugar beets, and cabbage. During cold weather
nitrification ceases.

The Use of Catch and Cover Crops. — Since certain crops are
harvested early, some soils are left bare during the fall months.
It has been found that much nitrates are formed during this time
and lost from the soil. To conserve this nitrogen, rye or some other
crop is sown immediately after the harvesting of these early crops.
Such crops are commonly called " catch" or " cover" crops. They
not only prevent nitrogen losses, but they prevent soil washing and
blowing, and improve the soil when plowed under. In the South,
rye, either alone or with hairy vetch or crimson clover, is frequently
sown as a winter cover crop. In cultivated orchards, the most
common cover and catch crops are rye and clover.

2 Ammonia is a gas composed of one atom of nitrogen and three atoms of
hydrogen, hence the chemical formula, NH3. The strong smell of washing
ammonia-water is due to this gas.

The last stage of decomposition in which ammonia is formed is called
" ammonification."

3 It is to be noted that the decomposition is a breaking-down
process, and nitrification is a building-up process. A common nitrate formed
in soils is calcium nitrate [Ca(NOs)2], which is a more complex substance
than ammonia.

NITROGEN FIXATION BY NODULE BACTERIA 175

Nitrification Means Loss of Organic Matter. — The bacteria
engaged in nitrification do not add one atom of nitrogen to the soil
supply; they simply change insoluble forms of nitrogen jnto soluble
forms which are either used by plants or are leached from the
soil. This explains in a large measure how the soil organic matter
is used up; and it also emphasizes the necessity of maintaining a
good supply of this material in soils as a source of easily available
mineral elements as well as of nitrogen.

ORGANIC MATTER

(containing complex, insoluble
nitrogen compounds)

Nitrates ' = soluble salts containing nitrogen

;\ (Plants absorb these salts)
\ Nitrified f/on= the con version of
j ammonia into nitrates by
) nitrify inj bacteria.
Ammonia (<]Qs)

FIG. 115. — Diagram illustrating nitrification.

Some Soils Lack Nitrifying Organisms. — Some peat and muck
soils, on being reclaimed through drainage, fail to produce satis-
factorily even though mineral fertilizers be supplied. Such results
are sometimes due to a lack of " available" nitrogen, in spite of
the fact that these soils may be well supplied with, or are composed
almost entirely of, organic matter. Decomposing and nitrifying
organisms may be lacking. Since good manure, especially horse
manure, contains myriads of these kinds of organisms, they may
be supplied to such soils through manuring. This explains in
part the beneficial effect of manure, as a first treatment, to many
peat and muck soils.

NITROGEN FIXATION BY SOIL BACTERIA

Nitrogen Fixation by Nodule Bacteria. — For many years
scientists were puzzled to know three things: (a) Why a clover
plant could grow perfectly well when no available nitrogen was

176 SOIL ORGANISMS IN RELATION TO SOIL FERTILITY

supplied to it; (6) why legumes, that is, such crops as clover,
peas, beans, etc., should enrich the soil considerably in nitrogen,
and (c) why a crop like wheat or turnips, for example, should pro-

i

FIQ. 116. — Nodules on the roots of soybean. (Wisconsin Station.)

duce much larger yields on clover sod than when grown on such a
sod as timothy.

It was known centuries ago that certain plants had bunches or
nodules on their roots; and it was known for forty years that
these nodules contained bacteria. Yet it was not until 1886 that
two German investigators proved conclusively that these bacteria
within the nodules actually have the power of taking the free

NITROGEN FIXATION BY NODULE BACTERIA 177

FIG. 117.— Crimson clover nodules. (U. S. D. A.)

FIQ. 118. — Nodules on roots of medium red clover. (Wisconsin Station.)
12

178 SOIL ORGANISMS IN RELATION TO SOIL FERTILITY

nitrogen from the soil air and converting it into a form suitable
for the plant (Figs. 114-C, 116, 117, 118 and 119).

There are three main differences between legumes and other
plants: (a) They are very rich in nitrogen; (6) they usually have
nodules on their roots, and (c) they may increase the nitrogen
supply of the soil through the action of the nodule bacteria.

Nodule organisms are also called "symbiotic bacteria." They
have the power of independent existence, but when they enter the
roots of legumes both the bacteria and plants are benefited by
the close association.

Nitrogen Fixation by Free Soil Bacteria. — Aside from the
bacteria which cause the formation of nodules, there are bacteria

Fia. 119.— Different forms of alfalfa nodules. (U. S. D. A.)

in the soil which have the power of fixing or gathering nitrogen
independently of any roots or plants. These are commonly called
the free nitrogen-fixing organisms, or non-symbiotic bacteria.

From what has been said it can be concluded that nitrogen
fixation in soils is the fixing or gathering of atmospheric nitrogen
by nodule bacteria and by free nitrogen-fixing organisms.

Nitrogen fixation may also be accomplished artificially through
the use of electricity.

Certain molds and algae in soils also seem to have the power of
fixing free atmospheric nitrogen.

• Nitrogen-fixing bacteria are classed as plants, as are the other
important soil bacteria.

Amount of Nitrogen Gathered. — Under field conditions it
has been estimated that the free nitrogen-fixing bacteria gather
and add to the soil annually from fifteen to forty pounds of nitrogen

HOW NODULE BACTERIA WORK

179

per acre. The amount gathered by the bacteria may vary from
forty to two hundred pounds to the acre per year, depending upon
the amount of crop growth and soil conditions. This does not mean
that the nodule bacteria actually add to the soil this amount
of nitrogen, but rather it is the amount the bacteria furnish to
the legume.

How Nodule Bacteria Work. — Nearly everyone is interested
in knowing how the minute nodule bacteria aid legumes in getting

"fe-p^Ht^

FIG. 120.— The inside of a lupine nodule, magnified. (U. S. D. A.) (See Fig. 121.)

their nitrogen. These organisms naturally live in the soil, and when
they come in contact with the legume root they enter it and grow
rapidly, causing an abnormal growth known as tubercles or nodules.
As the plant grows, the bacteria multiply and the nodules increase
in size and in number (Figs. 120 and 121). Each nodule contains
millions of these bacteria. They feed upon the plant juice and, in
return, furnish the plant with nitrogen which they take from the
air in the soil and combine it in a form suitable for the plant.
About the time seeds form on the legume the nodules cease grow-
ing, lose their plump appearance, begin to shrink, and finally die,

180 SOIL ORGANISMS IN RELATION TO SOIL FERTILITY

the bacteria returning to the soil in vast numbers. Here they may
remain for a considerable length of time before they have an
opportunity to enter other plants and again gather nitrogen
and multiply.

How the Growing of Legumes Improves Soils. — The growing
of legumes may improve soils directly in two ways: by adding
organic matter and by increasing the nitrogen content. The
amount of nitrogen that may be actually added to the soil in grow-
ing a crop of clover, for example, depends upon the soil and
especially upon what disposition is made of the crop. The crop

FIG. 121. — A few of the bacteria which fill the cells, highly magnified. (U. S. D. A.)

may be plowed under, it may be cut for hay and sold off the farm,
or it may be fed on the farm, either as pasture or hay.

In studying the clover plant, it has been found that practically
two-thirds of the total nitrogen contained in it (roots and all) is
in the hay, and one-third in the roots. Under average, normal
soil conditions, the clover gets about two-thirds of its nitrogen
from the nodule bacteria, and one-third from the soil reserve. Thus
when the crop is taken off the field, there is left in the roots practi-
cally the same amount of nitrogen as was taken from the soil
supply. The nitrogen content of the crop harvested, there-
fore, represents the amount fixed or taken from the air by the
nodule bacteria.

It follows that when a clover crop is plowed under, the soil is
enriched by the amount of nitrogen contained in the clover plowed
under. This amounts to about forty pounds for every ton of hay

CROP FAILURES 181

equivalent; that is to say, if a crop of clover that would yield two
tons of hay were plowed under, the soil would be enriched by about
eighty pounds of nitrogen per acre.

When the clover is cut for hay and sold off the farm, the field
growing the crop is not enriched. If at the start the soil were very
rich the nitrogen content would even be less after the growing of
the clover. On the other hand, if the soil were comparatively
poor in available nitrogen, a gain would result.

When the clover crop is fed on the farm, the amount of nitrogen
that may be gained is equal to the amount contained in the hay
minus the loss in feeding. When manure is well cared for, there
is a possibility of regaining about sixty per cent of the nitrogen
in the hay, or about twenty-four pounds for every ton of clover
hay fed.

What was said of clover may apply to alfalfa except that one ton
of alfalfa hay contains fifty pounds of nitrogen. Information
concerning other kinds of legumes is meager; nevertheless, it
remains true that a legume can add about twice as much nitrogen
to the soil when it is plowed under as when it is fed and the manure
returned to the land.

Certain investigations have shown that the roots of cowpeas,
soybeans, crimson clover, etc., contain a very low per cent of
the total nitrogen. Very probably when these crops are removed
from the land, some nitrogen is removed from the soil.

Clover Sod Better Than Timothy. — Under like conditions it is
well known that a corn crop, for example, on clover sod yields
much better than on a timothy sod. This is largely because
clover roots are very rich in nitrogen, and they decompose rapidly,
thus causing the liberation of a good supply of plant-food elements.

Crop Failures Owing to Lack of Nodule Bacteria. — Poor
yields, and even absolute crop failures, are not rare experiences
resulting from a lack of proper nodule bacteria. Lack of alfalfa
nodule organisms was the cause of twenty -six per cent of the
alfalfa failures studied in the south half of Wisconsin in the period
between 1912 and 1917. It is a common mistake to think that
because one kind of legume grows well on a certain soil any
other kind of legume would necessarily thrive there. This is not
the case, however, since different species of legumes require quite
different species of nitrogen-fixing bacteria. Many farmers have
experienced absolute failure in alfalfa because they thought that

182 SOIL ORGANISMS IN RELATION TO SOIL FERTILITY

since they could grow excellent clover and corn, alfalfa should
likewise do well.

It is necessary that legumes have these bacteria to help them
secure the large amount of nitrogen they demand. In exceptionally
rich soils the nodule bacteria are not so necessary, because there
the plants are able to secure their nitrogen requirement directly
from the soil. It is usually true that wherever a certain legume
has never been grown, there a lack of the proper bacteria prevails —
except in cases where the same bacteria can grow on one legume as
well as on another.

Alfalfa bacteria grow without difficulty on sweet clover, bur
clover and black medick; or vice versa.

The bacteria causing the formation of nodules on medium
red, alsike, crimson, mammoth and white clovers may be grown
interchangeably.

The nodule bacteria on the following legumes can grow on one
as well as on another: Garden, field, and sweet peas, and vetch.

Soil Inoculation. — It is a comparatively simple matter to add
to a soil the necessary legume bacteria. This process is called
"soil inoculation." Usually, whenever a particular legume is to
be grown on a field for the first time, and especially when for the
first time in that locality, it is a safe rule to inoculate the soil.
If the legume is soybean, inoculate with soybean bacteria; if
alfalfa, inoculate with alfalfa bacteria; if it is field pea, inoculate
with field pea bacteria, etc. The successful growing of the com-
mon garden pea may depend largely on proper inoculation.
(Fig. 122.)

Methods of Soil Inoculation. — Several common methods are
used in inoculating soils. Soil may be taken from one field growing
the legume successfully and applied to another field upon which
is to be grown the same legume. The soil is taken from the surface
six or eight inches. A bushel of well pulverized soil is sufficient to
inoculate one acre, though farmers usually use about a wagon-box
full for three to four acres. Usually the soil is spread by hand.
Since sunlight is a destroyer of germ life, it is necessary, if the soil
is quite dry and the sun is shining bright and warm, to harrow the
land immediately after the inoculating soil is applied.

The seed-agglutination method of inoculating for legumes is
now commonly used. Procure a peck of soil which has plenty of
the right kind of bacteria. Put half of this into a tub of clean
water. Stir thoroughly and while stirring add a pint of liquid glue.

METHODS OF SOIL INOCULATION

183

Now wet the seeds by sprinkling this muddy water over them and
stirring them with a hoe or rake until all are wet. This wetting

FIG. 122. — Effect of inoculation on garden peas. Inoculation alone will often increase the
yield of peas. 1, no inoculation; 2, inoculation. (Wisconsin Station.)

can easily be done with the seeds in a shallow box or on a smooth
floor. Next sift the remainder of the good soil over the seeds and

184 SOIL ORGANISMS IN RELATION TO SOIL FERTILITY

stir until the moisture is taken up by the soil. The seeds are now
ready to be drilled in the field.

Another common way to inoculate is to apply the bacteria to
the seed as pure culture at the time of seeding or planting. Pure
inoculation cultures are bacteria grown in the absence of all other
kinds of bacteria on sterilized foods. These pure cultures may be
sent out to farmers in liquid form, on vegetable jelly, or in steril-
ized soil. Good results are secured through this method of inocu-
lation only when fresh cultures containing the proper organisms
are used. Farmers may secure pure inoculation cultures from the
United States Department of Agriculture, from their State Experi-
ment Station, or from reliable seed houses. Full directions for
using accompany the cultures.

Some recommend the sowing of about a pint of alfalfa seed per
acre in with the usual seeding mixture of- clover and grass as a
means of inoculating the soil for alfalfa. In actual practice this is
not a safe and sure method of inoculation. It is rather a test to
determine whether or not the soil conditions are right for alfalfa.
Moreover, an acid soil is usually lacking in the alfalfa nodule-
bacteria, so that any attempt to grow a few alfalfa plants on such
a soil results in failure, not only because of the lack of the proper
organisms, but also because of the lack of lime. To be sure of
inoculation on non-acid soils it is best to inoculate with soil or
pure culture. On acid soils, the only sure way to succeed, especially
with alfalfa, is to lime the land first, then inoculate.

How Often to Inoculate. — Usually when a soil becomes inocu-
lated and grows a certain legume successfully, further inoculation
for that particular legume is unnecessary, provided the soil con-
ditions remain favorable for the bacteria.

Conditions Favoring Soil Organisms. — As in case of all living
things, the growth and activity of all the helpful soil organisms
are promoted only when favorable conditions surround them.
Aside from food and suitable moisture and temperature conditions,
they particularly require a well-aerated soil, a soil containing a
sufficient amount of organic matter, and most of them require a
soil not sour or acid. These last three conditions are within the
control of the farmer, thus making it possible for him to plan and
direct his farming operations in such a way as to foster these tiny
workers in the soil.

QUESTIONS 185

Illustration Material for Lessons. — Show nodules on the roots of some of
the common legumes.

Demonstrations. — Material Needed. — Five one-gallon crocks; about 12
quarts of loam; about 10 quarts of soil void of alfalfa nodule organisms; a few
corn and grain seeds; 2 grams each of nitrate of soda and sodium acid phos-
phate; a few hundred alfalfa seeds; and alfalfa inoculation soil or culture.

To Study the Effect of too Much Water on Plant Growth in Relation
to Nitrification. — Procedure. — Plant 3 one-gallon crocks of sandy loam, or
loam taken from the field, to corn and small grain. Water them and keep
them under the same favorable growing conditions. To crock No. 1 apply
2 grams each of dissolved sodium nitrate and sodium acid phosphate (to enrich
the soil). When the plants are about 3 to 4 inches high, treat them as follows:

Crock No. 1 — Keep flooded with water.

Crock No. 2 — Keep flooded with water.

Crock No. 3 — Water normally.

Start moisture treatments all at the same time. Continue these treat-
ments for at least 2 weeks, or until results are definite.

Questions. — (a) Why did the plants in crock No. 2 turn yellow so soon?

(6) Explain the results secured in crock No. 1.

(c) Define nitrification.

(d) Name conditions in the field that favor nitrification.

To Demonstrate the Importance of Inoculation. — Procedure. — Fill two
one-gallon crocks with soil free of alfalfa nodule organisms. Provide proper
conditions in each crock for growing ali'alfa. Inoculate one crock, but do not
inoculate the other. Seed both crocks to alfalfa, water, and observe results.

Field Studies. — Observe nodules on the roots of clovers and other legumes.
Do not pull roots but dig them, and rinse off the soil in water.

Examine the roots of "yellow" alfalfa, and of vigorous plants for nodules.

Home Experiment. — It would be of interest as a home experiment to
plant two strips side by side of some legume not commonly grown in the com-
munity. One of the strips should be inoculated, and the other left uninocu-
lated. (Consult text.) Note results in nodule development and in yield.

QUESTIONS

1. Name the different classes of soil organisms. What are microorganisms?

Tell of their number in soils.

2. Into what three classes may the helpful soil organisms be grouped?

3. What becomes of all dead organic material? Of what importance is

this fact?

4. How is it possible that the nitrogen in organic matter becomes available?

5. From what main source does a crop like corn get its nitrogen? Its min-

eral elements?

6. Explain why the fertility of some light-colored soils rich in the mineral

elements may be increased just by plowing under a crop of green rye.

7. Upon what depends the value of an organic fertilizer, like dried blood?

Of some insoluble mineral fertilizer, like rock phosphate?

8. Explain by aid of a diagram how plants are able to secure nitrogen from

the organic matter in soils. What is the meaning of nitrification?

9. What becomes of the nitrates formed as the result of nitrification?

10. What do "catch crops" catch? Why are some crops called "cover" crops?

11. Does the process of nitrification increase the nitrogen content of

soils? Explain.

12. What is meant by denitrification?

13. How may the beneficial effect of manure on peat and muck soils be

partly explained?

186 SOIL ORGANISMS IN RELATION TO SOIL FERTILITY

14. What is meant by nitrogen fixation in soils? How else is nitrogen fix-

ation accomplished?

15. What are the main differences between legumes and non-legumes?

16. From what sources do legumes get their nitrogen?

17. How much nitrogen may be added to the soil by the free nitrogen-

fixing organisms?

18. Tell how the nodule bacteria work.

19. How much nitrogen may be added to the soil on a farm in growing clover?

In growing alfalfa?

20. Explain why, under like conditions, corn should yield better on clover

sod than on timothy.

21. Discuss the relation of crop failure to a lack of nodule bacteria. Why is it

necessary that legumes should have these nodule bacteria?

22. What is the meaning of soil inoculation? Cross inoculation? Illustrate.

23. Suppose a field is to be inoculated for alfalfa; explain how it should be done.

24. If, after growing alfalfa, soybeans are to be grown, would inoculation be

necessary for soybeans? Why?

25. How often should inoculation for the same legume be made?

26. Have you ever seen legumes that probably needed inoculation?

27. What are the soil conditions favorable to the growth and activity of the

helpful soil organisms?

28. For an outline summary of this chapter, see table of contents.

CHAPTER XII

NITROGEN, PHOSPHORUS AND POTASSIUM IN
RELATION TO SOIL FERTILITY

An Important Controllable Factor. — " Sufficient available
plant-food elements'' is a fifth positive factor determining soil
fertility (Chapter VII). The maintenance of fertility may be

FIG. 123. — Feed the soil and you feed the crop. When this peat soil was supplied with the
necessary elements of plant food this splendid crop of corn was the result.

accomplished in a large measure by maintaining in the soil a good
available supply of the important elements (Fig. 123).

Outside the irrigated sections the source of "water" is the rain-
fall; thus, so far as the farmer is concerned, the water problem is
mainly a question of conserving and controlling this moisture for
crop use. As regards " air, " it is free and abundant — and the supply
of carbon dioxide contained in it remains practically the same.
With drainage and good tillage a lack of air in the soil need never
be a cause, either directly or indirectly, of low yields. "Good
tilth" can neither be bought nor sold, leached out of the soil or

187

188

NITROGEN, PHOSPHORUS AND POTASSIUM

added to it. It is a soil condition that good soil management
maintains and poor management destroys. " Helpful soil organ-
isms" perpetuate themselves, and they remain in the soil so long-
as the farmer maintains soil conditions favorable to them. But
as regards the " plant-food elements," a virgin soil may become
depleted, and crops consequently fail. Moreover, some soils are
unproductive because they especially lack some one essential
element (Chapter VI). The only way to restore a depleted supply

FIG. 124. — Sixty-four bushels of potatoes for nine dollars. When a necessary fertilizer
was added to this soil a 64 per cent increase in yield was obtained.

of elements, or to nullify the effect of a lack of any one or two ele-
ments, is to add plant-food material to the land (Fig. 124). It is
entirely possible for the farmer to add fertilizing elements to the
soil, and to maintain in the soil a sufficient available supply, so
that his efforts concerning moisture conservation, aeration,
tillage, etc., shall not be in vain. Compare Figures 125 and 126.

Of the elements essential to plant growth, four are much dis-
cussed in relation to crop production, viz., nitrogen, phosphorus,
potassium, and calcium (lime).1 Since the liming of soils is so

1 Commonly, the word "lime" is used instead of calcium, though it is the
oxide of calcium (CaO).

AN IMPORTANT CONTROLLABLE FACTOR 189

FIG. 125. — Sixty-nine and one-half bushels of oats per acre. Unfertilized. (See Fig. 126.)
Bundles represent growth on one square rod. (Wisconsin Station.)

FIG. 126. — Eighty-seven bushels per acre when fertilized with three hundred pounds of
acid phosphate per acre. (Wisconsin Station.)

important a subject, it will be discussed in a chapter by itself.
In this chapter special consideration will be given nitrogen, phos-
phorus, and potassium.

190 NITROGEN, PHOSPHORUS AND POTASSIUM

Substances Contributing to the Supply of Available Plant-
food Elements. — When the pioneer farmer tilled the virgin soil, he
reaped bountiful harvests of corn and grain — not for one year only,
but for many years. What contributed to the crop needs of
nitrogen and mineral elements? Three substances, viz.:

(a) A small amount of soluble salts in the soil.

(b) Organic matter.

(c) Mineral soil particles.

As time went on, crop yields fell off, and the farmer began to
realize that soils can become " exhausted" or "worn out." From
times immemorial tillers of the soil have been advised to keep up
the "strength" of the land by adding substances to it. Herein
lies the theory of fertilizers. The process of adding fertilizing
elements to the soil or rendering available the elements present
in the soil is fertilization. The substances commonly used to add
fertilizing elements to the soil, or to render available those already
there are:

(a) Vegetation and crop residue, as roots, stubble, straw, etc.

(6) Green crops plowed under (green manuring).

(c) Commercial fertilizers.

(d) Manure.

Vegetation produced the organic matter found in virgin soils.
Its value is well known. All plant residue such as roots, stubble,
etc., aids materially in maintaining the organic matter. Thus leaf
mold, grass, etc., should always be plowed under wherever possible,
and not burned.

The further discussion in this chapter will be under three main
headings: (1) Green Manuring; (2) Commercial Fertilizers, and
(3) Manures.

GREEN MANURING

Green Manuring and Its Benefits. — Green manuring is the
plowing under of green crops for soil improvement. The benefits
to be derived through this practice are : The organic matter may be
maintained; nitrogen is added to soils, in case of legumes; the
available supply of nitrogen and mineral elements is increased;
soil structure is improved ; the development of good tilth through
tillage is made easier; and soils become less difficult to
work. Some green manuring crops may also serve as catch
and cover crops.

Legumes are the best crops to use whenever possible. In

AN OLD PRACTICE

191

southern California it was found that it required from 270 to 1080
pounds of nitrate of soda2 together with a green manuring crop of
barley to produce as good a yield of corn as when a legume was
plowed under. In either case the same amount of organic matter
was added.

In a test made in Canada, increases of twenty-eight per cent
in potatoes and forty per cent in corn resulted in growing these
crops following clover.

In Alabama the plowing under
of a legume (cowpeas) gave a clear
gain of 696 pounds of seed cotton
per acre (Fig. 127).

A legume crop (crimson clover)
plowed under in Maryland gave an
increase of twenty-seven bushels in
potatoes and seven bushels in corn
(Fig. 128).

At the Virginia Truck Station,
Norfolk, " cowpeas plowed under
green in the fall gave as large a
yield of cabbage per acre as twenty
tons of stable manure."

On the better soils where good
clover or alfalfa can be grown
often, the need of a special green
manuring crop is seldom felt.

It is Necessary to Maintain
Organic Matter. — Many farmers
fail to appreciate the necessity of
replenishing the organic matter in
soils, and too often clover is left out of the cropping plans.
On many farms clover does not grow so well as it used to, or fails
entirely. This should be taken as a warning that something is
wrong with the soil or the system of farming. When clover is
left out of the cropping system, and the organic matter of the soil
is allowed to become depleted, it is only a question of a few years
when the other crops will cease to give paying returns.

An Old Practice. — Green manuring to add organic matter and
nitrogen is not a new farm practice. Its value has long been known.
Twenty centuries ago Varro told the Roman farmers the following:

2 A soluble nitrogen fertilizer.

Fio. 127.— Cowpea. (U. 8. D. A.)

192

NITROGEN, PHOSPHORUS AND POTASSIUM

"Certain things are to be sown, not with the hope of any
immediate profit being derived from them, but with a view to the
following year, because being plowed in and left in the ground,
they render the soil afterwards more fruitful."

Crops for Green Manuring. — Many crops may be used for
plowing under: legumes, rye, buckwheat, rape, oats, etc. The

Fia. 128.— A, Hairy vetch. B, Crimson clover. (U. S. D. A.)

clovers and vetch (Fig. 128) can be seeded one year with grain
and turned under in the fall or in late spring. Alsike clover is suit-
able for low lands. Mammoth clover is well adapted for poor soils
to get rank growth.

Cowpeas, soybeans (Fig. 129), rape, and crimson clover3 may
be sown in between the rows when a cultivated crop is "laid by."4

3 Crimson clover is commonly grown as a green manuring and forage crop
along the Atlantic seaboard from New Jersey to the Gulf States.

4 "Laid by" means last cultivation.

PLOWING UNDER THE CROP

193

When the crop is harvested, the cowpeas, clover, etc., serve as
catch crops, and are plowed under later in the fall. Cowpeas,
soybeans, common vetch, field peas, and velvet beans are the
legumes best adapted to single summer growth. Sweet clover is
a biennial (Fig. 130).

Green manure is much needed in the
South. There each year the season is long
enough to permit the growing of one or
two crops for sale and at least one crop for
plowing under. For this reason soybeans,
cowpeas and velvet beans are used more
than any other crop.

Fia. 129.— Soy beans.
(U. S. D. A.)

Fia. 130. — Sweet clover.
(U. S. D. A.)

Plowing Under the Crop. — Generally, the best time to plow
under a legume crop is when it is still green. Rye, or any other
grain crop, should be turned under before it becomes too strawy.

Sometimes when a heavy growth is plowed under at the begin-
ning of a prolonged dry period, injury results, because of the drying
out of the seed bed. In such cases, good contact should be created,
if possible, between the seed bed and the subsoil. In this, good
plowing is advantageous (Figs. 75 and 76). .
13

194

NITROGEN, PHOSPHORUS AND POTASSIUM

It is always best to turn the green crop immediately under.
In this work jointers and coulters are useful (Fig. 74). A chain
may also aid in getting the growth turned under the furrow slice
(Fig. 131). Sometimes disking before plowing is helpful.

Green Manures for Cultivated Crops. — It is a general practice
to follow green manures with cultivated crops such as corn, cotton,

FIQ. 131. — Turning under weeds with the aid of a chain.

cane, tobacco, potatoes, etc. Cultivation favors the decomposi-
tion of the green crop, thereby rendering available more plant-
food elements.

Green Manuring Necessary in Soil Improvement. — In practi-
cally all soil improvement plans, green manuring occupies an
important place. In some cases the growing and plowing under of
a crop of buckwheat proves the best method in making possible
the regeneration of very poor or exhausted soils. Many sands are
so poor that rye is the only possible first crop. When the rye crop
is plowed under, it makes possible the growing of other green ma-
nuring crops, as soybeans, cowpeas, or mammoth clover, which,

SOME HINTS ON GREEN MANURING 195

together with lime and certain fertilizers, make productive sands
a reality.

The improvement of the lighter colored and long-cropped
soils is dependent upon the addition of organic matter and nitrogen.
This becomes a primary object, and whatever other soil treat-
ments are necessary, they are made not only to produce the organic
matter, but at the same time to benefit all other crops.

In Australia many soils are so poor that they are incapable
of producing a paying crop; but when cowpeas are grown and
plowed under, these soils can be regenerated.

Feeding vs. Plowing Under Crops. — The question often arises,
"Is it not better to feed the crop than to plow it under?"
This is to be determined by the good judgment of the farmer. If
the soil is a black loam, or a black silt loam, and is in a good state
of fertility, feeding the crop and returning the manure, no doubt,
is the better practice. On the other hand, if the addition of organic
matter and nitrogen is the key to the improvement of any soil,
then plowing under the crop would be the better plan. In this
respect the advice given by Varro is still good today.

In many cases when a farmer has sufficient hay and a good
second growth (rowen) comes on, this second growth may better
be turned under than be cut for hay or allowed to go to seed.

Some Hints on Green Manuring. — In the regeneration of
very poor soils, it is necessary to plow under the year's crop to
make improvement possible. In such cases the crop is sacrificed
for the good of the land. Under good soil management, it is not
necessary to lose a crop in order to be able to grow green manure.

When two grain crops are grown in succession, the first crop
may be seeded to mammoth clover which is plowed under in the
fall. The second grain crop is then seeded with medium, alsike,
or crimson clover for hay or pasture to follow the grain.

In potato sections, rye may be scattered over the field at harvest
time, the digging covers the seed, and the growth is plowed under
in the spring, previous to planting. Or the rye may be seeded to
clover, the rye cut as a cash crop, and the clover plowed under
for the potato crop the following year.

A green manuring crop may be planted in between the rows of
a cultivated crop at the last cultivation, and plowed under in
the fall.

Sometimes a rank growth of weeds may prove very effective
as a green manuring crop.

196

NITROGEN, PHOSPHORUS AND POTASSIUM

COMMERCIAL FERTILIZERS

Commercial fertilizers are manufactured preparations used to
add plant-food elements to the soil, particularly nitrogen, phos-
phorus and potassium. These elements in fertilizers are commonly
expressed as " nitrogen (N)," ''phosphoric acid (P20s)," and
"potash (K2O)," respectively. Nitrogen (N) is sometimes
expressed as "ammonia (NH3)." To avoid any misconceptions,
the names of the elements are retained in this discussion.

Some substances, as common salt, for example, are called soil
stimulants, or indirect fertilizers, because they do not contain any
nitrogen, phosphorus or potassium, but cause changes in the soil
liberating the plant-food elements already there.

Four Classes of Commercial Fertilizers. — Commercial fertil-
izers may be grouped into four classes, viz.: (a) Nitrogen
fertilizers; (6) phosphorus or phosphate fertilizers; (c) potassium
or potash fertilizers, and (d) mixed fertilizers.

Nitrogen Fertilizers. — The common nitrogen fertilizers are:

Common names

Per cent
nitrogen

Availability

(a) Nitrate of soda, or sodium nitrate.
(b) Ammonium sulfate, or sulfate of
ammonia

15

20

Very readily available.
Readily available.

(c) Dried blood, or blood meal
(d) Cottonseed meal

6-15
4-8

Becomes quickly available.
Nearly equal todried blood.

Other nitrogen fertilizers are : Dried meat scraps, tankage, dried ground fish scrap,
hoof meal, guanos, wool waste, peat, calcium cyanamid, calcium nitrate, and others.

Nitrate of Soda. — The best known and most widely used
nitrogen fertilizer is nitrate of soda. This is a salt obtained from
natural deposits found particularly in northern Chili. The origin
of this large deposit is not definitely known.

Nitrate of soda can be utilized directly by plants without first
undergoing decomposition changes. Because of its solubility and
the ease with which it is leached from the soil, the amount applied
to the acre at any one time is not very large. The usual application
is from 100 to 400 pounds applied in frequent small amounts during
the early growing period. It is often used in small quantities to
force plant growth, as on tobacco beds. Market gardeners and
truck growers use this fertilizer more than do general farmers,
and it is used more extensivelyin theEastern states than in the West.

Ammonium Sulfate. — Sulfate of ammonia is a salt made as

PHOSPHATE FERTILIZERS

197

a by-product in the manufacture of coke and illuminating gas.
In the soil this fertilizer undergoes decomposition and nitrification.
It has been found that corn, peas and rice can use nitrogen directly
from this salt. This fertilizer has about nine-tenths the efficiency
of nitrate of soda, and it may be used in a similar manner. The use
of ammonium sulfate will no doubt become more general than
formerly, since the nitrate deposits are destined to exhaustion in
a few generations.

Dried blood is the evaporated, dried and finely ground blood
of slaughtered animals. This is one of the best organic nitrogen
fertilizers. Under proper soil conditions it proves about ninety
per cent as efficient as nitrate of soda.

Cottonseed meal is a product formed when oil is removed
from cotton seed. The extracted residue is ground fine. It is
extensively used as a fertilizer in the South.

This material, as well as all other available nitrogen-containing
substances, are much used in the manufacture of mixed fertilizers.

Legumes to Solve Nitrogen Problem. — The demand of all
crops for nitrogen is greater than for the other elements. (See
Table of Crop Requirements, Chapter VI). This, together with
the fact that the conditions of life in the civilized quarters of the
globe are such as to cause a constant loss of nitrogen, has caused
the question of the available nitrogen supply of the world to be
looked upon as lying at the very foundation of agriculture, and
to demand most careful consideration. One of the greatest prob-
lems in the maintenance of soil fertility is how to secure and keep
a sufficient supply of available nitrogen at the least cost. This is
too large a problem to be solved through the use of commercial
nitrogen fertilizers alone. It is now generally agreed that legumes
must play the larger part in the solution of the nitrogen problem.
Moreover, it should be remembered that fertilizers can never
become a substitute for the organic matter so essential in all soils.

Phosphate Fertilizers. — The common phosphate fertilizers are:

Common names

Per cent
phosphorus (P)

Per cent
phosphoric
acid (PaOs)

Availability of phos-
phorus-containing
ingredient

a) Rock phosphate '. . .
6) Basic slag, or Thomas slag
c) Ground steamed bone
meal*

11.8 to 13.5
4.5 to 8

10 to 11

= 27 to 31
= 10 to 18

= 23 to 25

Insoluble.
Less than bone meal.

Medium.

(d) Acid phosphate

5.7 to 8

= 13 to 18

Readily available.

* Ground steamed bone meal also contains 2 to 3 per cent nitrogen.

198 NITROGEN, PHOSPHORUS AND POTASSIUM

Expressing Equivalents. — The fertilizing constituent of phos-
phate fertilizers may be expressed in three ways: as "phosphorus
(P)," as " phosphoric acid (P2O5)," and as "bone phosphate of lime
(BPL)." The per cent of "phosphoric acid" is always higher
than the per cent indicating the phosphorus content of a fertilizer;
and the per cent expressing the equivalent of bone phosphate of
lime is higher still ; to illustrate, thirteen per cent phosphorus (P)
equals thirty per cent phosphoric acid (P2O5) equals sixty-five
per cent bone phosphate of lime»(BPL).

Phosphoric acid (P2Oo) and bone phosphate of lime (BPL)
may be reduced to the common elemental name as follows :

Per cent or pounds phosphoric acid X 0.436 = per cent or pounds of phos-
phorus, respectively. Per cent or pounds of bone phosphate of lime X 0.2 =
per cent or pounds of phosphorus, respectively.

Rock Phosphate. — Rock phosphate is finely pulverized phos-
phate rock. The main sources of this fertilizing material' in the
United States are deposits in Tennessee, South Carolina, Florida,
Arkansas, Kentucky, Utah, Wyoming, Montana and Idaho.
Because of its insolubility, this fertilizer gives best results on
most soils when it is mixed with manure or plowed under with
a green manuring crop. On some muck and peat lands it has given
very good results when applied directly to the soil and thoroughly
mixed with it, at the rate of about 800 pounds per acre. In soil
improvement plans, especially when the phosphorus supply is to
be increased and maintained, it has been found good practice to
mix rock phosphate with stall manure by sprinkling it in the
gutters in the barn during winter feeding, at the rate of from fifty
to one hundred pounds to the ton of manure produced. This is
equivalent to approximately two to four quarts to the cow daily.
Rock phosphate may also be dusted over the manure when loaded
on spreaders.

Basic slag, or Thomas slag meal, is pulverized slag of Bessemer
steel converters. The phosphorus is withdrawn from the molten
phosphorus-containing iron. This fertilizer is much used in Euro-
pean countries and to a certain extent in eastern United States —
it being imported from Europe. The phosphorus-containing iron-
ore in Alabama, which is being converted into steel, may prove
a valuable source of this fertilizer.

Ground Steamed Bone Meal. — This fertilizer is pulverized
steamed bone. The bones from meat-packing plants are steamed,
or otherwise treated, to remove the fat- and sometimes the gelatine

AVAILABLE PHOSPHATE 199

also. After the extraction, the bones crumble readily and are
easily ground. Bone meal is a much-used fertilizer, especially by
truck gardeners. About 100 to 300 pounds and more may be
applied per acre.

Acid Phosphate. — Acid phosphate is made by treating an
insoluble phosphate with an acid and thereby changing it into a
soluble phosphate. This is the most easily soluble phosphate
fertilizer. The name " superphosphate " is sometimes applied to
it. The manufacturing process consists mainly in treating rock
phosphate with sulphuric acid. Because of its availability, or
solubility, acid phosphate is very generally used, especially when
immediate results are desired. Applications may vary from 100
to 500 pounds per acre.

Many Soils Need Phosphates. — Many soils are particularly
deficient in phosphorus, either because they never contained any
appreciable supply, or because of exhaustive cropping. Phos-
phorus deficiency is especially prevalent in sections where, during
the early days, wheat was the one crop raised. So far as the soil
is concerned, that was a period of most wasteful farming.5 Noth-
ing was returned to the land, the grain and other products were
sold, and the straw was burned. The organic matter was rapidly
used up and the phosphorus was carried away with the wheat. The
only way to correct this phosphorus deficiency and to maintain a
sufficient supply in the soil is to buy phosphorus and add it to the
land. Phosphorus may be purchased in the form of fertilizers and,
to a lesser extent, in the form of feeds, such as bran, for example.
The feeds when fed enrich the manure produced.

It is common experience to obtain crop increases of from ten
to fifty per cent and more by using phosphate fertilizers. The
important effects produced by supplying sufficient phosphorus are :
(a) The grain fills better and consequently weighs more per unit
volume; (6) plants develop strong and extensive roots, and (c)
crops often mature earlier.

In general, the following soils are benefited by phosphate
fertilizers : Soils exhaustively cropped, peat and muck soils, sands,
and black, acid loams, and silt loams.

Available Phosphate More Important Than Total.— The
amount of phosphorus that crops can secure is of more importance

5 The pioneer wheat-farmer can hardly be blamed for his system of farm-
ing. The fact that the soils were rich enough to grow good crops of wheat
made possible the construction of roads, the building of cities, and general
developments which are enjoyed today.

200

NITROGEN, PHOSPHORUS AND POTASSIUM

1!
ii

THE CHOICE OF PHOSPHATES

201

than the " total" amount contained in soils. Some soils may con-
tain a very good supply but still respond to phosphate fertilization.
Other soils containing lower amounts may give no indication of
phosphorus deficiencies. When a silt loam, for example, has had
its original phosphorus supply reduced one- third to one-half, and
is in need of phosphates, it is not necessary to add an amount of
fertilizer to raise the phosphorus content to the original amount,
but to fertilize sufficiently to enable the soil to furnish the phos-
phorus demanded by profitable crops.

FIG. 133. — What happened when the fertilizer missed. This particular peat soil responds
best to a mixture (1 to 1) of muriate of potash and acid phosphate.

The Choice of Phosphates. — When immediate results are
desired and when top-dressings are to be made, a soluble fertilizer
should be used. Acid phosphates, or superphosphates, are, there-
fore, especially adapted to all cases where spring top-dressing is
practiced; as, for example, on grass land, for clover, alfalfa, and
winter grains.

Bone meal gives excellent results on soils that are open and
inclined to be sandy or gravelly.

Rock phosphate has given good results on peat and muck soils
and on upland soils exceptionally rich in decomposable organic
matter. Compare Figures 132 and 133.

202

NITROGEN, PHOSPHORUS AND POTASSIUM

Basic slag, bone meal and rock phosphate are good fertilizers
to use for crops like corn, grain, and potatoes, when grown on acid
soils. Basic slag acts well on clayey soils.

For plants and soils which need liming, phosphates give more
economical returns when lime is added to the land. This is particu-
larly true in case of acid phosphates.

Rock Phosphate vs. Acid Phosphate. — The comparative fertil-
izing values of rock phosphate and acid phosphate have been much
discussed. Most available data seem to indicate that, in general,
acid phosphate is the more profitable.6 On some of the black
prairie soils of the Middle West, certain results have shown that
rock phosphate is to be compared favorably with acid phosphate.

Potash Fertilizers. — The common potash fertilizers are:

Common names

Per cent
potassium (K)

Per cent
"potash"
(K20)

Availability

(a) Muriate of potash, or potas-
sium chloride

41.5 to 44

50 to 52

Soluble.

(6) Sulfate of potash, or potas-
sium sulf ate
(c) Kainit

40 to 42
10 to 12

48 to 51
12 to 14.5

Soluble.
Soluble.

(d) Wood ashes

2 to 10

2.5 to 12

Potash soluble.

The fertilizing constituent of potash fertilizer may be expressed
either as the element potassium (K), or as the oxide of the element
" potash" (K2O). To reduce " potash" to the element equivalent,
multiply the number of per cent or pounds of " potash" by 0.83.

Sources of Potash. — The main source of potash fertilizers is
crude salts mined near Strassfurt, and in Alsace. No other deposits
of potassium salts are so extensive as these. It has been estimated
that the Strassfurt mines alone are capable of supplying the world
with potash for thousands of years.

There are several sources of potassium in the United States,
among which are : Dried-up salt lakes, sea weed, wood ashes, potas-
sium-containing rock minerals, and as a by-product in cement
manufacture. The potassium salts obtained from these sources
have thus far been used in making mixed fertilizers. Tobacco
stems used as potash fertilizer are shown in Figure 134.

Muriate of Potash. — Muriate of potash is a prepared product
derived from crude potash salts. This is the most common of the
potash fertilizers. It is all soluble in water.

6 This conclusion is based on prices paid for fertilizers before the World War.

USE OF POTASH FERTILIZERS

203

Sulfate of Potash. — This is another product derived from crude
potash salts. It is not so generally used as the muriate. This
fertilizer is likewise all soluble in water.

Kainit is a crude potash salt, unprepared except by grind-
ing. It is water soluble, and is used mainly in the making of
mixed fertilizers.

Wood ashes vary in the amount of potassium they contain.
Thoroughly leached ashes are of little or no value as a potash fertil-
izer. Hardwood ashes are generally richer in potassium than those
of soft woods. Woods burned at high heat produce ashes much
lower in potassium than when burned at low heat, as in a kitchen

FIG. 134. — Tobacco stems are a good potash fertilizer.

range. In addition to potash, wood ashes contain from fifty to
seventy per cent carbonates of lime and magnesia.

Use of Potash Fertilizers. — Peat, muck and sands are soils
particularly in need of potash fertilizers. Though the heavier
soils contain an abundant supply of potassium, yet some of them
respond to potash treatment. Crops demanding an abundant
supply of potassium are: Sugar beets, clovers, alfalfa, cabbage,
tobacco, turnips and corn (Figs. 135 and 136).

For most soils needing potassium, muriate of potash is suitable
and the cheapest. From 100 to 200 pounds to the acre per year,
applied broadcast, is the usual application of either the muriate
or sulfate for corn, turnips, potatoes and clover; and from 200 to
300 pounds for onions, cabbage and sugar beets.

Certain results seem to indicate that sulfate of potash produces
a better quality of potatoes and tobacco than the muriate. Other
results show that when soil conditions are right as regards car-

204

NITROGEN, PHOSPHORUS AND POTASSIUM

bonate of lime and moisture, the muriate may give as good results
as the sulfate.

Kainit is much used in the South.

FIG. 135.

FIG. 135. — For corn (in a pot test) this peat soil responded to phosphate treatment.
O, no treatment; N, nitrogen fertilizer; P, phosphate treatment; K, potash; PK,

phosphate and potash. (See Figure 136.)

FIG. 136. — For cabbage, potash fertilizer gave the greatest response. Same soil as in
Figure 135. A, response to phosphate; B, response to potash.

Wood ashes are excellent for acid, peat soils. From one to two
tons per acre is a common application.7 No mixture of commercial
fertilizers gives the results on acid marsh soils as do ashes.

7 When containing 30 to 40 per cent moisture.

COMMERCIAL FERTILIZERS IN GENERAL

205

Mixed Fertilizers. — Commercial fertilizers containing nitrogen,
phosphorus and potassium are called mixed fertilizers. Those
containing all three of the fertilizing elements are called " com-
plete" fertilizers. In this respect, manure is to be regarded as a
complete fertilizer.

Hundreds of brands of mixed commercial fertilizers are to be
found on the market — sold under various trade names; such as,
Corn and Cotton Grower, Dreadnaught Fertilizer, Prolific Crop
Producer, etc. These fertilizers are commonly spoken of in terms
of the per cents of the fertilizing constituents contained in them;
for example, a mixed fertilizer containing two per cent nitrogen
(N), twelve per cent phosphoric acid (P205) and two per cent
potash (K2O) is called a "2-12-2" fertilizer.8 A "0-12-4" fertil-
izer means one containing no nitrogen (N), twelve per cent
phosphoric acid (P2O5) and four per cent potash (K2O).

The following shows the meaning of some mixed fertilizers
in terms of the elements:

Per cent

Per cent

Per cent

Per cent

Per cent

P.er cent

nitrogen

(N)

phosphoric
acid (P206)

potash.
(K20)

nitrogen
(N)

phosphorus
(P)

potassium
(K)

4

8

4

4

3.5

3.3

2

12

2

2

5.2

1.7

0

10

8

0

4.4

6.6

Use of Mixed Fertilizers.— Mixed fertilizers are very generally
used. Applications vary from 50 to 1500 pounds and more to the
acre. It is better to purchase these fertilizers on the basis of what
they contain rather than because of their names.

Commercial Fertilizers in General. — Many erroneous ideas
are prevalent regarding the use of commercial fertilizers, especially
in sections where fertilizers are little used or practically unknown.
Some believe they injure the soil, and that when once used their
use must be continued. It is not because the "soil gets a bad
habit" that many farmers continue the use of fertilizeps, but be-
cause of profitable returns. Fertilizers sometimes fail for the
following reasons: The wrong kind of fertilizer may have been
used; it may have been applied in the wrong manner; the soil
may lack proper underdrainage, and there may have been a
deficiency of moisture.

8 In some Southern states phosphoric acid is usually mentioned first, then
nitrogen and potash. A "10-4-3" fertilizer in those states means, therefore,
10 per cent phosphoric acid, 4 per cent nitrogen and 3 per cent potash.

206

NITROGEN, PHOSPHORUS AND POTASSIUA1

No farmer, however successful, should ever think of trying to
maintain the fertility of his soil through the use of commercial
fertilizers alone. Legumes, grass, green manuring crops and barn-

FIG. 137. — Four rows without fertilizer in the drill. To the lett and right 125 pounds
of a 1-8-1 mixed fertilizer were applied per acre in the drill with a fertilizer attachment
on the planter. (See Fig. 138.)

FIG. 138. — An eighty-one per cent increase in silage corn at harvest time. To left, unfer-
tilized, 8.7 tons per acre; to right, fertilized, 15.8 tons per acre. A long-cropped soil.

yard manure are indispensable. Except for truck crops and pota-
toes, it is wise economy to use commercial fertilizers in a definite
plan of more permanent soil improvement and fertility mainte-
nance rather than to make light applications mainly to stimulate

PROFITS DETERMINE USE OF FERTILIZERS 207

the one crop to which it is applied. Though it may be good business
practice to apply fertilizers to a crop and increase the net profits,
yet it is still better practice to accomplish this in such a way as to
effect a more permanent improvement of the soil, which will serve
to benefit several crops in succeeding seasons.

Profits Determine Use of Fertilizers. — The use of commercial
fertilizers depends mainly upon whether or not the value of the
increased yields more than offset the cost of the application (Figs.
137 and 138). On many soils the use of commercial fertilizers
does not pay (Fig. 139). The best returns from fertilizers are

FIG. 139. — Corn stimulated by complete fertilizer applied in the hill (125 pounds per
acre). No appreciable difference in yield at harvest time. Soil in good state of fertility.
(See page 208.)

obtained when soils are sufficiently supplied with moisture and
organic matter (compare Figs. 140 and 141).

The cost of fertilizers varies in different sections, depending
largely upon the distance from distributing centers. Fertilizers
are usually purchased on the unit basis. One per cent of a ton,
or twenty pounds, is called a unit. Normal prices for nitrogen
have been about three dollars per unit; phosphoric acid (P2O5)
from twenty to forty-five cents in rock phosphate, and about one
dollar in soluble phosphates; and potash about one dollar to
one dollar and forty cents per unit.

The World War had a decided effect on fertilizer prices. The
price paid for nitrogen was six to seven dollars per unit; soluble

208

NITROGEN, PHOSPHORUS AND POTASSIUM

phosphoric acid about two dollars, and " potash" seven dollars
and more per unit.

FIG. 140. — Corn responded during early growth to about 100 pounds of a mixed fertilizer
(1-8-1) applied in the drill. (See Fig. 141.)

FIG. 141. — No appreciable difference in the yield at harvest time, because the land was
well manured. Same field as shown in Figure 140.

Soils and Crops Determine Kind of Fertilizer to Use. — The
soil supply of the available plant-food elements and the kind of

SOILS AND CROPS DETERMINE KIND OF FERTILIZER 209

crop to be grown are two factors determining largely the kind of
fertilizer to use (Figs. 135 and 136). The growing of sugar beets
on peat, for example, requires liberal applications of a potash
fertilizer. The forcing of lettuce and other garden crops requires
an abundant supply of available nitrogen (Fig. 142). The appli-
cation of soluble phosphate fertilizer on many soils proves the
most profitable fertilizer treatment, especially on long-cropped
prairie soils. The improvement of poor soils generally requires
the addition of all the fertilizing elements.

FIG. 142. — Making a second application of fertilizer to head lettuce. The fertilizer is
scattered along the rows and stirred in. (N. Y.)

Mixed or complete fertilizers in comparison with single fertil-
izers commonly give the highest average increases and profits.
This is particularly true in case of wheat, potatoes and cotton.
Frequently a mixture of phosphate and potash gives best results.
Many experiments have shown that the full effect of one fertilizing
element is obtained only when it is associated with the other two.
Moreover, the addition of phosphorus and potassium usually
increases the need of nitrogen for bigger crops. In other tests a
fertilizer, either single or complete, used in conjunction with a
green-manuring crop is the best means to obtain higher crop yields.
14

210 NITROGEN, PHOSPHORUS AND POTASSIUM

These results show that the plant, as well as the animal, requires a
"balanced ration" to enable it to use its food materials most
economically. This emphasizes the necessity of keeping a balanced
condition in the soil in regards to the fertilizing elements.

No general rule can be given for fertilizing soils, since condi-
tions are so variable and soils differ so widely in their characteris-
tics. A certain fertilizer may prove a "best fertilizer" for one soil,
while on another it may be of no value whatever. The only sure
way of determining the fertilizer needs of a crop on any particular
soil is by actual field tests. How the fertilizer needs of soils and
crops may be determined is discussed fully.

High Grade Fertilizers More Economical. — High grade fertil-
izers are usually considered as those containing a relatively large
amount of plant-food elements. Another distinction is: High
grade fertilizers are made of high grade, standard materials like
nitrate of soda, ground bone, acid phosphate, muriate and sulfate
of potash. The low grade preparations, on the other hand,
are usually made by mixing cheaper, inferior and less soluble
materials, like low grade tankage, wood ashes, kainit, peat, etc.
When the amount and quality of the fertilizing ingredients,
freight, and cost of handling are considered, the high grades are
the cheaper.

Home Mixing of Fertilizers. — By home mixing is meant the
mixing of purchased fertilizing materials on the farm. This is
commonly recommended, because the cost per pound of plant-food
elements is lowered, mixtures can be varied to suit particular
soils and crops, and better knowledge is obtained concerning kinds
and quality of different materials carrying fertilizing elements.

The mixing operation is simple. A clean floor, one or two
shovels, a pair of scales, and a sand sieve having about four meshes
to the linear inch is all the apparatus needed. The materials are
first weighed out and placed in a pile on the floor — the bulkiest
material at the bottom. All lumps are broken with the shovel.
The pile is then shoveled over about three times, and the mixture
passed through the sieve. Lumps are broken and added to the
mixture, which is again shoveled over, if necessary, until thor-
oughly mixed:

Home Mixing Rules. — The following rules may be helpful in
home mixing:

(a) Determine the number of pounds of each fertilizing element
contained in one ton or any other araount,of theproposedmixture.

HOW FERTILIZERS ARE APPLIED 211

(6) Determine the number of pounds of the materials required
to furnish these amounts of plant-food element.

(c) Add the amounts of the materials required to make the
mixture, and, if the sum is less than 2000 pounds, or less than the
required amount, add enough fine, dry muck, or any other inert
material (filler) to make a ton, or the required amount of
the mixture.

An illustration: Out of nitrate of soda (fifteen per cent N),
acid phosphate (seven per cent P) and muriate of potash (forty-
two per cent K) a complete 3-10-3 fertilizer is to be compounded,
or one containing three per cent nitrogen, 4.4 per cent phosphorus
and 2.5 per cent potassium.

(a) One ton of the proposed fertilizer contains sixty pounds of
nitrogen, eighty-eight pounds of phosphorus and fifty pounds
of potassium.

(6) Amounts of materials required per ton are: 400 pounds of
nitrate of soda, 1260 pounds of acid phosphate, and 120 pounds of
muriate of potash.

(c) The total amount of materials required is 1780 pounds;
220 pounds of filler are required to make the mixture equivalent
to a ton.

Materials Unsuitable for Mixing Together. — Some mixtures
are to be avoided. These are shown here.

Lime ]

Wood ashes f should not be mixed with

Basic slag j

Acid phosphate

pnospri
lived b(

Dissolved bone
Sulfate of ammonia
Tankage, blood meal, etc.
Manure

How Fertilizers are Applied. — Fertilizers may be applied
broadcast, in the hill or drill, in the bottom of furrows, beside the
rows after the plants are well above ground, and mixed with
manure. In orchards and for crops whose roots are broadly dis-
tributed, the greatest part of the fertilizer, at least, should be
applied broadcast before the crop is planted or before harrowing.
When applied broadcast a much heavier application is usually
made than when applications are made in other ways. About
100 to 300 pounds are common applications for grain; 200 to 500
pounds for grass and corn; 500 to 1000 pounds for orchards; 300
to 1200 pounds for root crops and tubers; and 500 to 1200 pounds
for vegetables and truck crops. The fertilizers applied in the hill
or drill, and those used when heavy applications are made, are
generally mixed or complete fertilizers.

212

NITROGEN, PHOSPHORUS AND POTASSIUM

When much fertilizer is applied, fertilizer distributors are used.
All good makes of grain drills have fertilizer attachments for
distributing fertilizer broadcast at the time of sowing.

When fertilizers are intended to promote rapid growth or to
give the young plants a quick start, they are applied in the hill or
drill. This is usually done through the use of fertilizer attach-
ments on the planters (Fig. 143). Usually 100 to 200 pounds are
applied to the acre in this manner. In case of cotton, 400 and 500

FIG. 143. — A fertilizer attachment on the corn planter. Note the fertilizer spreader (S).

pounds are common applications. In Maine as much as 2000
pounds per acre is sometimes applied in the row at the time of
planting potatoes.

When fertilizers are applied in the hill or drill, special care
should be taken that the fertilizer is not dropped on the seed.
All good fertilizer attachments can be regulated so that soil will
fall in between the fertilizer and the seed, or the fertilizer distrib-
uted along the sides of the row and not on the seed (Fig.
143). When fertilizer is applied in the bottom of a furrow it
should be mixed thoroughly with the soil before the seeds
are planted.

The higher the grade of fertilizer the greater must be the pre-
caution in applying it in the hill, drill or furrow.

SOME FACTS ABOUT MANURE 213

In some cases the greater portion of the fertilizer is applied
broadcast, and a little is dropped in the hill or drill to promote
quick growth. Because nitrate fertilizers are easily leached away,
they are commonly applied beside the rows after the plants are
well up (Fig. 142). This method of application is also
used at times whenever fertilizers are not at hand to be ap-
plied otherwise.

Lasting Effect of Commercial Fertilizers. — In all liberal fertil-
ization a residual or after-effect is secured on the crops following —
often extending through three and four years or more. Results
from broadcast distribution are the most favorable. Often the
growth and ripening of grain is very uneven when it follows a
cultivated crop fertilized in the drill or hill.

In this connection it is of interest to mention the absorptive
power of soils for the fertilizing elements. Nitrogen in the form of
nitrates is easily leached out of the soil. Nitrogen in the form of
ammonia (NHs) in ammonium compounds, such as sulfate of
ammonia, is usually readily absorbed by soils in such a way that it
is less subject than nitrates to immediate losses by leaching. As
regards phosphorus and potassium, these elements are readily
absorbed and retained by soils, the heavier types having greater
absorptive power than sandy soils. Practically all the phosphorus
and potassium, therefore, added in commercial fertilizers, and which
is not used by the crop fertilized, increases the soil supply, and is
drawn upon by succeeding crops.

BARNYARD MANURE AS A FERTILIZER

Barnyard manure, farm manure, or stall manure generally
means the waste materials from the care of livestock. In some
sections it is the only, or the most important, fertilizer used. The
best results with manure, as with any fertilizer, depend upon how
intelligently it is used. There are many facts to be learned about
manure. In the following few paragraphs are mentioned some
important facts about it, and after that are discussed some practical
pointers concerning its care and use.

Some Facts About Manure. — A ton of average, mixed yard
manure contains approximately ten pounds of nitrogen, two pounds
of phosphorus and eight pounds of potassium. When nitrogen is
valued at fifteen cents a pound, phosphorus at ten cents and potas-
sium at eight cents, one ton of such manure has an intrinsic

214

NITROGEN, PHOSPHORUS AND POTASSIUM

fertilizing value of $2.34. When fertilizer prices were greatly
advanced by the World War, a ton of ordinary manure had a value
of about eight or nine dollars.

The value based on the returns from a ton of barnyard manure
under average, general farming conditions is usually higher than
this — depending on the soil, method of cultivation and crops grown.
The returns per ton of yard manure on poor soil amounted to
$4.69 in a five-year test made at the Ohio Station. Corn, oats,
wheat, clover and timothy were the crops grown. Eight tons of
manure were applied to the acre — four to the corn and four to the
wheat. On some farms manure is regarded more as a waste product
only to be gotten rid of (Fig. 144). Usually, however, it is given
a value of from one dollar to one dollar and a half a ton. On most
dairy farms the value of the manure produced much more than
offsets the labor cost of feeding and caring for the herd (milking
not included). The annual total labor cost per cow is figured at
sixteen to twenty-three dollars, and the value of manure produced
at twelve to seventeen dollars. (Manure at about a dollar and a
half per ton.)

Manures Differ in Fertilizing Value. — The accompanying table
shows the composition of fresh manure produced by various
farm animals.

Composition of Fresh Manure

(The figures give the number of pounds of fertilizing elements in one ton of manure,
including liquid, solid and bedding.)

Animal

Average
per cent
water

Nitrogen

(N)

Phosphorus

Potassium
(K)

Cow

78

9-10

2.5-3

6-8

Horse

63

10-15

2-3

8-14

Hog

74

11-13

5-6

6-12

Sheep * .

63

27-34J

3.5-5

20-23

Kent -

58

20

8

15

Made by fattening lambs.

from three states.

Feeding Affects Value of Manure. — The kinds of feed fed an
animal determine in a large measure the richness of the manure
produced. If a cow were fed timothy hay only, the manure would
be poor indeed as compared with that produced when a cow is
fed alfalfa, bran, corn, etc. When cows are fed bran, the

LIQUID PORTION OF MANURE VALUABLE

215

manure produced is necessarily enriched in phosphorus (Feed
table in Appendix).

The age of the animal also affects the value of manure. Grow-
ing animals remove much more elements, especially nitrogen and
phosphorus, from the ration than do mature animals.

The character and amount of bedding and litter also have much
to do in determining the value of manure. Sawdust and shavings
add little or no value, and may even lower the value of manure.

FIG. 144. — Dollars are trickling from this manure pile into the pond. No farmer can
afford to care for manure in this way.

The more bedding and litter incorporated with the excrement, the
more bulky the manure becomes.

Amount of Manure Produced by Farm Animals. — Roughly
speaking, it requires about twenty-five cows to produce a ton of
manure in one day, including what is actually collected in the
stables; about thirty-three to forty horses when kept in the stable
all day, and about sixty when they are working; 160 hogs; and
about 500 to 800 lambs when fed in the feeding pen.

Liquid Portion of Manure Valuable. — Of the total amounts
of the fertilizing elements contained in manure, about one-half
of the nitrogen and sixty per cent of the potassium are found in
the liquid excrement. Thus, the liquid manure is practically as
valuable in fertilizing elements as the solid. This fact emphasizes

216 NITROGEN, PHOSPHORUS AND POTASSIUM

the need of suitable absorbents to take up and conserve this
valuable fertilizing material.

Some Practical Pointers on Manure. — The results secured
in the use of manure do not come from the fertilizing elements
only, but also from the organic matter and the organisms added.
In one gram (one-fifth the weight of a nickel coin) of cow manure
voided in the stable have been found from a million to 120 millions
of organisms, and in horse manure from 100 to 150 millions.

Manure a Quick Fertilizer. — Manure has the quality of being

FIG. 145. — The manure from this dairy barn goes directly to the field.

a most effective fertilizer, largely because of the fact that it con-
tains immediately, medium, and more slowly available plant-food
material. About one-half of the nitrogen .is soluble, about one-
sixth of the phosphorus and about one-half of the potassium. This
makes manure a good fertilizer to use as a top-dressing on pastures,
hay land and clover and alfalfa fields.

Stall Manure Better Than Open-yard Manure. — Manure
hauled directly to the field and there applied is twice to three times
as valuable as that which has been allowed to accumulate in an
open yard for a period of from three to six months. Large amounts
of the fertilizing elements are leached out of open-yard manure by
rains. No farmer can afford to follow the practice of throwing
the manure carelessly from the stables into the open yard and there

WHEN MANURE HAS TO BE STORED

217

allow it to become exposed to the weather and the water from the
stable roof. Hauling it directly to the field or storing it properly
is universally recognized as the only way to get full value from the'
manure produced.

When Manure Has to Be Stored. — It is not always convenient
to haul it directly to the fields (Fig. 145). It then becomes neces-
sary to store and conserve it for future use. Three points should
be kept in mind in storing manure, viz.: (a) It should be kept
moist; (6) it should be kept well compacted, and (c) any loss of

FIG. 146. — A manure spreader increases the returns per ton of manure. (Indiana Station.)

seepage water from the manure pile should be avoided. Losses of
nitrogen from fermentation may be practically eliminated when a
manure heap is kept moist and compact.

The covered manure shed is a popular method of caring for
manure. Such a shed should be provided with a water-tight con-
crete floor and with sides sufficiently high to hold the manure in.
This may be called a manure pit. It should be so built that a
manure spreader (Fig. 146) can be run in at one end and out at
the other. The manure should be spread out on the floor and
allowed to be tramped on by the stock. Hogs may work it over
without danger of losses.

Manure is often allowed to accumulate in box stalls or in
covered feeding sheds. It is tramped on by the animals and kept

218 NITROGEN, PHOSPHORUS AND POTASSIUM

moist by the liquid excrement, sufficient bedding being used to
absorb the excess and to keep the stock clean. This is good prac-
tice provided the manure is hauled out in time and not allowed
to dry out and heat and decompose long after the animals have
been turned out to pasture.

When manure is stored in the open, it should be placed in a
pile having a flat top and nearly vertical sides. Never should the
manure within the pile get so dry as to cause "fire-fanging" or
burning. Piled as in Figure 147 it will heat.

FIG. 147. — Another farmer has forgotten that manure has a value.

Gardeners make use of compost heaps when they desire well-
rotted manure. Often other materials are mixed with the manure
when it is being piled, such as phosphate fertilizer, garbage,
garden wastes, etc., to make the manure a better fertilizer to meet
their needs. Hen manure can be better conserved and made a
more adaptable fertilizer to general trucking and gardening pur-
poses if twelve to fifteen pounds .of acid phosphate, four to eight
pounds of muriate of potash, and five to ten pounds of gypsum,
or land-plaster, were added to every 100 pounds of the fresh manure.

Manure cisterns and very deep pits are sometimes used to
store manure, especially the liquid. But because of the difficulty
in getting the manure out, comparatively few farmers in the
United States are using them.

Gypsum, or land-plaster, is often recommended as a conserva-

PLOWING UNDER VS. DISKING IN MANURE 219

tive material to mix with manure; but the results have not been
sufficient to encourage its use.9

Lime of any kind should not be mixed with manure when it
is being stored, because it favors fermentation. It also liberates
the ammonia.

Good Practice to Mix Horse and Cow Manures. — Horse
manure is a warm, dry manure, and cow manure, cold and wet.
The mixing of these two manures in a manure shed is advantageous,
since the one will absorb the liquid of the other, and the resulting
mixture is much more easily handled.

Light Applications Better Than Heavy. — It has been clearly
shown that, in general farming, it is better to use medium to light
applications of manure rather than heavy. In a thirty-five year
test made at the Pennsylvania Station, a twenty-ton application
per acre in a four-year rotation resulted in crop increases valued
at only $5.38 per acre more than when twelve tons were applied.
The applications were made twice in the rotation or at intervals
of two years, at the rate of ten and six tons per acre, respectively.
Corn, oats, wheat and mixed clover and timothy were the
crops grown.

Similar results were secured at the Ohio Station in a seventeen-
year test in which eight-ton and sixteen-ton applications, made once
in five years, were compared; and at the Indiana Experiment
Station, where comparisons were made between 14.2-ton and 8-8-
ton applications, extending through twenty-three years. These
results show that when the supply of manure is limited, it is better
to cover as much land as possible at the rate of six to eight tons
per acre than to get over comparatively few acres with a heavy
application (Fig. 148). Herein lies the great value of the manure
spreader (Fig. 146). It is also well worth remembering that
frequent light applications prove more profitable than heavy
applications at long intervals.

Plowing Under vs. Disking in Manure. — The plowing under
of manure is usually recommended, especially on the heavier soils,
largely because of the loosening effect produced in addition to
its fertilizing value. It is best to plow under coarse litter (in the

9 In a 15-year test made at the Ohio Station in which forty pounds of
gypsum were mixed with each ton of manure used, the average results showed
a gain, above the cost of the gypsum, of eighteen cents in case of yard manure,
and a loss of five cents per ton when it was mixed with stall manure. The
gypsum cost six dollars per ton.

220

NITROGEN, PHOSPHORUS AND POTASSIUM

fall), and it is easier to incorporate manure in a heavy soil by plow-
ing than by disking. Many tobacco growers have found it an excel-
lent practice to disk in a light application of manure on crummy
silt loams, in addition to the manure plowed under. On light soils
best results are usually secured when fine manure is disked in.

Concerning the Application of Manure to Clover Fields.—
It is often asked, "Is it not better to apply the manure as a top-
dressing to the clover field rather than apply it for corn ? "• This

.

^fe

A B C

FIG. 148. — The returns from one ton of manure. Eight-year average. A, Produce from one

ton yard manure; B, produce from one ton stall manure; C, produce from one ton

stall manure reinforced with 40 pounds of rock phosphate. (Ohio Station.)

can best be determined definitely on any particular field or farm
by trying out the two systems. Soil conditions may also determine
the course to follow.

Since soil improvement depends largely on the growing of
good clover, it seems best, when a soil is low in fertility, to apply the
manure as a top-dressing on the clover. This favors growth and
root development, so that more hay is secured for feeding, and a
better sod is formed which greatly increases the organic matter
of the soil when plowed under. A light application of manure on
the better clover sod produced in this manner, enables the produc-
tion of good corn or any other cultivated crop.

MANURE NOT A PERFECT FERTILIZER 221

When the soil is in a good state of fertility, applying the manure
for corn seems the better practice.

Concerning Winter Application. — The common opinion is
that severe losses occur when manure is applied to land during
winter. On steep hillsides there is danger of heavy losses, since
heavy rains and melting snow wash many of the small particles
of manure from the field. It is better, therefore, to apply manure
to steep hillsides just prior to plowing.

On level or gently rolling land, losses are generally quite small;
and, no doubt are much less than the losses which occur in the
average barnyard when the manure is allowed to accumulate there.

Residual Effect of Manure. — The beneficial effect of manure
on soils of the heavier types may be of long duration. The best
known experiment is the one made at an Experiment Station in
England (Rothamsted). For eight successive years manure was
applied to a piece of land at the rate of fourteen tons to the acre.
The land was then left in grass without manuring or fertilizing for
fifty years. The yields of hay were compared with those on a simi-
lar field on which no fertilization was made. The average increases
in yield for each decade, resulting from the previous applications
of manure, were fifty-seven, twenty-four, six, fifteen and twenty-
eight per cent, respectively.10

Manure Not a Perfect Fertilizer. — General results demon-
strate conclusively that manure alone cannot maintain fertility
nor can it be used exclusively in regenerating soils. The continued
use of such manure on many dairy farms has led to an unbalanced
condition in the soil. Oat crops especially, secure so much nitro-
gen that they lodge badly. Many dairy farmers who purchased
"run-down" farms, and who sought to improve the soil through
the use of manure, have found that phosphate fertilizers, in particu-
lar, are quite necessary to supplement the manure to give the results
desired. On sands, the reinforcing of the manure with both phos-
phates and potash proves most profitable.

Of all the materials that may be used in reinforcing manure,
there are none better than phosphate fertilizers. The Ohio
Station has produced conclusive results on this point. The follow-
ig table gives the average results of a fifteen-year test on silt
soil with manure reinforced with phosphates made at that
station (Fig. 148).

10 The Book of the Rothamsted Experiments, 1917, page 156

222 NITROGEN, PHOSPHORUS AND POTASSIUM

Net Value of the Increases per Ton of Manure Reinforced with Phosphates

Manure and treatment

Net value of
increases per

ton of

manure *

(Including

3 crops)

Yard manure (untreated) f

Stall manure (untreated)

Yard manure +40 pounds rock phosphate per ton .
Stall manure +40 pounds rock phosphate per ton . .
Yard manure +40 pounds acid phosphate per ton. .
Stall manure +40 pounds acid phosphate per ton . .

$2.55
3.31
3.54
4.49
4.10
4.82

* Eight tons of manure were applied to the acre once in a three-year rotation of corn,
wheat and clover. The yard manure was taken from the open yard, where it had been ex-
posed to the weather for 3 or 4 months during the winter. The stall manure was hauled
from the stable directly to the field and spread at once in the early part of winter. The
fertilizer was dusted over the manure-spreader loads.

t The cost of the fertilizer was deducted before computing the net values of increases
per ton of manure.

Though farming with livestock is recognized as an excellent
way to keep up the fertility, because of the opportunity of returning
to the land much of the fertilizing elements,11 yet it cannot be
assumed that because a farmer has stock on his farm he need
give no thought whatever to the future of his soil. Manure is
often poorly cared for, causing enormous losses annually. It is
evident that the farmer who understands the care, reinforcing
and proper use of manure will secure far greater returns from his
land, and be able to pass his farm on to others in a much better
condition, than the man who farms it without livestock or who
farms it without any definite plan for maintaining the fertility
of the soil.

Illustration Material for Lessons. — Have on hand four-quart samples of
the fertilizers important in your section. Include the four classes, also a few
miscellaneous samples.

Demonstrations. — Material Needed. — Enough unproductive soil to fill
8 two-gallon jars; 16 quarts of a light sandy soil; about 3 pounds of green clover
finely chopped, or its equivalent in dry clover chaff; 12 two-gallon jars; 3 one-
quart Mason jars; some corn and oat seeds; 8 grams each of sodium nitrate,
sodium acid phosphate and potassium sulfate; about 2 quarts of fresh horse
dung; and a few strips of red litmus paper.

11 It is commonly believed that when all crops are fed on the farm, and the
manure is carefully cared for and hauled to the fields, soil fertility can be
maintained indefinitely. This is impossible, because in the feeding transaction
unavoidable losses of the fertilizing elements occur — particularly of phos-
phorus.

LABORATORY EXERCISES

223

To Demonstrate the Beneficial Effect of Active Organic Matter in Soils. —

Procedure. — Mix with 16 quarts of a light, sandy soil an amount of green
clover equivalent to 3 tons of clover hay per acre. Put the mixture into 2
two-gallon jars, and plant one to corn and the other to grain. Fill two other
jars with the same soil, but without the green clover, and plant one to corn
and the other to grain. Observe results.

Questions. — (a) Why are legumes generally the best green manuring crops?

(6) Mention ways in which organic matter improves soil fertility.

To Demonstrate the Fertilizer Needs of an Unproductive Soil by a Pot
Fertilizer Test. — Procedure. — Thoroughly mix a quantity (enough to fill 8
two-gallon jars) of an unproductive soil and fill 8 two-gallon jars. (Provide
each jar with an opening at the bottom for drainage.) Number the jars and
treat them as follows:

Jar No. 1 — Give no treatment.
Jar No. 2 — Add 3 grams sodium nitrate (N).
Jar No. 3 — Add 3 grams sodium acid phosphate (P).
Jar No. 4 — Add 3 grams potassium sulfate (K).

Jar No. 5 — Add 3 grams each of sodium nitrate and sodium acid phosphate.
Jar No. 6 — Add 3 grams each of sodium nitrate and potassium sulfate.
Jar No. 7 — Add 3 grams each of sodium acid phosphate and potas-
sium sulfate.
. Jar No. 8 — Add 2 grams each of the three fertilizing salts.

The fertilizing salts may be pulverized and mixed with the soil. Plant
each jar to corn, place all in a favorable place, and observe results after about
4 or 5 weeks.

To Show that Ammonia is Given off from Fermenting Manure. — Pro-
cedure.— Put some moist horse dung into a quart Mason jar and keep it covered
in a warm place for about 2 days. Then hold a piece of moistened red litmus
paper over the mouth of the jar. Note odor of the escaping gas, and note
change in the color of the litmus paper. (Ammonia gas turns red litmus
paper blue.)

To Show How the Loss of Ammonia from Manure May be Reduced or
Largely Prevented. — Procedure. — Fill a quart jar about two-thirds full of horse
dung; wet with water, and tamp down well. Place in a warm place for about
2 days. Make similar tests as in the previous experiment.

Laboratory Exercises. — Material Needed. — Four-quart samples of at least
four of each class of commercial fertilizers; 3 tumblers; several strips of blue
litmus paper; a saucer; a little sulfuric acid; 5 one-gallon jars; enough loam
or silt loam to fill 5 one-gallon jars; a handful of corn; one-half cupful pulverized
peat; 2 flasks or vinegar bottles; and a few ounces of ammonium carbonate.

To Learn to Know the Common Commercial Fertilizers. — Procedure. —
Study the samples of fertilizers provided, and record observations, etc., in
tabular form as follows:

Class

Name of
fertilizer

Availability
of fertilizing
constituent

Per cent
fertilizing
elements

Character-
istics, odor,
color, physi-
cal condition,
etc.

Applica-
tion per
acre

Cost per
ton

N

P

K

(Keep in mind local conditions).

224 NITROGEN, PHOSPHORUS AND POTASSIUM

Questions. — (a) Which of these fertilizers are true salts?
(6) Which of these fertilizers should be used with special caution when
applied in the hill? Why?

(c) What is the difference between acid phosphate and rock phosphate?

(d) Which of the phosphate fertilizers is the most available?

(e) Is all the material composing acid phosphate soluble in water? (Try it.)
(/) How should rock phosphate be used for best results?

To Continue the Study of Acid Phosphate. — Procedure. — A. Place about a
teaspoonful of acid phosphate in a dish and pour on about a tablespoonful
of water. Mix thoroughly. Now dip a piece of blue litmus paper into the
mixture. What does this indicate? (Soluble phosphate salts are acid in char-
acter.) Should lime be mixed with acid phosphate and applied as a mixture?
(Consult text.) Why? Should acid phosphate and agricultural lime be
applied to the same soil the same season? Explain.

B. Weigh out five grams (the weight of a nickel) of rock phosphate.
Place it in a porcelain dish and add 5 grams of hot (130° F.) sulfuric acid.
(Handle acid with great care.) Stir well with glass rod, and note changes.

Questions. — (a) How is acid phosphate usually made?

(6) How does the resulting material compare with the acid phosphate on
the market?

(c) Tell briefly the steps in the manufacture of acid phosphate. (Consult
any book on fertilizer manufacture.)

(d) Should a farmer attempt to make his own acid phosphate from
rock phosphate?

To Study the Effect of Applying Commercial Fertilizers on the Seed in
the Hill. — Procedure. — Fill 5 one-gallon jars with loam or silt loam and plant
two hills of corn in each jar. Treat jars as follows:
Jar No. 1 — No treatment.

Jar No. 2 — Apply one-half an ounce of muriate of potash on the seed in
one hill, and one-half an ounce of a mixed fertilizer on the
seed in the other hill.
Jar No. 3 — Same as Jar No. 2, only apply the fertilizer in the soil on the

side of the hills.
Jar No. 4 — Apply one ounce of rock phosphate on the seed in one hill

and the same amount of mixed fertilizer in the other hill.
Jar No. 5 — Apply muriate of potash broadcast at the rate of 200 pounds
per acre. Mix the fertilizer well into the soil. Plant 4
kernels of corn. (One acre equals 43,560 sq. ft.)
Label jars properly, and place in the greenhouse. W^ater.
(Students may work in groups of five on this exercise.)
Questions. — (a) When corn is planted in hills 3 feet 8 inches each way,
how much mixed fertilizer should be applied per hill when 100 pounds are
applied per acre?

(6) What precaution should be observed in applying fertilizers in the
hill or drill?

To Determine Why Barnyard Water is Colored. — Procedure.— Every
farm boy has observed the peculiar color of barnyard water and has detected
strong ammonia odors in the horse stable. The one condition is closely related
to the other in this way: the nitrogen of an animal body is excreted through
the urine. The principal nitrogenous substance in urine is urea. Urea is
acted upon by fermenting organisms producing ammonium carbonate which,

QUESTIONS 225

with moisture, has the ability to dissolve organic matter. This accounts in a
large degree for the brownish color of barnyard water.

We can observe this solvent action in the following experiment:

Place a good tablespoonful of organic matter (peat) provided in each
of two flasks, and add 75 c.c. of ammonium carbonate solution to one and a
like amount of water to the other. Shake each well for five minutes, then let
stand for 20 minutes, after which time shake again for a few seconds. Run
the liquid contents through filters into tumblers and note color of liquids.
Explain results.

Home Experiments and Projects. — To determine the profitable use of
acid phosphate on soil deficient in phosphorus.

Procedure. — Apply 300 pounds of acid phosphate on an acre of soil needing
phosphate. Another acre beside this should be left unfertilized. Keep account
of all costs, measure yields, and compute net profits. (One-tenth acre plots
could be used as well.)

Other Fertilizer Projects. — To determine the effect of an application of
mixed fertilizer applied on corn at the rate of 125 or 150 pounds per acre, in
the hill, with a fertilizer attachment on the corn planter. A whole field of
corn may be fertilized in this manner, but leave at least 4 or 6 rows through the
field for a check. Determine increased yields at harvest time, and determine
profits in the use of the fertilizer (Figs. 137 and 138).

Tests may be made determining:

(a) The value of green manuring on sand or on any soil poor in organic matter.

(6) The value of manure reinforced with acid phosphate.

(c) The more economic use of manure when applied at the rate of 8 tons
per acre over a 16-ton application. Keep account of all costs, determine yields,
and compute net profits.

QUESTIONS

1. Discuss the importance of available plant-food elements in relation to

soil fertility.

2. What are the elements most considered in crop production?

3. What materials in a virgin soil contribute to the crop requirements of

nitrogen, phosphorus and potassium? Is this supply inexhaustible?

4. What is the theory of fertilizers?

5. What are the substances commonly used to add needed elements to soils,

or to render more available what is there?

6. Of what value is leaf -mold, grass, etc.?

7. What is meant by green-manuring? What are the benefits to be derived

through this practice?

8. Does green-manuring ever prove profitable? Is it always necessary to

apply green manure?

9. What are the best kinds of green manuring crops? Why?

10. Why is it important to maintain the organic matter in soils?

11. Name some crops used in green-manuring. Discuss their adaptability to

different conditions.

12. What are some points to bear in mind in plowing under green crops?

13. What crops usually follow green-manuring? Why?

14. Discuss the importance of green-manuring in soil improvement.

15. What should determine whether or not a crop should be plowed under

instead of being cut for hay? What is rowen?

15

226 NITROGEN, PHOSPHORUS AND POTASSIUM

16. In good soil management, is it necessary to sacrifice a crop (for green-

manuring) to make soil improvement possible? Explain.

17. What are commercial fertilizers? How are the fertilizing elements hi

fertilizers commonly expressed?

18. Name the four classes of commercial fertilizers.

19. Name the common nitrogen fertilizers, and mention some facts about each.

20. Are farmers to rely on nitrogen fertilizers as the source of nitrogen? Discuss

this point.

21. Name the common phosphate fertilizers. Tell of their phosphorus content,

and availability.

22. In what three ways may the fertilizing constituent of phosphate fertilizers

be expressed?

23. How is rock phosphate made? Discuss its use as a fertilizer.

24. What is basic slag? TeU of its use.

25. Compare ground steamed bone meal and acid phosphate as fertilizers

26. Distinguish between phosphorus, acid phosphate and phosphoric acid.

27. Discuss in general the necessity of fertilizing with phosphates.

28. In what special ways do phosphates affect crops?

29. A soil of low fertility was found to have lost one-half of its original phos-

phorus supply through exhaustive cropping. Is it absolutely necessary
to add phosphates to raise the phosphorus content to the original amount
before the soil can produce maximum yields? Explain. What kind of
fertilizer should be used during the first few years of improvement?
Later on what substitution may be made?

30. WTiat phosphate is best to use for top-dressing? When does bone meal

give best results? Basic slag? Rock phosphate?

31. Under what conditions do phosphates give best results on some soils?

32. Which seems the more profitable, rock phosphate or acid phosphate?

33. Name the common potash fertilizers, and give some facts about each

34. Distinguish between potassium and "potash."

35. Are potash fertilizers very generally used? What soils are particularly

in need of potassium? Name some crops requiring large amounts of
this element.

36. Discuss the use and value of wood ashes, muriate and sulfate of potash,

and kainit.

37. What are mixed and complete fertilizers? In practice, how are these

fertilizers designated?

38. What can be said of the use of mixed fertilizers?

39. Discuss the relation of commercial fertilizers to the maintenance of

soil fertility.

40. What really determines whether or not a farmer should use, or continue

to use, commercial fertilizers?

41. What are the factors determining the kind of fertilizer to use? Discuss

and illustrate.

42. Compare high and low grade fertilizers as to meaning and value.

43. What is to be said concerning home mixing of fertilizers? What materials

should never be mixed?

44. Discuss the ways in which fertilizers may be applied.

45. Are there ever any beneficial after-effects produced by commercial fertil-

izers? What makes this after-effect possible?

PROBLEMS 227

46. What is meant by manure? About what is the fertilizing value of a ton

of average farm manure? Are all manures of equal fertilizing value?
Illustrate.

47. Explain how feeding affects the value of manure.

48. Of what value is the liquid portion of manure?

49. What is the three-fold benefit derived through manure applications?

50. Why is manure such an excellent fertilizer?

51. Discuss the care of manure.

52. Which is more economical, light or heavy applications of manure? How

has this been demonstrated?

53. Should manure be plowed under for best results?

54. When is it good practice to apply the manure to the clover field?

55. Is winter application of manure a good practice?

56. Tell of the residual effect of manure.

57. Can manure alone be used in regenerating soils, or to maintain fer-

tility? Explain.

58. What is reinforced manure? What are some materials used for this

purpose?

59. What is the best reinforcing material for manure? Give a good illustration.

60. For an outline summary of this .chapter, see table of contents.

PROBLEMS

1. A man applied muriate of potash (43 per cent K) to a peat soil at the
rate of 100 pounds pier acre and grew 8 tons of silage corn per acre. Can he
maintain the potassium supply of that soil if he continuest his method of
fertilization for corn production?

2. A farmer applied a 3-12-4 fertilizer in the drill at the rate of 125 pounds
to the acre, and thereby increased his corn crop 10 bushels per acre. Should
he continue this practice?

3. "A" and "B" sell the same general grade of rock phosphate. A offers
his for $10 per ton with a guarantee of 13 per cent phosphorus. B sells his
for $12, guaranteeing a phosphoric acid content of 28 per cent. Who sells
the cheaper fertilizer?

4. A land owner wishes to compound a fertilizer containing 5.25 per cent
phosphorus and 10.5 per cent potassium for his marsh land. In what propor-
tions should he mix acid phosphate (7 per cent P) and muriate of potash
(42 per cent K)?

5. Compound a 2-8-3 fertilizer out of sodium nitrate (15 per cent N)
acid phosphate (7 per cent P) and muriate of potash (42 per cent K).

6. A silt loam contains 0.04 per cent phosphorus. Its original content was
0.09 per cent. How much acid phosphate (7 per cent P) would be required
to raise the phosphorus content of the soil to its original amount? How much
rock phosphate (13 per cent P)? (See question 29.)

7. Determine the approximate, normal prices of the following fertilizers
per ton: Sulfate of ammonia (20 per cent N), rock phosphate (30 per cent
P2O5), acid phosphate (16 per cent PzOs), nitrate of soda (15 per cent N),
kainit (14 per cent K20), muriate of potash (52 per cent K2O), and sulfate of
potash (50 per cent K2O).

8. At 15 cents a pound for nitrogen, 10 cents for phosphorus, and 8 cents
for potassium, determine the fertilizing value of sheep manure. Of good
nen manure.

228 NITROGEN, PHOSPHORUS AND POTASSIUM

9. A land owner grows corn averaging 65 bushels per acre, barley averaging
40 bushels per acre, oats yielding 50 bushels, red clover averaging 2 tons, and
timothy yielding 2 tons per acre, in a 5-year rotation. _He manures once in
the rotation, for corn, at the rate of 15 tons of average manure per acre.
Assuming no loss of fertilizing elements through leaching, can the farmer
expect to maintain the fertility of his soil by continuing this- practice? Would
it be possible if it were a 3-year rotation with oats and timothy left out?

10. In a test, some horse manure containing 10.2 pounds of nitrogen,
1.84 pounds of phosphorus, and 8.8 pounds of potassium per ton, was left
exposed to weathering for 6 months during the summer. During that time
36 per cent of the nitrogen, 50 per cent of the phosphorus and 60 per cent of
potassium were lost. Suppose 50 tons were thus exposed, what would have
been the total loss of each of the three fertilizing elements? Their total value
at 15 cents, 10 cents and 8 cents per pound, respectively?

11. In the table, page 222, determine the per cent increase in net returns
per ton of manure due to the use of phosphates as reinforcing materials.

CHAPTER XIII

SOIL ACIDITY AND LIMING IN RELATION TO FERTILITY

Soil Acidity Explained. — Many soils in humid regions are sour
or acid in character, because they manifest certain chemical
properties similar to acids. For example, an acid soil when
sufficiently moistened with pure, distilled water, turns blue litmus
paper1 red just as vinegar does, or the juice of an orange. This
condition is commonly spoken of as "soil acidity."

Soil Acidity Lowers Fertility. — Soil acidity is harmful in several
ways: (a) It causes a lack of available calcium (Ca) to meet the
demands of crops like alfalfa and clover; (6) it renders the plant-
food elements less available; (c) it favors the development of
malnutrition diseases, especially of truck crops; (d) it causes
soils to be less responsive to fertilizer and manure treatments, and
(e) it favors the growth of certain weeds. It is important, there-
fore, that soil acidity be corrected to increase productiveness.

Liming Defined. — The only economic way to correct soil
acidity is through liming. This means the application of neutraliz-
ing substances containing lime (CaO). In popular language
" agricultural lime" is a general name given these substances,
which may be either lime carbonates (CaO + carbon dioxide gas),
lump or burnt lime (CaO), or hydrated lime (CaO -|- water).
Whenever any such material is mixed in an acid soil, there begins
at once a chemical reaction between the "lime" added and the
soil, resulting in a disappearance of the acid conditions if a sufficient
amount be applied.

How Liming Improves Acid Soils. — Liming may improve
acid soils in several ways: (a) Available calcium is added; (b)
acidity and certain poisonous substances are neutralized, thus
creating an environment much more favorable to the growth and
.activity of the helpful soil bacteria, and to the growth of tender
roots; (c) plant-food elements in soils are rendered more available;
(d) greater returns are secured from fertilization; (e) the contin-
ued use of lime on acid clays and clay loams tends to improve their

1 Blue litmus paper is paper saturated with blue litmus, and is commonly
used as an indicator for acids. Litmus is a dyestuff extracted from certain
lichens. It has the property of turning blue in an alkaline solution and red
in an acid.

229

230 SOIL ACIDITY AND LIMING

structure, and hence favors the development of good tilth; (/)
weeds can be better controlled.

Calcium is to be regarded as an important plant-food element,
particularly in growing alfalfa, clover, peas, etc. Alfalfa fails on
an ordinary acid soil because it cannot secure sufficient calcium to
meet its needs. Such crops as corn and grain, on the other hand,
may grow quite well on acid soils, because there is still sufficient
calcium in such soils to supply the needs of these crops (table on
page 62; Figs. 149 and 156).

Any acids formed in soils through natural processes are neu-
tralized by lime if it is present. In soils certain substances other
than acids may be formed which may prove injurious if allowed to
accumulate. Lime destroys the poisonous effect of many of these
substances. The helpful soil organisms especially are injured
when soils become acid. Most of them favor soils that are suffi-
ciently supplied with lime. This explains why it is best to lime an
acid soil before it is inoculated, particularly for alfalfa.

It has been shown that plant-food elements are more available
in non-acid than in acid soils.- This is especially true in the case
of phosphorus. Often in a field of uniform silt loam, for example,
crops suffer for want of phosphorus on acid areas, while on the
areas not acid a phosphorus deficiency is not manifested—
even though the acid soil contains more total phosphorus than
the non-acid areas. Acid soils are generally in need of phos-
phate fertilizers.

It is wise economy to lime an acid soil if for no other reason
than to enable the soil to give greater returns from manure and
fertilizers. Some interesting results from the Ohio Station are
presented in the following table. These are the results of an experi-
ment extending through twelve years in a five-year rotation of
corn, oats, wheat, clover and timothy, on an acid, long-cropped
soil. This experiment is being continued.

These results, and many others, plainly show that liming is
the first step in the improvement of an acid soil.

When crops like alfalfa and clover fail, or are poor and thin
because of soil acidity, weeds have a better chance to grow, owing
to the fact that they meet with little or no competition. On the
other hand, when alfalfa and clover grow thick and strong under
favorable conditions as regards lime, etc., the weeds are smothered.
Sheep sorrel, or field sorrel, thrives especially well on acid fields
in which clover or alfalfa fails.

WHEN LIMING IS MOST PROFITABLE

Effect of Liming an Acid Soil

231

Average value of
crops per acre

Average cost of
lime and fertilizer

Net gain per acre

Treatment
(once in 5 years)

per rotation!

per acre per
rotation

per rotation

Unlimed

Limed

Unlimed

Limed

Unlimed

Limed

No manure, no fertilizer. .

$49.40

$61.40

$

$ 5.00J

$

$ 7.00

Manure (8 tons per acre) .

78.58

94.49

16.00

21.00

14.96§

25.87

Acid phosphate (320 Ibs.

per A.)

67.80

81.80

2.60

7.60

15.20

24.20

Complete fertilizer*

87.76

104.49

17.60

22.60

23.46

35.09

* Application per acre consisted of a mixture of 240 pounds nitrate of soda, 480 pounds
acid phosphate and 240 pounds muriate of potash.

f Corn was rated at 40 cents per bushel, oats at 30 cents, wheat at 80 cents, corn stover
at $3.00 per ton, straw at $2.00 and hay at $8.00.

t The equivalent of 4 tons of carbonate of lime (pulverized limestone) was applied to
the acre in the 12 years. Average cost, $3.00 a ton laid on the land.

§ Increases were calculated not on the average of all the unfertilized plots, but on the
average of two unfertilized plots, one on either side of a treated plot.

Liming Beneficial in Conjunction with Green Manuring. —

An acid soil is unfavorable to the decomposition of green-manuring
crops and to nitrification. Moreover, during the decomposition of
green crops plowed under, acids are formed, causing a temporary
increase in the degree of acidity. For most crops the presence of
lime to neutralize these acids as soon as they form proves bene-
ficial. At the Virginia Truck Station best results were secured
with peas and beans when lime was used in conjunction with cow-
peas plowed under green or dry in the fall. For best results it is
desirable, therefore, to lime an acid soil before planting a green-
manuring crop, or in some cases, to lime just after the crop is
turned under.

When Liming is Most Profitable. — Liming is most profitable
when growing alfalfa. It is common to obtain increases from 100
to 600 per cent in the growth of alfalfa by liming acid soils, or to
secure a successful producing stand over absolute failure (Fig. 149).
Seventy per cent of the alfalfa failures studied in Wisconsin in
the period from 1912 to 1917 were due to acid soils. Liming acid
soils for alfalfa, particularly,, may be the means of saving much
expense in hay production, since it is more economical to produce
twenty-five tons of alfalfa from five acres properly prepared than
from fifteen acres in need of lime.

Just liming alone has proved about as beneficial as manuring
in growing corn on some very acid, black, sandy soils.2

2 These soils are so strongly acid, farmers consider them barren.

232

SOIL ACIDITY AND LIMING

CQ £

"O O
S O

l

11

HOW TO TELL ACID SOILS 233

Liming, and also inoculation, may prove very profitable in
growing peas3 (Fig. 122).

Other Crops Benefited by Liming. — Aside from alfalfa, medium
red, Japan, and mammoth clovers, and peas, the following field
crops are directly benefited by liming when grown on acid soils:
Cabbage, sugar beets, tobacco, and to a lesser extent, soybeans,
barley, peanuts, hemp, muskmelons, and rape. The following
garden crops grow best on soils sufficiently supplied with lime:
Asparagus, common beets, celery, lettuce, onions, parsnips, peppers,
salsify, spinnach, and to a lesser extent, the eggplant.

Crops Which Tolerate Acidity. — There are many crops that
grow well on slightly or medium acid soils — lupines,4 cowpeas, vel-
vet beans, vetch, corn, potatoes, sweet potatoes, oats, wheat,
cotton, rye, buckwheat, alsike, crimson and bur clovers, beans,
millet, red top, watermelon, blackberry, raspberry and strawberry.

Alsike clover, soybeans, velvet beans, crimson clover and bur
clover are well adapted to acid soils, though they grow best on
limed soils, especially if strongly acid.

Certain citrus fruits, such as grape-fruit, are harmed by liming.
Other crops, like pineapple, have been injured by an excess of lime
on sandy soils.

In some cases, liming favors the development of certain crop
diseases, such as scab in potatoes; and in other instances it is the
best remedy — club-root in cabbage and nematodes on root crops,
for example.

The fact that there are many crops that can tolerate soil
acidity does not mean that they are not benefited in any way by
liming. Most of these crops respond to liming because of its
general renovating effect. When clover, for example, is benefited
through the use of agricultural lime and a prime sod is produced,
the crops following must necessarily be increased because of the
better clover and improved soil conditions. It is fortunate, never-
theless, that there are so many good crops that can tolerate
slight to medium degrees of soil acidity, since soil acidity is so
prevalent in humid regions.

How to Tell Acid Soils. — Acid soils may be determined in
different ways, as follows:

3 A 3-year test at Columbus, Wisconsin, gave an average increase of 32.4
per cent due to liming alone. Field had been inoculated. Soil, silt loam.

4 Lupines generally do not respond to liming, but are frequently injured,
instead. Cowpeas seem to grow well without liming.

234 SOIL ACIDITY AND LIMING

(a) By the Use of Blue Litmus Paper. — This method consists
in allowing well-moistened soil to come in contact with blue litmus
paper, which can be secured of any good druggist. When the soil
is moist from rain or on thawing, make a slit in it with a clean
knife blade and insert one end of a piece of blue litmus paper,
then press the soil over it and allow it to stand for fully three
minutes. If the paper becomes pink in spots or over the whole end,
the soil is acid.

This test may also be made by placing the litmus paper hi
between two halves of a ball of wet soil; and, also, if the soil is
dry, by placing a small amount of soil in a clean dish and moisten-
ing it with boiled, soft water to a stiff mud. By means of a clean
stick, the litmus paper is placed between two portions of the
wet soil.

Another way is to place a strip of blue litmus paper on a piece
of clean window glass, make a mud ball, break it into halves, place
one of the halves flat side down over the paper on the glass, press
the soil down firmly, and allow it to stand for five minutes.

Precautions. — Do not mistake a fading of the blue color of
the paper as an acid reaction; the change of color should be from
blue or light blue to pink or pink-red. Keep the litmus paper,
when not testing, in the dark and in a clean bottle or box. Do not
allow the portion of the litmus paper which is to be placed in the
soil to come in contact with perspired fingers or hands. Perspira-
tion is acid in character. Use water that has been previously boiled.

The litmus paper test is simple and reliable for field use, but
it cannot determine the " degree" of acidity very accurately.

(b) By Chemical Tests. — Several chemical tests may be used,
not only to detect an acid condition, but also to determine the
degree of acidity and the amount of lime necessary to correct
this condition.5

(c) By Alfalfa and Clover Failures. — Since alfalfa and medium
red and mammoth clovers are more or less "sensitive" to acidity,
the failure of these crops usually indicates acid soils (Fig. 149).

(d) By the Growth of Certain Plants. — Peat beds on which
blueberry, huckleberry and cranberry grow are acid. Uplands on
which blueberries grow are also acid. Clover and alfalfa fields

5 The Truog Soil Acidity Test devised at the Wisconsin Station may be
mentioned as a simple and accurate test for determining the degree of acidity
in soils, and the amount of agricultural lime to use in specific cases. Simple
apparatus for making this test may be purchased of school supply houses.

HOW TO TELL ACID SOILS

235

Fia. 150. — Two weeds that thrive on acid soils when clover or alfalfa fails. To left, horse-
tail rush; to right, sheep sorrel, or horse sorrel. (Wisconsin Station.)

236 SOIL ACIDITY AND LIMING

infested with sheep sorrel, horsetail rush (Fig, 150), common
plantain, paintbrush, corn spurry and wood horsetail are usually
acid. The fields become infested with such weeds because the
soil conditions are unfavorable to the clover or alfalfa.

Conversely, soils on which alfalfa, sweet clover and the June-
berry grow are usually not acid. Marsh lands, or other low soils,
which become thinly coated with a white substance invariably are
not acid (Fig. 151). This white substance in humid climates is
usually mild alkali.

FIQ. 151. — This marsh soil is not acid because it becomes coated with a thin, white coating

of mild alkali.

Low Wet Lands Not Necessarily Acid. — It is commonly
believed that all low, wet soils are sour. In a general sense, there
is no relation, whatever, between wet lands and acidity. In
sections in which both acid and non-acid soils occur, the low soils
are the least acid or not sour at all; either because of seepage which
brings carbonate of lime and other substances to the surface, or
because carbonate of lime is washed down from the surrounding
uplands, as in a limestone country.

Acidity is rarely found in soils or valleys which are frequently
flooded by streams coming from limestone regions.

Peat and muck soils surrounded by high, limestone soils are

ACID SOILS ARE EXTENSIVE

237

generally not acid, or only slightly so; whereas those in sections
where limestone is absent are generally strongly acid.

How Soils Become Acid. — Soils become acid when they lose
carbonate of lime and other substances of a similar chemical
nature. In mineral soils, deficiency of carbonate of lime is brought
about by leaching and cropping. Leaching is the greater factor.
Certain determinations have shown that on ordinary cropped
fields the total amount of lime removed annually by leaching is
equivalent to 300 to 500 pounds of carbonate of lime per acre to
a depth of four feet. From uncropped, cultivated fields the losses
may double these amounts.

FIQ. 152. — Soil acidity is increased by dust from zinc-ore roasters. Vegetation in back-
ground destroyed by sulfur fumes. (Wisconsin.)

In undrained peat and muck soils, acidity develops through the
accumulation of acids resulting from the decomposition of the
organic matter; and in drained and cropped peats, deficiency of
lime may be brought about in the same manner as in mineral soils.

Acid Soils Are Extensive. — The great majority of soils of the
East, South and portions of the Middle West are in immediate
need of liming, not to mention extensive areas elsewhere. Three-
fourths and more of the soils of New York, Wisconsin and Indiana
are acid ; most of the soils of Massachusetts have not sufficient
lime for highest productivity; the soils of the greater portion of
Tennessee are acid ; large areas of Missouri and Oregon are in need
of liming; the same may be said of Georgia, Mississippi and
other states.

238 SOIL ACIDITY AND LIMING

The Nature of Soil Acidity. — In practically all upland, acid
mineral soils, the acid characteristics are imparted to them mainly
by insoluble acid substances which in themselves are soil particles.
In such soils, therefore, reduction of acidity through leaching
is impossible.

In some cases, upland soils may be acid because of the accumu-
lation of certain organic or mineral acids (Figs. 152 and 153).

In undrained, cumulose soils, acidity is due, in a large measure,
to the presence of soluble organic acids which may be largely
leached out when the marsh is thoroughly drained. On low sand
islands in undrained acid marshes, the soils are usually strongly
acid because they are saturated with the organic acids from the
surrounding peat. When the marshes are drained these sand
islands become less acid. Permanent acidity in peat must neces-
sarily result from the presence of insoluble, acid organic substances.
Loss of lime increases the acidity of drained, acid peats.

Kinds of Agricultural Lime. — Many materials are suitable for

liming soils, such as:

' a. — Pulverized limestone.
6. — Air-slaked lime.
c. — Marl.
d. — Waste lime.
e. — Pulverized shells.
/. — Marble dust.
g. — Pulverized coral.
h.— Chalk.

B. Lump or burnt lime (CaO).

C. Hydrated lime (CaO+water)

Pulverized Limestone. — Strictly speaking, limestone is calcium
carbonate (Fig. 154). When a rock consists of a combination of
calcium and magnesium carbonates it is called magnesian lime-
stone or dolomite. The name " limestone" is commonly applied
to both rocks. Limestone may be distinguished from other rocks
by the fact that it gives off bubbles of gas when treated with dilute
acid (muriatic acid). This is a common test for any carbonate.

Limestone is prepared for direct agricultural use by crushing
and pulverizing (Fig. 155). When it is pulverized so that about
fifty to sixty per cent of the material will pass through a sixty-
mesh sieve6 it may be considered of standard fineness (Fig. 156).
The fine material produces immediate action in soils, while the

6 A 60-mesh sieve means a sieve having perforations & of an inch
in diameter.

A. Carbonates of lime (CaO+CO2)

PULVERIZED LIMESTONE

239

FIG. 153. — Soil acidity caused by mineral acid. Sulfide sludge washed over bottom-land.
Weathering of sludge destroyed vegetation. (Wisconsin.)

FIG. 154. — A limestone quarry. A source of agricultural lime.

coarse particles give to the soil a reserve of lime carbonate. The
best grades of limestone contain from 90 to 100 per cent carbonates.

240 SOIL ACIDITY AND LIMING

In sections far from railroads and from limestone-pulverizing
plants, and in which outcrops of good limestone occur, farmers
may find it much more economical to pulverize their own limestone
by using small pulverizing machines (Fig. 157). Limestone is
often found on farms where the fields are acid (Figs. 158 and 159).

FIG. 155. — Limestone pulverizers are built on the swing-hammer principle.

Limestone screenings from crushed rock are frequently used
for liming. Sometimes this material is as fine as pulverized lime-
stone, but more often it is rather coarse, and hence slow acting.

Magnesian limestone in general is equally as good as pure
limestone for liming.

Pulverized limestone is considered best to use on sandy soils.

PULVERIZED LIMESTONE

241

*?•'

FIG. 156. — Limestone converted into soil improvement material. This soil is acid even
though it is underlaid by limestone.

FIG. 157. — This farmer is pulverizing his own limestone for soil improvement.
16

242

SOIL ACIDITY AND LIMING

FIG. 158. — This farmer found a good outcrop of excellent limestone.

strongly acid.

Most of his soils are

FIG. 159. — A soil derived from limestone and underlaid by crumbled limestone. This
soil is acid to a depth of three and one-half feet, within two inches of the rotten limestone.

Air-slaked Lime. — This is formed when lime used in making
plaster and mortar is exposed to the air. On exposure, the carbon
dioxide gas of the air is absorbed and this action converts the lime

LUMP OR BURNT LIME 243

into lime carbonate again. Air-slaked lime is usually finely divided
and can be applied directly to the land.

Marl is a name given to earthy deposits, usually more or less
friable in character and containing varying amounts of carbonate
of lime. Marl beds are usually found in marshes. If a farmer
has a deposit of good marl and his soils are acid, he can utilize
such a deposit as a source of agricultural lime. Marl should be
allowed to air-dry before using (Fig. 8).

Pulverized kiln-dried marl may be purchased for liming in
some sections.

In New Jersey, the term "marl" is applied to Greensand
material which contains some potassium. Deposits of shells
partially disintegrated and more or less cemented together are
found in some localities. Such deposits are commonly called
" shell marl."

Waste lime is a by-product from industries, such as lime-
kilns, gas works, paper mills, beet sugar factories, tanneries and
water-softening processes. Some of this material may contain
substances that might be injurious to plant growth ; and sometimes
it is very wet, making its application difficult and transporta-
tion unprofitable.

Pulverized Shells and Coral. — Oyster shells, clam shells, and
coral, when cleaned of dirt and organic matter, contain from
ninety to ninety-five per cent carbonate of lime. When pulverized
these make excellent materials for liming. Shell dust may be
secured in some places as a waste product from button and chicken
grit factories.

Marble Dust. — In the East, limited amounts of marble dust
as waste from marble works are available. This is high-grade
liming material.

Natural chalk is carbonate of lime that has been deposited
in much the same way that marl has been. Chalk has been used
to a considerable extent in European countries. In this country
such deposits are of insufficient extent to be considered a source
of agricultural lime.

Lump or Burnt Lime. — This is quick or caustic lime — the
most concentrated form of lime that may be used. It is produced
by heating limestone to a red heat in kilns, thus driving out the
carbon dioxide gas and leaving the common lump lime. This form
of lime can be procured in every town. When used in proper
amounts little or no injury can come from its use, especially on

244 SOIL ACIDITY AND LIMING

the heavier soils. It should be finely ground, water-slaked or
air-slaked before applying. When lump lime is finely ground
the term " ground lime" is given it.

Lump lime for agricultural use is more generally used in the
Eastern States than in the Middle West.

Hydrated Lime. — When lump lime is treated with water or
steam, in the absence of air it becomes a powder quite like ground
lime in appearance, if the proper amount of water or steam is
used. The names "hydrated lime," "limoid" and "lunate" are
given this product by manufacturers. It is finely divided and
ranks next to lump lime in concentration. This material is not
commonly purchased for liming.

Land-plaster Cannot Correct Acidity. — Land-plaster, or gyp-
sum, is sulfate of lime, a material quite different from carbonate of
lime. Under certain conditions it supplies calcium and sulfur as
plant-food elements, but when pure it has no value in correcting
acidity. Usually common land-plaster contains a trace of car-
bonates as impurities, but not enough to give it any value
as a neutralizer.

Comparative Value of Agricultural Limes. — The neutralizing
value of any material used in liming depends upon its content
of lime (CaO) or the equivalent in carbonates, and on its fineness.
Pure limestone, for example, contains fifty-six per cent lime (CaO),
or it is 100 per cent lime carbonate — forty-four per cent being
carbon dioxide gas (CO2). It is the calcium and magnesium or
their oxides (CaO and MgO) which produce the beneficial effect
in acid soils; and the finer the material, the quicker the action.
Accordingly, the comparative value of the different forms of lime
may be stated as follows:

(a) On the basis of lime content — one ton of lump lime equals
1.3 tons of hydrated lime equals 1.8 tons of carbonate of lime.

(6) On the basis of neutralizing value when dry and of equal
fineness — one ton of lump lime equals 1.3 tons of hydrated lime
equals 1.8 tons of carbonate of lime.

(c) On the basis of quickness of action, considering pulverized
limestone as it is commonly used — one ton of lump lime finely
divided is equal to about three tons or more of pulverized limestone.

Finely pulverized limestone is much more effective than coarsely
crushed limestone.

Best Material for Liming. — For first application to benefit
special crops like alfalfa, it is desirable to use finely divided

WHEN AND HOW TO APPLY LIME

245

material. Coarse material may be used for subsequent applica-
tions. For quick results, lump lime, hydrated lime or finely
divided air-slaked lime may be used. Pulverized limestone, marl,
ground shells, or marble dust is usually preferred on sandy soils.
Lump and air-slaked lime may also be used, but never in excessive
amounts. On acid peats and mucks, lump lime, hydrated lime and
fine air-slaked lime are good.

Ordinarily, the best agricultural lime to use is that material
which is finely divided and which contains the most lime, or car-
bonate equivalent, in a dollar's purchase (all cost and labor to
get it applied to be considered). It is important, therefore, to
know the moisture and lime, or carbonate, content of any material
before buying. Whenever agricultural lime is secured through
transportation, it is cheapest to purchase it in carload lots.

Amounts of Lime to Apply. — The following rates of application
to the acre may serve as guides in liming:

One ton pulverized limestone, marl

On light soils (per

acre)

Of slight acidity

Of strong acidity

or shell dust (preferred)
500 to 1000 pounds lump lime or 1

ton air-slaked lime
Two to 4 tons pulverized limestone,

marl or shell dust (preferred)
One to \1A tons lump lime, or from

2 to 3 tons air-slaked lime

tons pulverized limestone,

On the heavier soils
(per acre)

f One to
(Of slight acidity On<™

{ or hydrated lime

ton lump

Two to 4 tons pulverized limestone,
or other carbonate. (Heavy appli-
cations for crops like alfalfa, clover
Of strong acidity \ and peas)

One and one-half to 2 tons lump
lime. (Especially good for clay
loams and clays)

The coarser or more wet the material, the heavier should be
the application.

Poor acid soils are in greater need of lime than rich acid soils.

When and How to Apply Lime. — In liming it is well to remember
that the place for lime is in the soil and not on top of it; and the
more thoroughly it is mixed with the soil, the better the results.
Commonly, the full effect does not show until two to four years
after the lime application is made. Any rational method whereby
lime may become thoroughly incorporated in the soil is recom-
mended (Fig. 160).

246

SOIL ACIDITY AND LIMING

Liming should be done previous to planting the crop to receive
the direct benefit. To be most effective, lime should be applied
to plowed land and thoroughly mixed in by harrowing or disking.
Application may be made at any convenient time. It is good prac-
tice, when alfalfa and clover is to follow corn, to apply the lime
when the ground is fitted for corn, particularly if a carbonate form is
used. In so doing the acidity is much reduced before the alfalfa or
clover is sown. In such cases pulverized limestone may be conven-
iently applied by spreading it over the spreader-loads of manure.

FIG. 160. — Applying lime with a lime spreader.

Lime is most conveniently applied through the use of lime
spreaders (Fig. 160). When only a few acres are to be limed at a
time, the material may be spread by hand directly from the wagon
if it is damp enough to prevent excessive blowing; otherwise it is
best to place the material in small piles, then spread it over the
ground by means of shovels.

Lump lime is best applied by placing it in small piles about
two rods apart each way on plowed ground. If a ton, for example,
is to be applied to the acre, fifty pounds should be placed in each
pile. When the lime becomes slaked, it is spread and disked.
It is usually best to shovel the pile over at least once to facili-
tate slaking.

Dry air-slakod lime, quicklime, hydrated lime and kiln-dried

CROPPING CONSERVES LIME 247

marl are disagreeable to handle because of the dust inhaled.
Wearing a moist sponge over the nose is a good precaution.

Applying Lime As a Top-Dressing. — The application of finely
pulverized limestone, marl and thoroughly air-slaked lime as a
top-dressing on sandy soils for young clover or alfalfa may prove
quite beneficial, though best results may be obtained by liming
the plowed field sufficiently before seeding. The openness of a
sandy soil enables the fine lime particles to be carried down more
or less into the soil. Top-dressings on heavy silt and clay loams
have not given satisfactory results, for these soils do not permit
the entrance of lime particles as do sandy soils.

Sometimes a farmer wishes to lime his spring's seeding of clover
on open silt loam, for example. In such a case, partially air-
slaked or hydrated lime, finely divided, applied at the rate of a ton
and a half or two tons to the acre early the following spring before
the frost is out may prove beneficial. Such an application should
not be made after the young plants have started their new year's
growth, because sufficient caustic lime may be present in the mate-
rial to injure them.

The application of lime as a top-dressing for pasture and per-
manent hay lands rarely proves profitable. The lime, exposed to
rain as it lies on the firm surface, loses its fine physical state, and
is taken but slowly into the body of the soil.

How Often to Lime. — The effect of even a moderate application
of lime on an acid soil lasts a number of years. Leaching experi-
ments have shown that the lime added to an acid soil does not
leach out so rapidly as is commonly believed. Some experiments and
field tests have shown that when agricultural lime is mixed into the
top six inches of an ordinary acid soil, it passes downward very slowly.

On some fields which were limed more than ten years ago, the
effect of the lime seems to be just as apparent now as then. When
an acid soil is given an application of lime sufficient to neutralize
all the acidity in the surface six or eight inches, subsequent liming
may not be necessary for many years. The need of more lime can
easily be determined by testing the soil for acidity.

Cropping Conserves Lime. — On an acid silt loam at the Cornell
Station, New York, an application of burnt lime, at the rate of
3000 pounds per acre, did not increase the amount of lime found
in the drainage waters from that soil.7 These leaching experiments

7 Cornell Sta. Memoir 12, 1918. The soil was acid in the first 3 feet and
not acid at the fourth foot in depth.

248 SOIL ACIDITY AND LIMING

show an average annual loss of about 433 pounds of carbonate of
lime per acre to a depth of four feet when the land is cropped, and
a loss of 918 pounds per acre when the land is left bare without any
vegetation. The equivalent of thirty-three pounds of carbonate
of lime was removed by the crops. Thus the equivalent of 452
pounds of carbonate of lime was conserved by cropping the
land. These experiments show that cropping conserves the lime
in the soil as compared with the same soil left bare, and that the
annual loss of carbonate of lime per acre to a depth of one foot is
probably not much more than about 108 pounds when the land
is cropped.8

Deep Plowing Cannot Be Substituted for Liming. — It is some-
times reasoned that the lime which leaches out of the soil is caught
and held in the subsoil, and that if the land is plowed deeply, this
lime can again be brought to the surface. When soils are medium
to strongly acid, this is impossible, since to a depth of a foot or
more the subsoil is just as acid as, or more acid than, the first
six or eight inches of surface soil.9

Residual Soils from Limestone Become Acid. — It is usually
difficult for farmers in certain sections in which are found soils
derived from and underlaid by limestone to understand how it is
possible for them to become acid. Frequently in such cases the
carbonate of lime has been so thoroughly leached out of them that
the subsoils to depths of fifty inches or more, or to within two or
three inches of the rotten, underlying limestone, possess extremely
high degrees of acidity (Fig. 159).

The Surface Soil the Critical Zone. — It is a common belief
that soil acidity has a direct injurious action on the roots of
plants. Alfalfa, if any, would be most affected, since it so often
fails because of acidity. On the contrary, no such injury has ever
been found in ordinary acid soils.10 Again, it is often thought

8 Illinois Station concludes that the equivalent of 540 to 760 pounds of
carbonate of lime is leached from the surface 21 inches of soil annually.
111. Bui. 212, 1919.

9 Based on the Truog test for acidity. Author's conclusions based on the
tests of more than 300 samples of soil collected in 6-inch zones from more than
50 widely scattered fields. '

10 Hundreds of alfalfa roots extending into deep, strongly acid subsoils
have been examined by the author on widely scattered fields. Recent investi-
gations at the Wisconsin Station show that the acidity of the plant sap is
sometimes higher than that of most acid soils. The acidity within the root,
therefore, is often greater than that outside in the surrounding soil.

USE AND MISUSE OF LIME 249

that it is unnecessary to lime an acid soil underlaid by limestone,
because the plant roots would quickly penetrate deep enough to
feed on the carbonate of lime. Numerous experiments show clearly
that when an acid soil is limed and the material thoroughly incor-
porated in the surface five to eight inches, alfalfa can be grown
most successfully; and if not limed, failure results, regardless of
the facts that the acid soil may be underlaid at depths of two feet
or more by partially decomposed limestone, and thorough inocu-
lation made (Fig. 149).

Alfalfa Can Grow Well on Rich Acid Soils. — In some sections
it is not rare to see most excellent crops of alfalfa growing on quite
acid soils without liming and inoculation. These are either
tobacco fields which have been heavily manured annually for
several years, or rich and well-drained new lands. In either case
the alfalfa feeds on the soil as corn does, for example — being able
to secure its requirements without liming and without the aid of
nitrogen-fixing, nodule organisms. In some of these fields the
alfalfa roots were fairly well supplied with nodules, though not
nearly so well as compared with alfalfa growing in normal non-
acid soils:

Usually, however, it is profitable to lime even these soils as
well as those only slightly acid when growing alfalfa. It has also
been found that the richer the soil the higher the degree of acidity
alfalfa can tolerate.

Not Necessary to Neutralize All Acidity at Once. — Some soils
are so strongly acid that it would be prohibitive to apply sufficient
lime to neutralize at once all the acidity in the surface six or eight
inches. For most general farm crops it is not necessary. In such
cases, a three-ton or four-ton initial application of pulverized
limestone, for example, may be sufficient to give desirable results
(Fig. 149).

Use and Misuse of Lime. — The use of lime in agriculture is
perhaps one of the most striking illustrations of the tendency on
the part of the farmer to seek some panacea, or cure-all, for soil
ailments. Its use in farming dates back to 1100 B.C., and earlier.
History shows that in some places liming has been encouraged and
again discouraged, doubtless because of its misuse. The two
following quotations are good illustrations:

"Now that this lime [meaning lump or quicklime] is of
excellent use, and wonderful profit, do but behold almost all the
Countries of the Kingdom where there is any barrenness, and you

250 SOIL ACIDITY AND LIMING

shall find and see how frequently Lime is used, in so much that
of mine own knowledge in some Countries where (in times past)
there was one Bushel made or used, there is now many loads, and
all risen from the profitable experience which men have found
in the same." (Published in London, Eng., 1660.)

"We must guard against its [referring to lump or quicklime]
abuse, for it has been abused terribly hi times past, so much so
as to give rise to two dictums — inexact it is true: 'Lime enriches
the father and impoverishes the son'; and again, 'Lime once and
make a fortune. Lime twice and lose it/ In either case the blame
ought not to be put on the lime, but on the person who has abused
it. It would be better to say, 'When lime has impoverished the
soil it is because the farmer does not know how to use it. ' ' (Pub-
lished in London, Eng., 1916.)

Too much should not be expected of agricultural lime. It
contains no nitrogen, phosphorus or potassium,11 and hence it
cannot supply any of these elements. It alone can never maintain
fertility or restore a depleted soil to its original productive-
ness. An eminent liming authority12 in this country has written
the following:

"Lime will not take the place of fertilizer or manure; on the
contrary, lime will only produce its full effect on land that has been
previously well fertilized or manured."

Fertility Regulated Through Liming. — The benefits to be
derived through liming are so fundamentally important that
sufficient lime in the soil may be regarded as a fertility regulator.
Its proper use in increasing crop production and in maintaining
fertility presupposes the presence of a good supply of nitrogen,
phosphorus and potassium. Just lime alone, therefore, is not the
only material to add to a depleted soil to grow good clover or alfalfa,
or to regenerate that soil. Liming is a necessary first step towards
improvement, to be supplemented or followed by the use of phos-
phate fertilizers, manure, green manure and, on some soils, a
general use of fertilizers including potassium. Lime, acid phos-
phate, and manure may be added the same season. It is best,
however, to mix the lime thoroughly into the soil before applying
any soluble phosphates. An old slogan said: "Lime and lime
without manure makes both farm and farmer poor."

"Waste lime from beet-sugar factories contains small amounts of
these elements.

12 Director Thome of the Ohio Station.

LABORATORY EXERCISES

251

Whenever liming alone increases general crop production,
fertilizer needs become more urgent, since the increases make a
heavier draft on the soil reserve of the plant-food elements.

Though there are many crops that can tolerate acidity, yet
most of them will respond to liming because of the favorable con-
ditions created within the soil by the added lime. It is, indeed, a
deplorable fact, that in some sections farming without the use of
agricultural lime represents much waste of time, money and effort.

Illustration Material for Lessons. — Show 3 forms of agricultural lime —
burnt lime, hydrated lime and air-slaked lime (carbonate of lime).

Show 2 or 3 other lime carbonates.

Show a good grade of pulverized limestone, or other forms of agricul-
tural * lime.

Demonstrations. — Material Needed.— -Several strips of blue litmus paper;
a little vinegar; an orange; an apple; a little ammonia water; a pint each of
strongly acid upland soil and undrained acid peat; a Truog soil-acidity testing
outfit; a small baking-powder can; a bottle of muriatic acid; several materials
containing lime carbonate; 12 tumblers; a 20-mesh screen; a 100-mesh screen;
2 tablespoonfuls of coarsely crushed limestone; and a teaspoonful of very finely
pulverized limestone.

To Demonstrate the Reaction of Acid Substances, Including an Acid
Soil, on Blue Litmus Paper. — Procedure. — With blue litmus paper test the
reaction of vinegar, of water, ammonia water, apple juice, orange juice, and
of strongly acid soil.

Question. — When is a soil said to be acid or sour?

To Demonstrate the Truog Acidity Test. — Procedure. — Follow directions
accompanying testing outfit.

A. Demonstrate the reaction of a strongly acid soil.

B. Test the same soil, only use hard water instead of distilled water. Ex-
plain results.

To Demonstrate the Nature of Soil Acidity. — Procedure. — A. Fill a small
baking-powder can with an acid sandy soil. (Perforate the bottom and place
a piece of cheese cloth over the bottom.) Allow about 4 quarts of hot soft
water to percolate through the sand. Dry a sample and retest for acidity.
Compare the results with first test.

Question. — Why is it not possible to wash out the "acidity" in the
sandy soil?

B. Repeat the experiment and use 'an undrained acid peat soil. Ex-
plain results.

To Show How to Test for a Carbonate. — Procedure. — Put a teaspoonful of
lump lime into a tumbler and pour on it about a tablespoonful of dilute muri-
atic acid. Repeat test and use air-slaked lime, limestone, shells, coral, etc.

To Demonstrate that the Fine Material in Pulverized Limestone is the
Quick-acting Material. — Procedure. — A. Obtain about 2 teaspoonfuls of
crushed limestone (from a sample of pulverized limestone) that will not pass
through a 20-mesh screen. Wash this coarse material thoroughly several
times with acidulated water to remove all adhering fine particles. Obtain a
teaspoonful of fine material that will pass through a 100- or 200-mesh screen.
Fill a tumbler half full of water and add a few drops of muriatic acid to make
distinctly acid to blue litmus paper. Mix thoroughly. Pour one-half of the
acid solution into a second tumbler. Into one put the two teaspoonfuls of
coarse particles of limestone, stir, and let stand 30 or 45 minutes, then test

252

SOIL ACIDITY AND LIMING

again with blue litmus paper. Into the other tumbler pour the teaspoonful
of the fine material, stir for a few seconds, and test with blue litmus paper.
Explain results.

B. Repeat the test but use pure gypsum (calcium sulfate) instead of the
finely pulverized limestone.

Laboratory Exercises. — Material Needed. — Several small strips each of
blue and red litmus paper; 8 tumblers; about a cupful each of 3 soils to test
for acidity; a half cupful each of a common salt solution, soapy water, vinegar
solution sweetened with sugar, and sour milk or whey; four or five saucers;
a piece of window glass; a small amount of pure gypsum (calcium sulfate);
4-quart samples of agricultural limes; a bottle Of muriatic acid; and a quart
of coal ashes.

To Determine the Reaction of Different Solutions by the Use of Litmus
Paper. — Procedure. — A. Dip a small piece of blue litmus paper into an acid
solution provided. What happened? Try a piece of red litmus paper. Any
reaction? Acid turns blue litmus paper red.

B. Dip a piece of blue litmus paper into an alkaline solution. Any reac-
tion? Test with a piece of red litmus paper. What change takes place?

An alkaline solution turns red litmus paper blue. An alkaline solution
has an opposite reaction to that of an acid solution.

C. Test pure water with blue and red litmus paper.
Water is a neutral material, neither acid nor alkaline.

D. By the use of blue and red litmus paper determine the reaction of the
following solutions:

A common salt solution; soapy water; vinegar solution sweetened with
sugar; and sour milk or whey.

Question. — -What is litmus?

To Test for Soil Acidity by the Use of Blue Litmus Paper — Procedure. —
A. Place about 3 tablespoonfuls of soil in a clean saucer and moisten to a thick
mud with clean, soft water, previously boiled. With a clean stick separate
the mud into two portions and lay on one portion a piece of blue litmus paper.
Press the other portion of wet soil firmly down on the paper; leave for about
3 to 5 minutes, then carefully remove the upper portion of the soil and examine
the paper. Note results, and interpret.

B. Test another soil, but this tune place the piece of blue litmus paper
between the two halves of a mud ball.

C. Test a third soil. This time lay litmus paper on a piece of window
glass, and cover with one-half of a mud ball.

To Show that Lime Will Correct Soil Acidity. — Procedure. — A. Place
about three tablespoonfuls of acid soil in a clean saucer and thoroughly mix
with it about a quarter of a teaspoonful, or less, of air-slaked lime. Moisten
the mixture and test with blue litmus paper as before. (Select either one of
the three methods.)

B. Repeat and use pure gypsum (calcium sulfate) instead.

Question.— What effect did the lime have on the acid soil?

To Study Different Forms of Agricultural Lime. — Procedure. — Examine
carefully the samples of different agricultural limes provided and record facts
and observations in tabular form as follows:

Common
name

Carbonate,
hydrate or
quick lime

Application
per acre

Cost
per ton

Characteristics: color,
fineness, moisture
content, carbonate
content

QUESTIONS 253

Test the different materials for carbonates by placing about a quarter
of a teaspoonf ill in a tumbler and pouring on a few drops of dilute muriatic acid.

Questions. — (a) What kind of gas is given off when a carbonate is treated
with acid?

6) What becomes of much of this gas after it escapes into the air?

c) What is a carbonate?

d) Name three carbonates.

(e) What kinds of carbonates are present in pure limestone, wood ashes,
and air-slaked lime?

(/) Would you use coal ashes as a neutralizer for acid soils? As a fertilizer?

Home Experiments or Projects. — Object. — To demonstrate the profitable
use of agricultural lime on acid soil for alfalfa, clover, lespedeza or peas.

Procedure. — Select an acre or half an acre of well-drained acid soil. Divide
into two portions. Thoroughly lime one plot and leave the other plot unlimed.
Sow alfalfa, peas, lespedeza or common medium red clover. Inoculate both
plots. Determine to what extent the use of lime increased the value of the
land as an income producer. (Consider the crop grown.) Determine net
profits in the use of lime (Fig. 149).

To Demonstrate the Need of Both Lime and Phosphate on a Long-
cropped Acid Soil. — Procedure. — Select an area of acid soil, divide into two
strips, and lime, as described in above project. After the lime is thoroughly
mixed into the soil by disking, apply acid phosphate on one-half of each
strip at the rate of 300 pounds per acre. "Drag" the fertilizer into the soil.
Plant corn the first year, grain the second, and clover the third. Apply 200
pounds of acid phosphate for grain the second year. Apply the fertilizer to
the same end receiving the phosphate for corn. Do not fail to inoculate the
whole area for the clover.

Determine the net profits from liming and the use of lime and phosphate
for the 3-year period.

Field Studies. — 1. Collect sample of soils from a few fields showing indi-
cations of acidity and test for acidity either in the field or laboratory.

2. Collect samples of soil from areas growing good clover or alfalfa and
from areas where the clover or alfalfa failed or is growing poorly. Test the
soils for acidity.

QUESTIONS

1. What is the meaning of soil acidity?

2. Why is soil acidity harmful? How can this condition be corrected?

3. What is meant by liming? Agricultural lime?

4. Discuss the beneficial effects of liming.

5. Under what conditions does green manuring give best results?

6. What crops in particular give most direct profits from liming? Name

other crops benefited directly by liming.

7. Name several crops especially adapted to "acid agriculture."

8. Besides clover, a farmer grows corn, wheat, oats and timothy in a five-year

rotation on acid soil. If he were to lime his land could he expect profit-
able returns from the other crops as well as from the clover? (Table,
page 231.)

9. How may acid soils be determined?

10. Describe the blue litmus paper test for acidity.

11. How may certain weeds indicate acidity?

12. What relation is there between soil acidity and low wet lands? Discuss

this point.

13. How do soils become acid?

14. How extensive are acid soils?

15. Can soil acidity be reduced through leaching? Explain.

254 SOIL ACIDITY AND LIMING

16. Name several kinds of agricultural lime. Into what three groups may

they be classified?

17. What is limestone and how is it prepared for agricultural use? What is a

test for limestone, or for any carbonate?

18. What may be considered standard fineness for pulverized limestone?

19. When may farmers find it economical to pulverize their own limestone?

20. What is air-slaked lime? How does it differ from limestone?

21. What is marl? Waste lime? Tell of their values.

22. What are lump Hme, ground lime and hydrated lime?

23. What may be said of lump lime for liming?

24. What is land plaster? Can it be used to correct soil acidity?

25. Compare the value of lump lime, hydrated lime and carbonate of lime as

regards lime content^ neutralizing power and quickness of action.

26. What is the best material to use for liming?

27. How much lime should a farmer apply to his acid soil?

28. What facts should guide in determining the time and manner of apply-

ing lime?

29. How may agricultural lime be applied?

30. Should a farmer apply lime as a top-dressing?

31. How often should lime be applied?

32. Why cannot a farmer, instead of liming, plow deep and turn up the carbon-

ate of lime leached from the surface soil?

33. Can residual limestone soils become acid? Explain.

34. Does soil acidity have any direct injurious effect on the roots of

plants? Discuss.

35. Is it necessary to inject lime into the subsoil for best results? Explain.

36. Under what conditions can alfalfa grow well on acid soils without any

special treatment? In such cases does liming prove beneficial?

37. A farmer finds his soil requires the equivalent of six tons of pulverized lime-

stone to completely neutralize the acidity in the seven inches of surface
soil. Is it necessary to add that much Hme in the first application?

38. What gave rise to such a saying as "Lime enriches the father and impover-

ishes the son"?

39. Discuss the proper use of lime in relation to soil improvement and fertil-

ity maintenance.

40. Give an account of a particular case of liming about which you know.

Give the effects.

PROBLEMS

1. Determine the per cent increase in net profits per acre per rotation due
to liming for each of the fertilizing treatments indicated in the table, page 231.
Determine the net profits per acre in the use of lime alone.

2. About how many tons of lump lime may be made from twenty tons of
good limestone?

3. A small field 12 rods square is to be given an application of one ton of
lump lime to the acre.

(a) How many pounds of lump lime would be required?

(6) For convenience, the lime is to be spread from small piles placed two
rods apart each way. How many piles should be made in the field? Draw a
diagram of the field to a scale of one-fourth inch equals a rod, and indicate the
placing of the piles.

(c) When each pile becomes thoroughly air-slaked, how many pounds of
material would there be in each pile? The application of lump lime would
be the equivalent of how many pounds of carbonate of Hme for the field?

CHAPTER XIV

HARMFUL AGENTS IN SOILS AFFECTING FERTILITY

"ABSENCE of harmful agents in soils" is the one negative
factor named with the positive factors determining soil fertility.
Water, air, good tilth, helpful soil organisms, and available nitrogen,
phosphorus, potassium and sufficient lime are all necessary to
create within the soil the power for producing large crops; but
the presence of any harmful agents may nullify the effect of all
these positive factors. In considering a case of low yield or infer-
tility, it is important, therefore, not only to examine into the posi-
tive factors determining fertility, but that investigation be extended
to a consideration of harmful agents within the soil as well. Some
of these harmful agents are discussed in the following paragraphs —
not fully but sufficiently to illustrate the importance of this nega-
tive factor.

Worms and Insects May Destroy Crops. — Frequently a farmer
is at a loss to know why some particular crop should " stand still"
or fail when all conditions seem favorable. The white grub, wire
worm, the corn rootworm, the maggot, and eel worms or nema-
todes are common " worms" that live in the soil and which often
injure crops by feeding on their roots.

White Grub. — In some fields, as in southwestern Wisconsin,
northeastern Iowa and northwestern Illinois, the white grub often
causes complete loss of the corn crop. It may also cause much
injury to timothy, potatoes, lawns, strawberries and beans. These
grubs are the larvae, or the young, of the May beetles or "June
bugs." They feed on the roots of various plants and on potato
tubers. Early October plowing will destroy many of these grubs.

The wire worm is the young of the click beetle, and is generally
harmful to corn on old sod. These worms, like the white grub,
live in the soil two years before they change into the beetle form.
This explains why the wire worm often causes more injury the
second year after an old sod is broken than the first year.

Corn Rootworm. — Corn growers in the Southern states, particu-
larly, suffer much damage from the corn rootworm or "bud worm."
In some seasons it is difficult to get a stand of corn in the lowlands
on account of these worms which are but the young of the twelve-

255

256 HARMFUL AGENTS IN SOILS AFFECTING FERTILITY

spotted cucumber beetle. These worms are slender and yellowish-
white with a dark-brown head. They not only feed on the corn
roots, but in young corn they bore into the stems and eat the inte-
rior, boring out the crown, and killing the bud. Burning over waste
places and growing other crops on fields badly infested, thick plant-
ing and enriching the soil are suggested remedies.

Root Maggot. — Some truck crops, such as cabbage, radish and
onions, are injured by the maggot (Fig. 161). Other crops are
injured by eel worms or nematodes which cause the root-knot

FIG. 161. — Injurious work of maggot on radish. (Geneva Station, N. Y.)

disease, as on cabbage and tomato (Fig. 162). The growing of
other crops has been found the most effective remedy.

The aphis (a'fis) is a common insect which injures crops.
There are many species, many of which feed on the juices of plant
roots.1 The corn root-aphis, or root-louse, is perhaps the best
known. Ants are largely responsible for aphis injury to roots,
since they carry the eggs of these insects into the soil and care for
them in their nests. When the eggs hatch the ants tunnel into
the ground and place the helpless aphids first on the roots of cer-
tain weeds, such as smart weed, then on the corn roots (Fig. 163).
Aphids are often called "ant cows." Since the corn root-aphis

1 Cotton and asters are also commonly injured by the corn root-aphis.

CROP DISEASES MAY CAUSE FAILURE

257

usually attacks corn that is grown continuously on the same land,
crop rotation is an effective means of control. Another complete
and effective means of controlling the corn root-aphis is thorough
stirring of the soil previous to planting, to disturb the ant colonies
and scatter and kill the aphids.

FIG. 162. — Roots of tomato plant affected with root-knot. (Florida Station.)

Crop Diseases May Cause Failure. — A great many diseases
attack plants. Many of them are caused by fungi and bacteria
which live in the soil; among which may be mentioned potato scab,
pea blight,2 wilt, root rot, cabbage yellows, brown rot in tomatoes,
black-leg in cabbage and cauliflower, and club root (Fig. 164), soft
rot and black rot, as in cabbage. Rotation of crops and avoiding

2 Pea blight fungus stays in the soil so long as diseased tissue of the pea
plant remains in the soil. Potato scab on the potato may be treated, but
when soils become infested with the scab fungus other crops should be grown.

17

258 HARMFUL AGENTS IN SOILS AFFECTING FERTILITY

disease infested fields are remedies suggested to control these
diseases or to avoid injury from them. Sometimes plants may be
developed that are resistant to certain diseases. Cabbage resistant
to yellows is a good illustration (Fig. 165).

Too Much Water Is Harmful. — On lowlands the harmful
effect of too much water is commonly observed, but the lack of
proper drainage on some upland fields having good surface drain-
age is very often least suspected. Frequently certain fields or
portions of them are found to grow good crops of hay and grain

FIG. 163. — Diagram showing how ants foster the corn root-aphis. Upper right, the corn
root-aphis, enlarged. (U. S. D. A.)

but fail in growing corn, in spite of the fact that manure and
fertilizers may have been added. In almost every case the cause
of the poor corn is due to seepage water from higher land, which
keeps the subsoil too wet and cold to favor the growth of corn.
Tile drainage is the remedy (Fig. 166).

Alkali Is Injurious. — In regions of deficient rainfall, alkali
in soils often proves injurious, and in some sections in humid
climates, alkali spots occur. Frequently the irrigation of land in
irrigated sections causes the accumulation of salts near the surface
(being brought up from the subsoil through capillary rise of applied
moisture) in sufficient amounts to cause the most fertile lands to

ALKALI IS INJURIOUS

259

become unproduc-
tive. Other lands in
the arid and semi-
arid sections are so
saturated with alkali
salts naturally that
they are barren, and
are not fit lands for
irrigation. The per-
manent remedy con-
sists in removing the
injurious salts by
means of tile drains,
scraping it off, and by
flooding. The grow-
ing of alkali-resisting
crops, such as salt
grass, has been sug-
gested as a means
of avoiding injury.
Sweet clover grows
well when alkali is
quite abundant. As
a general rule, deep
rooted plants can
tolerate alkali soils
better than those
that are shallow
rooted. Land-plaster
is sometimes used
to neutralize black
alkali, the most
harmful of the alkali
salts (sodium car-
bonate). Retarding
evaporation by
mulching and shad-
ing, and deep plow-
ing may retard the
accumulation of salts
at the surface.

FIG. 164. — Club-root of cabbage, showing swollen and dis-
torted roots and.undeveloped head. (Vermont Station.)

260 HARMFUL AGENTS IN SOILS AFFECTING FERTILITY

•

FIG. 165. — A soil infested with cabbage yellows. A strain of cabbage has been developed
to resist this disease. Two rows to left are non-resistant cabbage. (Wisconsin Station.)

FlG. !§(?. —

Unproductive spot on a low field due to high water-table. Variation in sub-
soil the cause of the difference in water-table.

THE TOXIN THEORY OF INFERTILITY

261

The Toxin Theory of Infertility.3 — A few investigators are
supporting the theory that infertility of many soils is due largely
to the presence of certain poisons or toxins which probably owe
their origin to plant-root excretions and to decomposition of soi|
organic matter. The supporters of this theory maintain that the
beneficial effect of fertilizers on poor soils is due to the power of.
the fertilizers to neutralize or counteract the effect of these toxins,
rather than to the available plant-food elements added.

167. — Diseased wheat on wheat-sick soils. Dead roots and blighted leaves.
40 years in wheat. (North Dakota Station.)

Soil

They have presented data endeavoring to show that increasing
the amount of available plant-food elements through the use of
fertilizers has practically nothing to do with the maintenance of
soil fertility. This theory, however, has been accepted by only a
few, since other investigators have shown definitely that soils
which produce large yields contain more available plant-food
material than do soils that produce low yields. Furthermore,
'numerous field tests have demonstrated that crops on poor land
are directly benefited by fertilizers and lime.

Nevertheless, it is conceded that some toxins do form in soils

3 Conclusions drawn by Whitney and Cameron of the Bureau of Soils,
United States Department of Agriculture.

262 HARMFUL AGENTS IN SOILS AFFECTING FERTILITY

and which may prove injurious to certain crops and fruit trees
if allowed to accumulate. Recent investigations seem to show
that most soils are so constituted that through good drainage,
proper tillage and the presence of sufficient lime the injurious
action of these toxins may be entirely or in a large
measure prevented.

Other Harmful Agents. — Among other harmful agents that
have been named in certain instances to explain low yields or fail-
ures are: (a) An excessive amount of aluminum and iron in soils
renders some of the plant-food elements unavailable. The effect
of soluble phosphates on certain red, tropical soils is of short dura-
tion because of the presence of excessive amounts of iron and
aluminum; (b) too much magnesium in proportion to calcium
may disturb the normal function of plant cells; (c) too much lime
in some soils may prove harmful to some crops, as grape-fruit,
pineapple and certain lupines; (d) certain mineral acids may make
soils sour; (e) it is advocated by some that certain soil micro-
organisms accumulate to such an extent that they greatly retard
the activity of the helpful soil organisms.

Collect specimens showing the work of insects which attack roots of crops in
any way. Specimens of these insects may be collected and preserved according
to directions given in many good insect books.

Diseased root specimens of field crops may be brought to class and kept
for study. v

Projects in growing crops in spite of insects and diseases should be con-
ducted, using the most approved methods in each case.

QUESTIONS

1. What negative factor should be considered in diagnosing a case of infertility?

2. What may some of these agents be?

3. Discuss infertility due to worms which feed on plant-roots.

4. Name methods of control.

5. What is the corn root-louse?

6. Name some plant diseases caused by certain fungi and bacteria that live

in soils.

7. How may a farmer avoid crop failure due to these diseases?

8. Explain how too much water within soils may prove a harmful agent.

9. Suggest a remedy.

10. Illustrate by diagram.

11. Discuss the relation of alkali to soil fertility.

12. What is the toxin theory of the infertility of many soils?

13. What are toxins?

14. According to this theory, what is the action of fertilizers?

15. Do any poisonous substances form in soils? How?

16. What do recent investigations seem to show as regards these toxins?

17. What harmful agents in soils do you know from your own experience

or observation?

CHAPTER XV

CROP ROTATION AND ITS RELATION TO SOIL FERTILITY

Crop Rotation Defined. — Crop rotation is a system of growing
different kinds of crops in recurring succession on the same land.
For example, on a certain field a farmer grows clover one year,
corn the second, oats the third, clover the fourth, corn the fifth,
oats the sixth, etc. This is a three-year rotation, since each crop
recurs every third year. Another farmer may grow these same
crops in a rotation as follows: clover followed by corn, then another
crop of corn, which in turn is followed by grain seeded to clover.
This is a four-year rotation since it requires four years for the
complete succession of these crops to recur.

Some systems of cropping are designated as fixed rotations, and
others as definite rotations.

A fixed rotation is a system of cropping in which the different
crops recur at regular intervals, and which occupies a fixed number
of years. Clover followed by potatoes, then rye seeded to clover,
is a good example of a fixed three-year rotation practiced by some
potato growers on sandy soils. Some fixed rotations may occupy
four years, others five and six years or more.

A definite rotation may be defined as a system of cropping in
which the different crops continually recur in a definite order,
but is not fixed as to the number of years it occupies. Many
farmers, for example, grow alfalfa, corn and grain on the same land
in the order named, in anything from a five-year to a ten-year
rotation — alfalfa three to six years, corn one to two years, and
grain one to two years. Another common, definite rotation is,
hay (clover) followed by pasture, then corn, then grain seeded to
clover and grass. In such a rotation the land may be pastured one
to three years.

Very often in a rotation some one crop is grown two or more
years in succession; as, tobacco (three years), followed by wheat
(one year), clover (one year), tobacco (three years), etc.

Nearly all farmers practice crop rotation in some form or other.
Comparatively few adhere to fixed rotations, since they prefer
to follow a cropping system that is more or less flexible so that a
shift can be made when prices or seasonal variations should make

263

264 CROP ROTATION

necessary a change in the cropping plan. Moreover, varying soil
conditions and the desire of the farmer to meet feeding require-
ments often prevent the establishment of a fixed rotation for the
entire farm.

One-crop System. — In contrast to crop rotation is the
one-crop system in which one kind of crop is grown year after year
on the same land. This is often called "continuous cropping."
There are many examples of this in the corn belt, wheat belt, cotton
belt, etc.

Why Crops Are Rotated. — Crop rotation has largely been the
outgrowth of farming experience. Its beneficial effects have long
been known, though the reasons were not understood. Even
today some of the effects of crop rotation are not clearly under-
stood. The primary object of rotation is to increase crop pro-
duction and to help maintain productive farming. This is the
cumulative effect of several specific benefits derived through this
practice, which are: (a) It helps to eliminate injury due to certain
insect pests; (b) it aids greatly in avoiding injury from certain
diseases; (c) it favors the accumulation of soil organic matter;
(d) tilth may be improved; (e) it favors the conservation of
fertilizing elements; (/) it aids in solving certain liming and
fertilizing problems; (</) weeds are better controlled.

Rotation Controls Certain Insects and Plant Diseases. —
Many truck growers, particularly, much prefer to grow certain
crops continuously on the same land, because when the soil is
fitted to meet the requirements of a special crop it is easier to
succeed with it. This explains the tendency to grow crops like
cabbage, sugar beets, onions, and in some localities, potatoes,
on the same land several years in succession. Though it is conven-
ient at times to practice a one-crop system with certain crops,
yet general experience teaches that it is a wiser plan to practice
rotation, since many records show that certain pests and plant
diseases finally compel the farmer to rotate. Some crops are
especially attacked by certain soil-dwelling insects or are pecu-
liarly susceptible to certain diseases which may infest the soil.
The continuous growing of one crop favors the development of
some such insect or disease until finally the crop is unable to resist
its attacks. The growing of other crops not affected by the
particular insect or disease must necessarily result in the soil
becoming rid of the insect or disease, because these other crops do
not favor its development nor its continuance in the soil.

PROPER ROTATION INCREASES ORGANIC MATTER 265

Some potato growers have experienced the destructive effect
of potato scab on fields growing potatoes continuously (Fig. 168).
This disease can be prevented through seed disinfection; but
when the soil is allowed to become infested by planting untreated,
scabby potatoes, no remedy is so effective as crop rotation in
eliminating the disease. The unfortunate experience of the pioneer
farmer in growing wheat continuously on the same land might
well be remembered as a warning against the one-crop system.

Proper Rotation Increases Organic Matter. — It is a striking
fact that the growing of intertilled crops greatly hastens the
destruction, and hence the loss, of the soil organic matter. It is
not wise, therefore, especially on soils low in organic matter, to

FIG. 168. — Scabby potatoes the result of no clover or green manuring in rotation
(sugar beets, cabbage, potatoes). This condition developed in six years. No scab on pota-
toes grown in rotation with clover. (Clover, potatoes, corn, oats.)

practice a rotation consisting of all intertilled crops, without the
introduction of clover, other legumes, and green-manuring crops to
maintain the supply of this very necessary soil constituent. A
rotation including clover or pasture, and in which manure and
green-manuring, or catch and cover crops are systematically used,
increases the soil supply of organic matter. The introduction of
non-cultivated crops such as grain, hay and pasture, lessens its
destruction, and the use of manure, the development of good sod
(Fig. 169), and the plowing under of green crops are ways to add
it to the soil. A carefully planned crop rotation is the most con-
venient method whereby something definite may be done to main-
tain the soil organic matter. It is entirely possible for practically
every farmer to plan a rotation or rotations which will enable him
to accomplish this.

266

CROP ROTATION

Proper Rotation Improves Tilth. — The rapid depletion of the
soil organic matter resulting from the growing of crops without
clover and without the use of manure and green-manuring crops
has a destructive effect on good tilth. Sandy soils become much
looser; and the heavier soils lose their crummy structure, becoming
more compact, and easily puddled when worked in a wet condition,
A rotation which maintains and builds up the supply of organic

FIG. 169. — The development of good sod increases the soil organic matter. A , root develop-
ment on land properly fertilized; B, root growth on same land but unfertilized.

matter in the soil also improves the workability of soils and
maintains good tilth. The growing of grass, pasture and deep-
rooted legumes on heavy soils greatly aids in improving their tilth.
On a portion of a field (silt loam) at the University of Illinois,
corn was grown continuously for forty years; while on another
portion, during the same period, a three-year rotation was prac-
ticed, consisting of corn, oats and clover. The soil on the first
portion has become compact, it "runs together" badly, and heavy

ROTATION AIDS IN FERTILIZATION AND LIMING 267

rains wash it considerably and pack it, forming a smooth, hard sur-
face. The other portion, on which were grown clover, corn and oats
in rotation, is mellow, has a crummy structure, and heavy rains do
not affect it as they do the soil on the first portion. The difference
in these two plots is largely the result of the growing of clover.

Conserving Fertilizing Elements Through Rotation. — Not all
crops require the same amount of the different plant-food elements.
Some are gross feeders, and others make heavy drafts upon one or
two elements1 (see Table of Crop Constituents, Chapter VI) . Cab-
bage and spinach, for example, quickly exhaust the soil of nitrogen.
Inn rotation it can be arranged that one crop requiring a large quan-
tity of one element, or all of them, does not follow another of a
like characteristic. Through rotation, therefore, the draft upon the
soil reserve of nitrogen, phosphorus, and potassium may be equal-
ized so that the productive power of soils may be prolonged.

The growing of such crops as tobacco and cabbage and all
shallow-rooted crops without rotation causes heavy losses of plant-
food elements through leaching. These crops require rich soils, and
hence heavy fertilization becomes necessary. The soil is supplied
with much more available material than the crops can use, and
hence conditions are favorable for heavy losses through leaching.

In Wisconsin, a study was made of the phosphorus losses on
sixteen tobacco fields. These fields were cropped, on an average,
forty-six years — thirty of which were tobacco. During this time
they received an average of thirty applications of manure at the
rate of eighteen loads, or about twenty-seven tons, to the acre.
These investigations showed that during the forty-six-year crop-
ping period, this system of farming caused the loss (above that
removed by the crops) of an amount of phosphorus per acre from
the surface soil eight inches deep, sufficient to supply the phos-
phorus needs of at least seventy 75-bushel corn crops-.

When deep-rooted crops such as corn, alfalfa, clover and vetch
are grown in rotation with shallow-rooted plants, much of the
fertilizing elements which leach down into the lower strata is
utilized. Moreover, deep-rooted plants bring up considerable
plant-food material that is, in turn, used by other crops. This is
especially true when soils are more or less "open" in character.

Rotation Aids in Fertilization and Liming. — Rotation offers
an opportunity to get the greatest returns from manure and com-
mercial fertilizers by applying them to the crops which can make
the best use of them. Much coarse, fresh manure or litter gives

268 CROP ROTATION

best results when it is plowed under in the fall for corn. Under
certain conditions the application of manure to the clover fields
gives best results.

Some believe that liming tobacco lands results in lowering the
quality of the leaf. Results do not seem to support this view,
however. Furthermore, experiments have shown that tobacco
responds readily to liming when grown on acid soils. When tobacco
is grown on acid soil in a rotation containing clover, the lime need
not be applied directly to the tobacco crop, but for the clover
instead. In this way any possible injury caused by the direct
effect of lime on tobacco may be entirely prevented. In case of
potatoes, the lime may be applied in the rotation immediately
following the potato crop. Other similar problems concerning
liming and the use of fertilizers may be solved through rotation.

Rotation Controls Weeds. — It has been demonstrated as well
as commonly observed that fields on which small grains are grown
continuously become very weedy, and crops diminish in yield and
even fail as a result. This is because most weeds go to seed in the
time required for the grain to mature. The growing of intertilled
crops is a most effective way to kill weeds, especially those such as
quack grass and Canada thistle. The growing of good clover and
alfalfa, or any other leafy forage crop, is another effective way to
kill the common weeds and keep them under control. A rotation
containing at least a cultivated crop and one good clover crop
gives the farmer at least two good chances in his system of cropping
to fight the weeds.

Rotation Helps to Maintain and Increase Fertility. — In the
foregoing discussion it is plain that a proper rotation of crops
affects favorably, either directly or indirectly, practically all the
factors which determine soil fertility. When these factors are
thus affected, soils necessarily produce better crops. In this
manner, therefore, rotation aids in maintaining and increasing
fertility — that is to say, crop rotation helps to maintain and in-
crease the productive power of soils. The productive power of a
soil is reduced more rapidly when a crop is grown on it continu-
ously than when a rotation is practiced. Among the many rota-
tion experiments that may be cited to prove this, those in progress
at the University of Illinois may be selected as typical. The fol-
lowing results are available from the oldest rotation experiments
in America. These plots are located on brown silt loam, the typical
prairie land of the corn belt. (Illinois Station circular No. 193.)

ROTATION HELPS TO MAINTAIN FERTILITY

269

Crop Rotation Helps to Maintain Productive Power of Soils
(No soil improvement treatment of any kind made)

Year the
experiment

Cropping system

Yield af
ave

ter 36 years
rage 1906-1

10-year
915

Per cent greater
crop value per acre
over no rotation

was begun

Clover

Corn

Oats

(average for 10-
year period,
1906-1915)

1879

Corn continuously
Corn and oats in
rotation ...

Tons

Bus.

28.8
37.5 *

Bus.
380 *

180

Clover, corn and
oats in rotation

1.69

57.6 f

33.4J

36.7

* Five-year average, t Three-year average, t Four-year average.

The yield of corn at the beginning of the experiment was seventy
bushels. After thirty-six years of continuous corn culture this
yield was reduced nearly 59 per cent; and only 17.7 per cent
reduction occurred when corn was grown in rotation with clover
and oats. The first twelve years of continuous corn growing
reduced the yield to thirty-five bushels, after which the decrease
amounted to only eight bushels in sixteen years. It is thought
that the rapid reduction in yield during the first twelve years
was due, in a large measure, to the destruction, and hence deple-
tion, of the soil organic matter.

The fact that the average annual crop value per acre for the
ten-year period, 1906-1915, was 36.7 per cent greater when clover,
corn and oats were grown in rotation than when no rotation was
practiced is further proof of the advantage of a rotation in main-
taining a higher productive power. The higher average crop value
for the clover-corn-oat rotation over the corn-oat cropping plan
was due largely to the increased yield of corn produced by growing
clover in the rotation, and not to the value of the clover as a
money crop.

Many farmers have experienced more profitable crops when
they substituted a rotation for a one-crop system, or when a good
rotation coupled with a definite plan of fertilizing is put into
practice on a depleted soil. This latter point has been definitely
demonstrated in an experiment started in 1894, at the Ohio
Station, on silt loam soil which had been previously rented for
twenty-five years, and hence badly depleted (Bulletin 282).

270

CROP ROTATION

Proper Rotation With Use of Fertilizers Increases Productive Power of a

Depleted Soil

(Yield of corn grown in a 5-year rotation)

Cropping system

Soil treatment

Average
yield for
first
5-year
period
1894-1898

Average
yield for
fourth
5-year
period
1909-1913

Decrease and
increase in yield
in 20 years
(per cent)

Corn continuously
Corn in 5-year ro-
tation*
Corn continuously

No treatment

No treatment
Commercial fertilizers
(mixed) . (250 Ibs.
per crop)f

Bushels

26.26
31.89

38.86

Bushels
8.44

20.31
26.83

67.8 decrease
36.3 decrease

30.9 decrease

Corn continuously

Corn in 5-year ro-
tation

Manure (5 tons per
acre per year) ....
Commercial fertilizers
(mixed) (985 Ibs.
for each 5-year
period)!

43.13
35 78

30.22
44 10

30.0 decrease
23 2 increase

Corn in 5-year ro-
tation

Manure on corn and
wheat (8 tons per
acre, or 16 tons per
rotation

40.73

55.83

37.0 increase

* Rotation consisting of corn, oats, winter wheat, clover and timothy grown in the
order named.

t Sixty pounds of acid phosphate, 30 pounds of muriate of potash and 160 pounds of
nitrate of soda applied annually.

t One hundred sixty pounds of acid phosphate and 80 pounds each of muriate of potash
and nitrate of soda applied to corn and oats crop; and 160 pounds acid phosphate, 100
pounds muriate of potash, 25 pounds dried blood and 60 pounds nitrate of soda applied
to each wheat crop.

It is interesting to note that the yield of corn decreased thirty
per cent in twenty years when grown continuously, even though
manure was applied at the rate of twenty-five tons for each five-
year period. In the rotation, on the other hand, the yield increased
thirty-seven per cent during the same period, manure being applied
at the rate of only sixteen tons for each five-year period. Similar
results were secured in the use of commercial fertilizers.

The above results also show that rotation without fertilization
does not permit so rapid a reduction in the yield of corn as con-
tinuous cropping. Moreover, rotation gives greater returns from
manure and commercial fertilizers than a one-crop system.

In the same series of experiments it is interesting to note how
rotation increased the yield of winter wheat.

A SIMPLE CHANGE OF CROPS NOT ALWAYS BENEFICIAL 271

Crop Rotation Increased the Yield of Winter Wheat*

Cropping system

Fertiliser treatment

Average
annual yield
per acre for
period
1894-1898

Average
annual yield
for the third
5-year period,
1904-1908

Decrease and
increase in
15 years
(per cent)

Wheat continuously
Wheat in 5-year
rotation
Wheat continuously

Wheat in 5-year
rotation

No treatment

No treatment
Fertilizers
(mixed) f
Fertilizers

(mixed )t

Bushels
10.08

9.28
19.78
20.53

Bushels

6.19
13.66
17.41
33.10

38 decrease
47 increase§
12 decrease
61 increase

* Ohio Experiment Station bulletin 231, 1911.

t One hundred sixty pounds each of acid phosphate and nitrate of soda, and 100 pounds
of muriate of potash applied annually to the wheat crop.

t Fertilizers applied 3 times in each 5-year period — 80 pounds each of acid phosphate
and muriate of potash to each corn and oat crop, and each wheat crop received the same
treatment as given each crop of wheat in continuous culture.

§ It cannot be assumed that this increase on the unfertilized plot will con-
tinue indefinitely.

Under the conditions of this experiment) rotation of crops is
much more favorable to the growing of winter wheat than continu-
ous cropping when yield and economy of production are considered.

Rotation Can Not Take the Place of Fertilizers.— Though
a proper rotation is a most important farm practice to aid in main-
taining and increasing soil fertility, yet it cannot take the place
of manure and commercial fertilizers. Whenever crop rotation
without fertilization increases the productivity of a soil, it is only
temporary; because when the yields are thus increased, the draft
upon the plant-food elements becomes greater, and this tends
towards more rapid soil depletion. It becomes more urgent,
therefore, to practice rational fertilization in order to secure the
best results from rotations. The results in the tables, pages 270
and 271 emphasize this fact.

Rotation Only One of Several Factors in Maintaining Fertility.
—It is well to keep in mind the several factors involved in main-
taining soil fertility, which are: (a) Thorough drainage; (6) proper
tillage; (c) crop rotation; (d) liming; (e) a rational use of manure
and cojrimercial fertilizers, and (/) green manuring.

A Simple Change of Crops Not Always Beneficial. — Farmers
have observed, and soil investigators have demonstrated, that a
simple change of crops may not always prove beneficial. In some
sections farmers experience unsatisfactory corn crops when grown
after sugar beets. The North Dakota Station has found that on

272 CROP ROTATION

the typical soil of the Red River Valley, spring wheat yields best
when preceded by corn, potatoes, mangels, peas and clover; and
when preceded by oats, barley, spring rye and flax, the yield was
practically the same as when wheat was grown continuously.

Winter wheat does well after early potatoes, clover, alfalfa,
soybeans and pasture. Onions do best after onions, except when
certain bisects or diseases become injurious. Corn usually suc-
ceeds best after clover, alfalfa and pasture. Oats on rich lands
stand up better and yield best when they are grown after such
crops as corn, wheat, barley and cotton. These are but a few illus-
trations to emphasize the importance of considering carefully the -
best combination of crops for rotation, and the place each crop
should occupy in the rotation for best results.

Factors Determining a Good Rotation. — It follows that there
are two factors which determine a good rotation, viz., a proper
combination of crops, and the order in which these crops should
be grown.

Proper Combination of Crops. — In general, the benefits of
rotation can best be attained when the cropping system includes
(a) a cultivated crop, (6) a grain crop, and (c) grass, clover or some
other legume.

The growing of a cultivated crop aids in weed control, and
in many instances improves the physical condition of the soil
and prepares the land for the crop following. Corn, for example,
is often grown two years in succession on blue-grass sod to eradicate
the blue-grass in preparing the land for alfalfa. A cultivated crop
also prepares the ground for grain.

The growing of small grain in the rotation greatly facilitates
the seeding of grass, clover, etc., without losing the use of the land
during the time required for the grass or clover seeding to become
established for use as hay or pasture. In addition to their value
as grain crops, fall-sown grains may serve as catch and cover crops,
and frequently as winter pasture crops, of particular value in
the South.

No rotation can give best results without a legume. Experi-
ments show that crops can be produced most economically only
when clover or some other legume is grown in rotation with them.
In a twenty-year test at the Ohio Station, it was found that the
average cost of the commercial fertilizers per bushel increase in
yield was forty cents for corn, sixty-six cents for oats, and sixty-
nine cents for wheat, when these crops were grown continuously

CROP ROTATION AND SOIL IMPROVEMENT 273

and without clover.1 When these same crops were rotated with
each other and with clover, the cost of the fertilizer averaged only
four to five cents per bushel of increase.

Proper Order of Cropping. — Much depends upon the order in
which crops are grown. Usually cultivated or intertilled crops are
followed by small grains, which in turn, are followed by hay or
pasture. Sod is commonly planted to some cultivated crop.

Aside from this order, it is important to know what cultivated
crop is best to follow a certain other cultivated crop; or when two
grain crops are grown in succession, which one should follow the
other for best results. The growing of deep rooted plants after
shallow feeders has already been suggested as an important con-
sideration. In Central Kansas the growing of alfalfa (where it can
be grown) leaves the ground so dry that it is usually not wise to
grow corn after alfalfa, but rather an early maturing variety of
sorghum instead. On rich bottom lands in this section, where
the moisture supply is usually good, corn may follow the spring
cutting of alfalfa. Other facts concerning the proper sequences
of crops have been mentioned in a preceding paragraph, page 267.

Crop Rotation and Soil Improvement. — Crop rotation alone,
even when clover is included, will not maintain yields, perma-
nently. After awhile the clover fails, and as a result farming fails.
Whenever a cropping system is planned to maintain or increase
crop production it is essential that a definite soil-enriching plan
be established at the same time. In some cases, clover and green-
manuring crops are of the greatest immediate importance to
increase and maintain the nitrogen supply and the organic matter.
This seems to be true in the greater portion of the Great Plains
area. Most soils, however, respond best and are improved the
quickest when a carefully planned cropping system is established
which embraces some definite plan involving the use of lime,
manure, legumes and special fertilizers. These soil-improvement
materials make possible successful crop rotation, and rotation, in
turn, makes possible the most profitable returns from the use of
lime, manure and fertilizers.

It is recognized that a short rotation is usually the most
effective in soil improvement, largely because of the growing of
more clover and the more frequent application of manure and
fertilizers. The advantage of a short rotation in soil improvement
is illustrated in the next table. These results were secured at the

1 The Monthly Bulletin, Ohio Station, June, 1918.
18

274

CROP ROTATION

Ohio Station (Bulletin 282). The experiments are being conducted
on silt loam soils which were depleted when the tests were begun.

A 3-year Rotation Better than a 5-year Rotation in Soil Improvement
(As indicated by the yield of corn)

System of cropping

Soil treatment

Average
yield for
20 years

Average
yield for
17 years

Corn continuously

No treatment

Bushds

15.5

Bushels

Corn continuously

Manure, 5 tons per acre per

year

37.0

Corn in 5-year rotation *
Corn in 3-year rotation f

No treatment
No treatment

29.0

35.2

Corn in 5-year rotation. . .
Corn in 3-year rotation . . .

Manure, 8 tons twice in rota-
tion — to corn and wheat. .
Manure, 8 tons every third
year — on corn

51.8

60.2

* Rotation of corn, oats, wheat, clover, timothy. (Crops grown in order named.)
t Rotation of corn, wheat, clover. (Crops grown in order named.)

It is to be noted that the average yield of the 3-year rota-
tion without any soil treatment is 21.3 per cent greater than that
of the 5-year rotation without manure. With manure, the 3-year
rotation produced an average yield 16.2 per cent greater than
that of the 5-year rotation. This is significant, since both are
considered good rotations.

It is interesting to note that the average yield for the 3-year
rotation without manure is almost as good as that of continuous
cropping wherein five tons of manure are used annually.

SOME PRACTICAL ROTATIONS

Because of the great variety of crops, soil condition, climate,
and of the varied combinations of crops in different systems of
farming, many different kinds of rotations are practiced, some of
which are recognized as standard. A few of these rotations are
given here to show how important crops of the different sections
of the country may be grown with best success. .Most of these
rotations include the use of manure and commercial fertilizers.

Rotations to Increase Organic Matter. — In beginning the
improvement of most depleted soils it is best to practice a rotation
that will increase the soil organic matter. In the Northern states
a 3-year rotation of corn, grain and clover is common. Farther

ROTATIONS FOR THE NORTH CENTRAL STATES 275

south, as in the Central Atlantic States of the Coastal Plain section,
the following rotation is considered a good one for soil improvement :

1. Cowpeas (plowed under), followed by rye (plowed under
about May 1).

2. Cowpeas (cut for hay), followed by crimson clover (sown in
the fall and plowed under about May 1).

3. Corn followed by crimson clover (sown at last cultivation
and plowed under for other crops).

Rotations for the North Central States. — This group of states
comprises Ohio, Indiana, Michigan, Wisconsin, Minnesota, Iowa,
Missouri, Illinois, North Dakota, South Dakota, Nebraska
and Kansas.

The important crops, named in the order of their importance
on the basis of acreage are : Corn, oats, hay, winter wheat, spring
wheat, barley, rye, flax, potatoes, peas, and tobacco.

FIG. 170. — The alfalfa acreage. Fio. 171. — Timothy and clover mixed.

The important legumes and their adaptation are:

Medium red clover — for general use for hay and pasture.
Grows best on soils well supplied with lime.

Alsike clover — adapted for low lands and for acid soils.

Mammoth clover — best for sandy soils and for green-manuring.
Grows best on non-acid soils.

Alfalfa — grows best on well-drained rich uplands, well supplied
with carbonate of lime (Fig. 170).

Soybeans — grow well on soils of slight to medium acidity.

Cowpeas — for southern portion of this section — grow well on
acid soils.

A few common rotations are given, each being lettered. The
crops in the rotation are numbered.

A — 1. Corn. 2. Oats, wheat or barley (seeded). 3. Clover.
Some other cultivated crop may take the place of corn. Clover
is commonly mixed with timothy (Fig. 171) and other grasses
to produce hay or pasture for the fourth year.

276

CROP ROTATION

B — 1. Corn (in which some green-manuring crop may be sown).

2. Oats (if prairie soil, oats disked in on corn land; seeded). 3.
Clover — plowed in fall and sown to winter wheat. 4. Winter
wheat (Fig. 172) (seeded with mammoth clover to plow under,
or if soil has "tight" or heavy clay subsoil, sweet clover is better).

C — 1. Corn for grain or silage. 2. Soybeans for hay or seed.
(If soil needs organic matter this crop may be plowed under.) 3.
Oats (Fig. 173) or barley (seeded to clover). 4. Clover. 5. Winter
wheat (seeded to mammoth clover for green-manuring) .

This rotation (C) is especially well adapted for loams
and sandy loams.

D — 1. Corn. 2. Oats (seeded to mammoth clover to plow
under), winter wheat sown in the fall or spring wheat in the spring.

3. Wheat (seeded to clover or clover and mixed grasses) . 4. Clover
(often followed by pasture the fifth year) .

EACH DOT
9tPHES£NT
10000 ACRES

FIQ. 172. — Winter wheat acreage.

Fio. 173. — Spring oats acreage.

This rotation (D) proves very successful when soybeans,
instead of oats, are grown the second year, as: 1. Corn . 2. Soy-
beans. 3. Wheat (seeded to clover). 4. Clover.

E— 1. Corn. 2. Flax. 3. Wheat. 4. Clover. 5. Pasture.

F— 1. Alfalfa (five to eight years). 2. Potatoes. 3. Flax.
4. Corn. 5. Wheat.

G — 1. Alfalfa (three to four years). 2. Corn. 3. Grain.
4. Clover.

H — 1. Clover. 2. Potatoes or corn. 3. Rye (seeded to mam-
moth clover).

I — 1. Rye (seeded to mammoth clover). 2. Clover. 3. Corn
(rye in corn for green-manuring). 4. Soybeans (rye sown in fall).

Rotations (H) and (I) are especially good in sand management.

J — 1. Barley (seeded to clover). 2. Field peas. 3. Winter
wheat. 4. Clover. 5. Corn.

K— 1. Tobacco (Fig. 174). 2. Tobacco. 3. Winter wheat
or barley. 4. Clover. Corn may be grown the second year, or
follow the second tobacco crop.

ROTATIONS IN THE NORTH ATLANTIC STATES 277

L — In the spring-wheat section (Fig. 175), the following rota-
tion has been recommended: 1. Spring wheat (three years). 2.
Clover (one year). 3. Corn (one year).

FIG. 174. — Tobacco acreage.

FIG. 175.^— Where spring wheat grows best.

FIG. 176.— Kafir and milo acre-
age.

Rotations for Dry-Land Farming. — (Great Plains area):

Important Crops. — Winter wheat, spring wheat, oats, corn,
barley, hay, rye, kafir corn (Fig. 176), broom corn, sorghum
and potatoes.

Important Legumes. — Alfalfa, red
clover, soybeans, vetch, peas and cowpeas.

Rotations. — Little information exists
on crop rotation for dry-land farming,
since only recently has this subject been
given any attention in the West. The
following are some of the best rotations
at present:

A — 1. Corn. 2. Winter or spring wheat. 3. Oats.

B— 1. Barley. 2. Oats. 3. Corn.

C — 1. Summer fallow. 2. Winter wheat. 3. Oats.

D— l.Corn. 2. Corn. 3. Oats or wheat. 4. Wheat. 5. Clover.

In sections where medium red clover and corn cannot be grown,
cowpeas may be substituted for the clover in rotation (D), and
kafir corn for the corn.

E — 1. Alfalfa (six to eight years). 2. Corn (one year). 3.
Oats, barley or winter wheat (one year) . 4. Winter wheat (three
years). 5. Kafir corn or sorghum. If alfalfa leaves the ground
very dry, an early variety of sorghum is best to follow the
alfalfa. For sections in which the rainfall is especially scant
the rotation should include summer fallow at least every third or
fourth year.

Rotations in the North Atlantic States. — This group of states
includes Maine, New Hampshire, Vermont, Massachusetts, Rhode
Island, Connecticut, New York, New Jersey and Pennsylvania.

278

CROP ROTATION

Important Crops. — Hay, oats, corn, winter wheat (Fig. 172),
potatoes (Fig. 177), buckwheat, rye, peas, barley, and tobacco.

Important Legumes. — Red clover, alsike clover, mammoth
clover, white clover, alfalfa, and peas (Fig. 178).

Typical Rotations. — A — 1. Clover or pasture. 2. Corn. 3.
Oats and peas. 4. Rye (seeded).

B — 1. Corn for grain. 2. Corn for silage. 3. Oats and peas
(seeded down to clover and timothy after harvest). 4. Hay.

In rotation (B) the oats and peas mixture may be omitted, and
the clover and timothy is then seeded in the corn the second year
at the last cultivation. Rye instead of oats and peas is often grown
the third year in such a rotation as this.

C — 1. Corn. 2. Potatoes (autumn rye). 3. Rye (seeded to
clover). 4. Clover or pasture.

FIG. 177. — Late potato acreage.

FIG. 178. — Acreage of green peas.

D — 1. Potatoes (rye sown in autumn). 2. Rye (seeded to
mammoth clover for green-manuring).

This two-year rotation (D) is common in sections where
potato raising is the main business.

E — 1. Corn (rye as cover crop). 2. Tobacco. 3. Wheat or
oats (seeded to clover and timothy) . 4. Hay.

F — 1. Tobacco (Fig. 174). 2. Oats (seeded to clover to plow
under). 3. Winter wheat (seeded) . 4. Clover.

Rotations in South Atlantic States. — Delaware, Maryland,
District of Columbia, Virginia, West Virginia, North Carolina,
South Carolina, Georgia and Florida are included in this group.

Important Crops. — Northern portion: Corn, winter wheat,
hay, oats, tobacco, potatoes, rye, buckwheat and cotton.

Southern portion: Cotton, corn, oats, winter wheat, hay,
tobacco, sweet potatoes, potatoes, rye and rice.

Important Legumes. — Cowpeas, crimson clover, soybeans,
vetches, red clover, velvet beans, alfalfa, and alsike clover.

Some Practical Rotations. — A — 1. Corn (crimson clover sown

ROTATIONS IN THE SOUTH CENTRAL STATES

279

in corn in late summer). 2. Clover (volunteer crop plowed under
in autumn). 3. Winter wheat (seeded to clover and timothy).
4. Hay.

B — 1. Corn (winter wheat sown in the fall). 2. Winter wheat
(cowpeas for green-manuring). 3. Winter wheat (clover). 4.
Hay or pasture.

C— 1. Tobacco. 2. Winter wheat (clover). 3. Clover. 4.
Corn with cowpeas.

D — 1. Corn with cowpeas (winter oats). 2. Oats (clover).
3. Clover. 4. Potatoes (a green-manuring crop sown).

E — 1. Cotton (vetch for winter cover crop or cowpeas). 2.
Corn with cowpeas between rows. 3. Peanuts.

For the third year in this rotation (E) oats and vetch may be
grown for a winter crop and cowpeas for the summer crop.

FIG. 179. — The South is for cotton.

FIG. 180. — Where corn is grown.

F — 1. Cotton. 2. Oats and vetch; cowpeas. 3. Cotton;
vetch for winter cover crop. 4. Corn, with cowpeas between rows.

Rotations in the South Central States. — This group of states
includes Kentucky, Tennessee, Alabama, Mississippi, Louisiana,
Texas, Oklahoma and Arkansas.

Important Crops. — These are named in the order of their impor-
tance on the basis of acreage: Cotton (Fig. 179), corn, oats, winter
wheat, hay, rice, tobacco (Fig. 174), sweet potatoes, sugar cane,
rye and barley.

Important Legumes. — Japan clover (lespedeza), cowpeas, velvet
bean, crimson clover, vetches, soybeans, medium red clover,
alfalfa, and alsike clover.

Rotations. — A — 1. Corn (Fig. 180) (cowpeas sown at last
cultivation and plowed under). 2. Oats or rye (stubble plowed in
summer, followed by cowpeas for feed) . 3% Cotton (cowpeas, vetch
or crimson clover sown between rows).

B — 1. Cotton (cotton stalks plowed under early and winter
wheat sown). 2. Wheat, followed by cowpeas or soybeans for

280 CROP ROTATION

hay. 3. Corn and velvet beans (beans and corn stalks pastured
and turned in early spring for cotton).

C — 1. Corn with cowpeas (crimson clover for cover crop).
2. Soybeans or cowpeas (winter wheat sown in autumn). 3.
Wheat (clover). 4. Clover.

D — 1. Corn with cowpeas. 2. Cotton (cowpeas or clover).
E--1. Tobacco (rye for cover crop). 2. Corn. 3. Winter
wheat (seeded). 4. Blue grass (two years).

F — 1. Rice. 2. Rice. 3. Rice. 4. Fallow. 5. Corn and cowpeas.
G — 1. Sugar cane. 2. Sugar cane. 3. Sugar cane. 4. Corn
(cowpeas for green-manuring).

Rotation for the Pacific States. — Important Crops. — Hay,
wheat, barley, oats, sugar beets, potatoes, corn and rye.

Legumes. — Vetches, clovers, alfalfa
and peas.

Some Common Rotations. — A — 1.
Clover. 2. Pasture. 3. Corn for silage.
4. Oats. 5. Wheat (seeded).

B—l. Winter wheat. 2. Oats (vetch).
3. Vetch for hay. 4. Wheat (vetch for

ACREAGE 1909

S8R8S

FIO. 181. — where most of the cover and green-manuring crop).

sugar beets are grown. /-\ 1 T» i / i L i \

C — 1. Barley (clover or vetch).
2. Peas (fall wheat). 3. Winter wheat (clover). 4. Kafir corn.

D— 1. Sugar beets (Fig. 181) (winter vetch). 2. Vetch crop
plowed under, potatoes. 3. Barley (may be followed by alfalfa).

Rotations for Truck Farming and Vegetable Growing. — Rota-
tions for truck farming and gardening have not been definitely
determined. It is generally recognized that truck crops and
vegetables are grown most successfully in rotation with clover or
some other legume. In general, root crops should follow non-root
crops, and legumes should follow non-legumes. Crops such as
cabbage and sugar beets are best grown in rotation with common
field crops. Wheat-clover-melons, or wheat-clover-corn-melons,
are rotations well adapted for melons where wheat may be grown.
Corn-cowpeas-muskmelons (heavily manured) is a rotation recom-
mended for muskmelons. Some Eastern truck growers grow sweet
corn and cabbage, followed by grain, then clover.

In vegetable gardening particular attention should be given
to succession4 and rotation of crops. Through succession of crops

4 In gardening, succession of crops means following one crop with another
of the same season, while rotation means changing the crop on a given piece
in land from season to season.

ROTATIONS FOR TRUCK FARMING

281

the land may be utilized all the time. As soon as one vegetable
matures or is used another one should be planted in the same space.
For example: early peas may be folio wed by celery; early cabbage

IACM DOT
DCPMMNTS
MOO/KM)

JSS3Z.

MACKS

Fia. 182. — Where beans are grown. Fio. 183. — Tomato acreage.

or potatoes by late beans or corn; early beans may be followed by
cabbage or lettuce, etc. Whenever it is not practicable to plant
another vegetable, the land should be planted to some green-
manuring crop.

f.

FIG. 184. — Cabbages are grown"
generally.

Fio. 185. — Where onions are
produced.

Rotation of crops is as important in growing vegetables as
in growing field crops, and the same principles concerning rotation
should be applied. In general, legumes such as beans and peas
should be followed by root crops like beets, carrots, etc. Crops

FIG. 186. — Where watermelons grow.

FIG. 187. — Celery acreage.

of the mustard family (cabbage, turnips, radish, etc.) should not
follow one another. It is usually advisable to grow foliage crops
like cabbage, kale and spinach after root crops (potatoes, beets,
parsnips, carrots, etc.) or after those grown for fruit (tomatoes,
peppers, melons, etc.). (Figs. 182, 183, 184, 185, 186 and 187).

282 CROP ROTATION

Local Rotations. — Through members of the class make a survey of a
number of farms and determine just what rotations are practiced. Study
each as to the problems of soil maintenance, weeds, insects, diseases, tillage,
income, etc.

Rotation projects may be started to solve one or several of these problems.
Select the problems of economic importance in the region, and conduct such
rotation of crops as to help solve the most difficult problems.

QUESTIONS

1. What is meant by crop rotation? Illustrate.

2. Distinguish between " fixed" and "definite" rotations. Illustrate. Which

of these is the more common? Why?

3. What is meant by "one crop system ?

4. What is the prime object of crop rotation? How is this brought about?

5. Explain how crop rotation may control certain insects and plant diseases.

Give illustrations.

6. How may crop rotation affect the supply of soil organic matter?

7. Tell how a good rotation affects tilth. Illustrate.

8. Discuss rotation in relation to the conservation of fertilizing elements.

9. In what way may rotation be advantageous in liming and in fertilization?

10. In what way is rotation an aid hi weed control?

11. Discuss the effect of a good rotation on soil fertility, (a) As a factor in

maintaining fertility. (6) As a factor in increasing fertility.

12. Can crop rotation in itself maintain fertility or take the place of fertil-

izers? Explain.

13. What are the factors to be considered in maintaining soil fertility?

14. Are the beneficial effects of rotation due simply to a change of crops?

15. Name and discuss the factors determining a good rotation.

16. Tell of the importance of a good rotation in soil improvement. In this

respect, what are the advantages of a short rotation? What important
factor should be considered in planning a rotation for soil improvement?

17. Name in the order of their importance the crops grown in your state, and

give some practical rotations in which these crops may be grown.

18. Name the 'States which lead in the growing of the following crops — corn,

cotton, winter wheat, late potatoes, spring oats, spring wheat, sugar
beets, tobacco, alfalfa and green peas.

19. What are some of the points to bear in mind in planning rotations for

truck farming and vegetable growing?

20. For an outline summary of this chapter see table of contents.

CHAPTER XVI

SOIL EROSION

Soil Erosion a Serious Problem. — Soil erosion is commonly
understood to mean the washing away of soil by water. On
comparatively level areas this problem is not of much importance.
In general, however, it has become most serious. Hundreds of
thousands of acres of farm lands in the United States have rolling
topography, and because of neglect in proper management, im-
mense soil losses have occurred through hillside washing in every
state of the Union and in almost every county of every state. It
has been estimated that in the United States 4,000,000 acres of
farm lands have already been ruined by soil erosion, and nearly
twice as much more greatly damaged. This loss in terms of dollars
amounts to millions annually.

Injuries Resulting From Erosion. — Land ruin is the most
serious effect of soil erosion. Other injuries are: Much of the soil
reserve of plant-food elements is washed away; much damage
is done to irrigation; water power is lost; it interferes with naviga-
tion; and it interferes in farm management (Fig. 188).

The loss of plant- food elements caused by erosion is due to the
removal of organic matter and the fine soil particles. This is
clearly shown in the following analyses of two soils collected on
the same farm — one sample was collected from the hilltop and the
other from the cropped flat, or "creek bottom," below.

Organic Matter

Nitrogen
per cent.

Phosphorus
per cent.

Soil from hilltop
Soil from creek bottom ....

Low
High

0.12
0.25

0.04
0.08

These data show clearly that the soil removed by erosion is
the richest part of the land. This makes the erosion problem all
the more serious. Indeed, it has been estimated that every year
there is in the United States an unnecessary waste from soil erosion
of more than 400,000,000 tons of soil material — an amount greater
than that removed in digging the Panama Canal.1 Much of this

1 United States Department of Agriculture Yearbook, 1916.

283

284

SOIL EROSION

comes from good farming lands. This means a reduction of the
productive power of the country.

Effects on Irrigation. — Soil erosion is one of the serious dangers
that threaten irrigation, as follows: When the blanket of soil is
removed from the mountain sides, there is removed that natural
reservoir which protects the headwaters of the streams. Because
of large amounts of soil brought down by the streams, artificial
reservoirs are filled up. Furthermore, water carrying sediment
decreases the efficiency and increases the cost of maintaining

FIG. 188.— Soil erosion damages fertile fields. Wisconsin Station.)

diversion dams, pipe lines, flumes, and canals. When irrigation
water carries very much mud it injures the crops to which it
is applied.

Effect on Water Power. — Erosion causes a loss of water power
in two ways — the blanket of soil is removed from mountain sides,
thus destroying the natural reservoir for water; and artificial
reservoirs are filled up. In this manner soil erosion interferes
with the steady flow of water so essential in developing successful
water power.

Erosion greatly interferes with navigation, especially on the
inland waterways of the country. In fact, it is largely because
of the bad effects produced by erosion that these waterways have

CLEARING OF STEEP SLOPES 285

not been properly developed. Many rivers formerly navigable
have now become so filled with sediment that they cannot carry
boats of even moderate size. Other rivers have to be dredged
constantly to permit of navigation.

Injures Crop Production. — In crop production, ditches are very
often the cause of greater machinery cost and repairs. Moreover,
a crop cannot be .cared for and harvested most efficiently when
the field is full of ditches, nor can the land be prepared for planting
at as low a cost as when no ditches are present.

CAUSES OF EROSION

Nature's vs. Man's Way. — It is the natural tendency for the
soil to creep down slopes or to be washed away. However, when
the ground is covered with leaf mold, grass, or other vegetation,
the creeping is comparatively slow. During rains, especially in
forests, the water is intercepted by the trees and drips down
quietly without causing any beating effect on the soil. Moreover,
the layer of leaf mold in the forest, grass in the open, and the organic
matter in the soil permit the rain to soak gradually into the ground
and not wash over it. In this way a steady source of water is pro-
vided the springs and streams. This accounts for the clear, steady
streams which come from virgin forests; and it also explains why
the pioneer farmers found so many more springs which flowed the
year round than may be found today.

The development of our lands for agriculture marks the begin-
ning of excessive erosion in this country. It was quite necessary,
to be sure, that the primeval forests over the greater portion of
the country should be cleared away to give place for corn and
grain, but in the doing of it, it was entirely possible to greatly
lessen and even prevent the excessive damage done to the soil.
It has been largely because of man's activities, therefore — activi-
ties which were carried on with but little or no thought to the
future — that this problem of soil erosion is so serious today.

Clearing of Steep Slopes. — The clearing of non-agricultural
lands is one of the main causes of unnecessary erosion. Thousands
of acres on slopes too steep for successful farming should never
have been cleared, but because they were cleared, thousands of
acres have become ruined. Such cleared lands have been cheap.
Settlers moved on to them, and moved off again after they hastened
devastation by improper methods of farming. Many lands should
have been only partially cleared.

286 SOIL EROSION

Fire a Causal Agent. — The effect of fire in its relation to soil
erosion is similar to that of clearing. Fires have burned not only
the tree growth but the leaf mold as well, leaving the ground
exposed to the beating of the rains and thus causing surface run-
off and hence soil washing.

Destructive Lumbering. — Clear cutting of timbered lands has
commonly been practiced even on steep slopes where a part of the
younger growth, at least, should have been allowed to stand.
Fires have been permitted to do much damage, especially on cut-
over areas. Roads were so laid out as to result in serious erosion
and skid tracks were gouged out and left unprotected only to
wash out after every heavy rain.

Overgrazing. — A hillside well grassed is fully protected from
soil washing. During ordinary rains the grass protects the soil
from the beating effect of the falling water, and also causes the
water to soak into the soil and not pass away as surface run-off.
The physical condition of the soil commonly present under a
good grass covering has much to do in facilitating the entrance
of the rain water into the ground. During heavy rains the long
grass blades form a protective mat over which the flood waters
pass with little or no harm to the soil underneath. When rolling
lands are pastured or grazed too severely this protective grass
covering is destroyed and severe erosion results.

KINDS OF EROSION

Gully erosion is characterized by the formation of V-shaped
cuts or ditches. Sometimes these gullies are small, numerous and
more or less parallel to each other. At other times they are few
in number, but deep and broad. Under certain conditions gullies
form which have vertical, cliff-like sides which keep caving in as
the water undermines them. When once started, such gullies
rapidly become deeper, wider and longer with every storm until
they develop into ugly chasms.

Sheet erosion is the washing away of the soil more or less
uniformly over the entire surface without the formation of gullies.
This erosion usually forms on fields of only moderate slope. Every
rain washes away some of the finer particles; but since the process
of washing is usually slow, results are not particularly noticeable.

Landslides. — A landslide is the sliding down of a large quantity
of soil. They are usually caused by the soil becoming saturated
with water and then slipping in a large body from the under-

TILLAGE 287

lying subsoil or rock. Frost action is also responsible for
many landslides.

River-bottom Erosion. — Good valley land is often destroyed,
either by the wearing away of the river banks along the main
channel or by the gouging out of new channels. The Kansas
River flood, of 1903, for example, completely destroyed 10,000
acres of excellent farming land and caused a total loss of at
least $22,000,000.

PREVENTION OF EROSION

Prevention in General. — Since surface run-off is primarily the
cause of soil erosion, its prevention and control depend, in a large
measure, upon the way in which the protective cover of trees,
grass and other vegetation is cared for, and on the way in
which cleared and cultivated lands are handled. There are, of
course, some factors influencing surface run-off that are beyond
the control of man, such as the distribution of the rainfall and the
geological formation. Other factors, like the slope and the character
of the soil, may be modified to a certain extent.

Much can be done to decrease and prevent erosion by prevent-
ing fires from sweeping through forests and over cut-over lands,
by ceasing to overgraze the ranges, and by ceasing to clear steep
slopes for farming. Since so many lands devoted to agriculture
are rolling, erosion becomes a common agricultural problem.
The following discussion concerns the control of erosion in farming.

Drainage and Organic Matter. — Surface run-off may be
lessened by good underdrainage. In this way the capacity of a
soil for taking in water is increased. Often the thorough drainage
of a large body of peat greatly lessens the amount of flood water
that will flow away because the greater portion, if not all, of the
rainfall would be absorbed by the soil.

When the organic matter of any heavy soil is increased the
soil becomes more open and crummy in structure, thus increasing
its water-absorbing capacity. This also results in decreasing
the surface run-off.

Tillage. — Plowing loosens the soil and this allows the rain
water to soak more readily into the ground. In this manner deep
hillside plowing of a heavy soil especially lessens erosion to a
considerable extent.

When a hillside is plowed, it should be done at right angles
to the slope; and all cultivated crops should be planted so that

288

SOIL EROSION

cultivation can be done around or across the slope rather than with
the slope. When furrows run up and down the hill washing is
greatly increased. This precaution may well be observed in sowing-
grains as well.

Crops May be Alternated on Hillsides. — On long slopes it is
good practice to lay out the field into comparatively long and
narrow strips, and crop them alternately with corn, grain and
grass. In this manner the distance down hill through which the
accumulation of water may occur is shortened, thus greatly pre-
venting the formation of tiny streams.

is through fields which serve as surface runs should be kept sodded.
(Iowa Station.)

Grassing and Cover Crops. — On many steep slopes it is well
to keep the ground well protected by a good grass cover. Depres-
sions which serve as surface-runs should be kept sodded. The
growing of winter cover crops like rye and clover should be encour-
aged. The roots of such crops help to bind the soil and the vegeta-
tive growth protects it (Fig. 189).

Terracing. — Terracing is the most effective method of prevent-
ing soil washing, and it is doubly effective when other methods
of controlling erosion are practiced in connection with it. Terrac-
ing consists primarily in reducing the slope over which the water
moves, or in stopping the flow of water down the slope by forming
balks or breaks which gradually rise into banks separated by
belts of plowland.

TERRACING

289

There are two distinct types of terraces — the bench terrace
and the ridge terrace (Figs. 190 and 191). A field of bench ter-
races resembles a series of benches, while ridge terraces are simply

FIG. 190. — Bench terraces. (U. S. D. A.)

ridges of earth thrown up across the slope of a hillside. The former
is essentially steep-land terracing, -and the latter is for moder-
ate slopes.

FIG. 191.— Ridge terracea. (U. S. D. A.)

In starting bench terraces it is best to locate the position of
the balks on contour lines at regular intervals, and begin by
throwing a furrow upslope and another downward. The balks
thus started should be seeded to grass and kept sodded or planted
to shrubs. The subsequent plowing on each belt of plowland
should be with a reversible hillside plow, throwing the earth down-
ward. The crop rows, too, should run on the contour lines. In
time the balks will become' steeply sloping banks fixed by the
19

290 SOIL EROSION

strength of the sod or the hold of the bushes that may be planted
on the balks, while the belts of plowland become level, or the slope
of the benches is slightly reversed. When the benches become
level, it is necessary to maintain only small shoulders about one-
half a foot high at their outer edges.

Bench terraces should have no fall along the direction of their
length. The level of the benches may be maintained or their
slope regulated by plowing — by turning the furrow slices inward
or outward as conditions may require.

In ridge terracing, the ridges are often cropped, or the field
is planted and cultivated as if no ridges were present. In either
bench or ridge terracing, the rain water that falls on a belt of
plowland is collected and held above the lower terrace until it
evaporates, sinks into the soil or finds its way slowly to an outlet
at the ends of the terraces.2

Terracing is most commonly practiced in the Southern states.

STOPPING WASHING AND RECLAIMING ERODED LANDS

In stopping washes and in reclaiming eroded lands, it is neces-
sary to make use of all the methods employed in prevention.
Aside from these there are many other methods employed in stop-
ping the advance of ditches and in filling gullies.

Reforesting. — Most frequently lands which cannot be used for
farming because of excessive erosion must be reforested in order
to be reclaimed. Trees should be planted thickly in the mouths
of, and as far up, the gullies as possible.

Otiier Measures. — Straw or similar material is usually of much
help in stopping or filling small gullies. Sometimes washes may be
stopped by dragging in some dirt and sowing sorghum thickly.
Often ditches may be filled with straw and debris, and dirt plowed
in on top and seeded with grass, sorghum or grass. Brush, logs,
stumps and stones are excellent materials to throw into gullies
(Fig. 192). Such material should be well anchored to prevent its
being carried away. Many ditches have been completely filled in
this manner. Sometimes dams of wire, mesh, boards, brush and
reinforced concrete are quite satisfactory for certain locations in
preventing further erosion, or in reclamation. Usually such dams
will gradually allow the gully above to fill with sediment (Figs.
192 and 193). The planting of willows or bushes along the edges
of a gully is often effective in stopping further erosion.

2 United States Farmers' Bulletin 997.

OTHER MEASURES

—A stone dam is effective in filling gullies. (Iowa Station.)

FIG. 193. — Filling a bad gully by means of dams. (Iowa Station.)

292 SOIL EROSION

Field Study. — Observe injury due to soil by erosion. Suggest prevention
in particular cases.

Projects in reclaiming eroded land should be conducted. These may
include any or all of the methods suggested in the study of this chapter.

Other projects in preventing erosion should include terracing, grassing, etc.

QUESTIONS

1. To what extent is soil erosion a serious problem?

2. Discuss the injuries resulting from soil erosion.

3. Under natural conditions how is soil washing checked or prevented?

4. Explain why the streams from virgin forests are clear and steady.

5. What marks the beginning of excessive erosion in this country?

6. Discuss the clearing of steep slopes in relation to soil erosion.

7. Discuss the results of destructive lumbering and overgrazing.

8. Distinguish between gully and sheet erosion.

9. What are landslides? What causes them?

10. Describe river-bottom erosion.

11. Upon what depends, in a large measure, the prevention and control of

soil erosion? Name other factors involved.

12. Discuss drainage and soil organic matter in relation to the control of

erosion in farming.

13. What constitutes proper tillage and cropping on slopes subject to washing?

14. What is terracing as applied to soil management?

15. What are the two important methods of terracing? Describe each.

16. Mention some ways in which gullying may be stopped and eroded

lands reclaimed.

17. What examples have you seen?

CHAPTER XVII

THE MANAGEMENT OF MARSH LANDS

IN the preceding chapters are discussed the fundamental
principles governing soil management. Soils that are naturally
productive, particularly loams and silt loams, are not difficult to
manage. Their fertility may be easily maintained if due con-
sideration be given proper tillage, crop rotation, and the use of
lime, -manure and special fertilizers. Some soils, however, differ
so widely in their characteristics from ordinary soils that their
improvement and management require special attention. These
include marsh and swamp soils, sands, clays and depleted silt
loams. In this and the following two chapters, these soils are
discussed as regards their characteristics, improvement and the
maintenance of their fertility.

Three Kinds of Marsh and Swamp Soils. — In general, there
are three kinds of marsh and swamp soils, as follows:

((a) Maybe shallow (6 to 18 inches), or deep (10 to

20 feet)

1 Peat Soils ' ^) May be underlaid by various materials

' ' He) May be raw or well decomposed

(d) May be reddish brown to black in color
((e) May be acid or non-acid

('(a) May be underlaid by various materials
(6) They are heavier than peat soils
(c) May be acid or non-acid

3. Marsh Border Soils!
(grades into and
borders the higher

(6) Usually shallow and black in color
(c) Usually have a blue or mottled clay or sand
subsoil

(d) May be acid or non-acid

Peat and muck are special types of soils. The " marsh border"
soils grade into muck or peat on the one hand and upland on the
other. With the marsh border soils are also grouped the poorly
drained, dark colored soils found along streams and in depressions
on upland. The marsh border soils include many types. In lime-
stone sections they are named Clyde silt loam, Clyde sandy loam,
etc. In sandstone sections they are called Dunning sand, Dunning
clay loam, etc. In sections in which the country rocks are granitic
they are designated as Whitman sandy loam, Whitman loam, etc.
When well drained these soils are usually highly productive.

Advantages in Farming Peat and Muck Soils. — Well-drained

293

294

THE MANAGEMENT OF MARSH LANDS

peat and muck soils can be made productive and profitable. In
fact, there are certain advantages in farming such lands, as: (a)
They are especially well adapted to highly intensive types of farm-
ing such as truck growing and market gardening; (6) they are
easily worked; (c) they respond quickly to proper fertilization,
and (d) they usually supply crops with sufficient moisture during
dry periods.

Most Desirable Muck and Peat. — Muck lands are, as a rule,
more desirable to reclaim than peat. Of the peats, those that are
shallow, well-decomposed and underlaid by clay or silty clay are the
most desirable. Those that are "raw," coarse and deep, or raw and
underlaid by coarse sand, on the other hand, are the least desirable.

Problems in Peat and Muck Management. — In developing
and farming peat and muck lands a number of problems must
receive careful consideration. These problems should be kept
well in mind, together with the manner in which they should be
solved. These are summarized in the following table:

Problems in Peat and Muck Management and Their Solutions

Problems

Solutions

Excessive moisture

Excessive grass, moss or brush

Breaking when tough turf exists

Deficient in potassium and phosphorus
May lack nitrifying organisms
If strongly acid
Too loose seed bed

Subject to late spring and early fall
frosts*

Thorough drainage

Burn (do not burn the peat)

Use heavy 18" or 24"-bottom tractor

plows

Use potash and phosphate fertilizers
Apply manure
Lime the land

Compact through the use of rollers
Select proper crops and varieties;

fertilize properly

* On marshes in the Northern states. See Chapter IX.

Drainage. — It is useless to attempt the growing of crops on
marsh lands without adequate underdrainage. Open ditches alone
often provide just enough drainage to encourage the farmer to
plow and plant, but do not provide the thorough drainage neces-
sary to ensure the crops. Tile in peat should be laid deep to permit
of deep drainage and to allow for the shrinkage and the settling
of the soil. The lines of tile should be given sufficient fall to permit
them to carry off the water. All springs or water-bearing sub-
strata should be located and tapped with lines of tile. The marsh
zone bordering the high land should be especially well drained,
since this is often the wettest portion of the marsh.

CLEARING AND BREAKING

295

Clearing and Breaking. — When peat and muck lands are
covered with tree growth, the problem of clearing and removing
the stumps is comparatively simple, since the stumps are usually
shallow rooted and the soil is light and loose.1 The cost of clearing
varies from fifteen to thirty dollars per acre, and sometimes as
high as seventy-five to one hundred dollars per acre.

Rank grass, sphagnum moss and brush can best be eliminated
through burning. The most desirable time to accomplish this is

FIG. 194. — Two twenty-four-inch bottom plows turning tough marsh turf. (Wisconsin

Station.)

when the rubbish is dry but the soil wet. This is usually done dur-
ing late spring and early summer. Peat should never be allowed
to burn except when there is a surface layer of loose, spongy, raw
peat. In such a case conditions should be controlled to prevent the
burning of the lower stratum. Should peat soil catch fire, the best
method of putting it out, unless soaking rains come, is to dig an
open trench around the fire down to moist or wet earth and let
it burn itself out.

Wild turf on marshes is usually very tough and difficult to break.
The use of heavy, wide-bottomed breaking plows gives best results

1 When peat and muck lands supporting tree growth are drained by good
open ditches, the trees soon die. It is desirable to leave the open ditches
three to four years to allow for the settling of the peat. The ditches are then
cleaned out and the tile laid. During the settling period the trees may be cut
and the stumps pulled.

296

THE MANAGEMENT OF MARSH LANDS

(Fig. 194). Summer and early fall breaking is advisable. Subse-
quent plowing may be done by the use of the ordinary plow.

FIG. 195. — "Sticking " corn immediately after burning. Soil about eighty percent organic
matter. (North Carolina.)

FIG. 196. — " Stuck " corn on burned-over land. (North Carolina.)

Some peat and muck lands, as in eastern Carolinas, are covered
with a thick growth of brush and trees which fill the soil so full of
tough roots and stumps that breaking is exceedingly difficult or
impossible. In such cases the brush is cut and burned and corn
planted without any attempt at breaking (Fig. 195 and 196).

FERTILIZER NEEDS 297

During this initial cropping the roots rot, thus permitting subse-
quent clearing and cultivation.

Frequently marsh lands become very boggy largely as a result
of pasturing while the land is still too wet to cultivate. These
bogs add to the difficulties of breaking. When they are cut off
and cut to pieces, breaking is much facilitated (Fig. 197).

Preparing the Breaking for Planting. — Tough, turf breakings
should be thoroughly harrowed. A cutaway-disk harrow is an
excellent machine to use (Fig. 90). The use of a tractor in pre-

Fia. 197. — A bog cutter. Note the cutting blade (A) extending from runner to runner.

paring the new seed bed is especially good, because its weight
firms the soil and presses the furrow slices down so that good con-
tact is made with the subsoil.

Fertilizer Needs. — Chemical analyses show that peat and
muck soils, in general, contain comparatively small amounts of
potassium and phosphorus. Furthermore, experience and field
tests have clearly demonstrated that potash and phosphate fertil-
izers and manure are second in importance to thorough drainage in
determining crop production on these soils.

Peat and muclc soils vary in their fertilizer needs. Some will
produce fair to good crops for a year or two, after which the yields
diminish rapidly unless the land is fertilized. Other marsh soils
are so deficient in potassium that they fail entirely to produce

298

THE MANAGEMENT OF MARSH LANDS

crops such as corn, even the first year, without manure or fertilizers.
Potash fertilizers give the greatest returns on most marshes,
paticularly those not strongly acid (Fig. 198). Soils showing
an apparent need of potash fertilizers only, eventually need phos-
phates, particularly those on which no manure is used. Acid
marshes usually require both potash and phosphate fertilizers, the
potash being often a secondary need. Frequently a phosphate

FIG. 192.

1 0

N

FIG. 193.

FIG. 198. — This peat soil responds particularly to potash treatment. O, no treatment;
N, nitrogen; P, phosphate; K, potash; KP, potash and phosphate.

FIG. 199. — This peat soil responded readily to phosphate fertilizer, but best to phos-
phate and potash. O, no treatment; N, nitrogen; P, phosphate; K, potash; PK, mixture of
phosphate and potash fertilizers.

fertilizer, when used alone, gives no increase in yield, but when
used in conjunction with a potash fertilizer it increases the yield
as compared to that secured from the use of potash alone (Fig. 199).
Frequently muck or peat underlaid by silty clay, or clay at a
depth of about twelve or fifteen inches, shows a marked need of
potash fertilizer for a few years, but after that this need of potash
partially or entirely disappears. This is because the settling of the

CHOICE OF POTASH AND PHOSPHATES 299

soil causes considerable of the subsoil, which contains an abun-
dance of mineral elements, to become mixed with the soil through
plowing and harrowing.

Nitrogen is present in all muck and peat soils in abundance.
For intensive crops like onions, cabbage and celery, fertilizers
containing nitrogen seem to be profitable, especially on new lands.

Choice of Potash and Phosphates ; Their Application. — Muriate
of potash is most commonly used. Sulfate of potash, a higher-
priced material, is thought by some to produce better quality in
crops like potatoes and onions, but this claim has not been verified.
On soils not previously fertilized, the usual application of muriate
or sulfate of potash consists of about 100 pounds per acre for grass
and small grains, 250 to 300 pounds per acre for corn and potatoes,
and about 400 pounds per acre for sugar beets, onions, etc. When
grown in rotation, the hay is not fertilized since it receives the
residual effect of previous applications.

Of the phosphate fertilizers, acid phosphate is most commonly
used. On soils requiring phosphorus as a secondary need, initial
applications may be made at the rate of 200 pounds per acre for
small grains, and 400 to 600 per acre for corn and truck crops,
respectively. Soils especially in need of phosphorus should be
given special phosphate treatments.

These fertilizers may be mixed and applied at any time. For
general soil improvement broadcast application is recommended.
It is best to mix the fertilizers with the soil through harrowing.
Subsequent applications may be made in somewhat less amounts,
especially when manure is used.

It is more economical to buy muriate of potash and acid phos-
phate separately and mix them on the farm. A desirable mixture
for general use is obtained when these two fertilizers are mixed
in equal proportions.

Rock phosphate applied directly to muck and peat and thor-
oughly mixed in the soil sometimes gives excellent results
(Fig. 200).

Large amounts of mixed commercial fertilizers are used on
marsh lands'. Applications vary from 200 to 3QO pounds or more
per acre for crops like grain, and 500 to 1500 pounds or more per
acre for corn and truck crops, respectively.

On lands previously cropped and fertilized, the application of
commercial fertilizers in the hill or drill for crops like corn gives
excellent results, especially when a mixture of muriate of potash

300 THE MANAGEMENT OF MARSH LANDS

and acid phosphate is used. In a six-year test on a peat marsh in
Wisconsin2 an annual application of 125 pounds of a mixture of
muriate of potash and acid phosphate, mixed in equal proportions,
and applied in the drill for corn gave better average results than
the use of a mixture of 400 pounds of muriate of potash and 600
pounds of acid phosphate applied once in the first three-year
period of the experiment, and 200 pounds of each of the two
fertilizers applied once in the second three-year period.

The favorable results secured in applying fertilizers in the drill
through the use of fertilizer attachments have led many truck

FIG. 200. — Rock phosphate prevented lodging of oats on this peat (1918). To right,
1000 pounds rock phosphate and 200 pounds potash applied per acre in 1913. To left,
200 pounds potash and 400 pounds acid phosphate applied per acre (1913).

growers on marsh lands to make a liberal application of fertilizer
broadcast (either manure or commercial fertilizers) and to follow
with an application of about 132 pounds of a complete fertilizer
in the drill, especially for crops like the sugar beet and cabbage.

Manure on marsh lands may give good results. Many growers
prefer manure to commercial fertilizers for truck crops. For
general crops like" corn and grains, commercial fertilizers are much
more economical (Fig. 132) . When manure is not plentiful its
application to upland soils is preferable and more profitable. If,
on the other hand, manure is plentiful and the uplands have all

2 Peat is well decomposed, averages five feet deep and is thoroughly
drained. Received manure treatment the year before the test began. Corn
was grown each year.

LIMING AND THE NITROGEN PROBLEM 301

been heavily manured, its application on peat or muck may be
advisable. Some truck growers have found potash fertilizers to
be quite necessary to reinforce the manure.

The use of manure greatly increases the weed problem. In case
of corn, weed control can be much facilitated when the crop is
planted in checked rows to permit of more thorough cultivation.
Because of the weed problem, many farmers much prefer the use
of commercial fertilizers entirely, especially for general farm crops.

Wood Ashes Are Valuable. — Unleached wogd ashes applied
at the rate of from one to two tons3 to the acre give most excellent
results on acid mucks and peats, chiefly because of the potash and
carbonate of lime they contain. Results secured through the use
of wood ashes on some acid peats could not be duplicated by any
mixture of commercial fertilizers.

Liming and the Nitrogen Problem. — Even though peat and
muck soils contain nitrogen in abundance, some crops growing on
these soils suffer for want of this element. It may be advisable
at times to apply nitrogen in the form of nitrate of soda as a top-
dressing at the rate of 50 to 100 pounds to the acre to a crop like
onions, when it shows the need of it by turning yellow. This per-
haps explains why mixed fertilizers and manure are much preferred
by truck growers.

A nitrogen deficiency may occur as a result of four conditions,
viz. : (a) The soil may be too cold to favor decay and nitrification ;
(6) decomposition may be too slow because of the nature of the
organic matter; (c) strong acidity may hinder the formation of
available nitrogen; (d) there may be a lack of nitrifying organ-
isms (Chapter XI).

Nitrification in strongly acid soils is greatly promoted through
liming. Finely pulverized limestone or any other finely divided
lime may be used. The use of agricultural lime is particularly
necessary in fitting acid peats or mucks for truck growing. The
addition of lime not only favors nitrification, but it renders the
phosphorus more available as well (Chapter XIII) .

It is thought that the particularly beneficial effect of manure
on many marsh soils is due in part to helpful organisms which
are added with the manure. Horse manure is especially good in
this respect. Peat lands which are pastured a few years before
breaking are much improved both in their physical condition and
in their productive power.

3 When containing 30 to 40 per cent moisture.

302 THE MANAGEMENT OF MARSH LANDS

Unproductive or " Bogus " Spots. — It is common experience
in marsh-land derelopment to find some spots that are difficult
to make productive. These may be alkali spots (p. 44); small
areas lacking adequate, subsurface drainage; the soil may be
exceptionally deficient in potassium ; or they may be unproductive
because of the presence of some poisonous compounds. If given
special attention, these conditions can usually be corrected through
proper drainage and through the use of mineral fertilizers and
agricultural lime.

The Roller Necessary in Marsh-Land Farming. — Much diffi-
culty is experienced in farming peat lands because the soil is so
loose. In order to secure a firm seed bed, it is necessary to use a
roller. Often it is best to roll a field several times. Rolling both
before and after seeding or planting is preferable. Sometimes
desired results can be attained only when the roller is heavily
weighted, or when an extra heavy roller weighing from 3000 to
5000 pounds is used. Smooth rollers are not so satisfactory as
other forms of packers. The use of a tractor in preparing the seed
bed is beneficial in this respect. A firm seed bed warms up better,
and this reduces the danger from frosts.

Hay fields on muck and peat lands may be much benefited
if they are rolled in the spring.

Frost on Marsh Lands. — One of the disadvantages in farming
northern marsh lands is the danger of frosts. On account of later
frosts in the spring and earlier frosts in the fall, the growing season
on such lands is considerably shorter than on the high land in the
same locality. This emphasizes the necessity of considering care-
fully the crops to be grown on the marsh lands in any particular
section. For the more northern marshes root crops, hay, cabbage,
grains and early varieties of corn are recommended.

When frosts occur either hi early or late summer, the injury
to corn is much reduced if the crop is well fertilized. This advances
the corn and seems to enable it to withstand the low temperature
much better than it otherwise could. Applying fertilizer in the
drill is advantageous in this respect (Figs. 201 and 202).

What Crops Best to Grow. — The fact that mucks and well
decomposed peats are most excellent soils for trucking and garden-
ing has led many marsh-land owners to think that these soils are
adapted for intensive crops only. According to the United States
Department of Agriculture, at least 300,000 acres of marsh lands

WHAT CROPS BEST TO GROW

303

FIG. 201. — Corn on peat properly fertilized was not entirely destroyed by frost. (See

Fig. 202.)

FIG. 202. — Corn not fertilized was completely destroyed by frost. Plot about four
rods from that shown in Figure 201.

304

THE MANAGEMENT OF MARSH LANDS

could produce all the cabbage, onions, celery and mint needed by
the whole United States.3 In the eight North Central States4
alone there are 15,000,000 acres of marsh and swamp lands most
of which are capable of being drained and utilized for agricultural
purposes. It is plain, therefore, that all marsh and swamp lands
cannot possibly be utilized for trucking and gardening, but may be
suitably used in growing general farm crops (Fig. 203).

CROPS

ACRES

10 2.0 30 4O 50 60 70

CELERY
ONIONS
CABBAGE
PEPPERMINT
CORN
COMBINATION

s= — - _„

FIQ. 203. — Approximate number of acres on peat land that can be worked by one man in
different crops. (U. S. D. A.)

FIQ. 204. — Farming marsh lands along extensive lines. Four years from swamp. Hogs
in rape. (North Carolina.)

On tough turf breakings buckwheat and flax are commonly
grown to subdue the sod. On pastured marshes, particularly, corn
is frequently grown as the first crop. Crops for marsh lands are
mentioned in the table on next page, together with the advan-
tages and disadvantages in growing them.

3 United States Department of Agriculture Farmers' Bulletin 701.

4 Ohio, Indiana, Michigan, Illinois, Wisconsin, Minnesota, Iowa and
Missouri.

CROPS FOR MARSH LANDS

Crops for Marsh Lands*

305

Crops

Corn

Hay

Pasture

Potatoes

Winter
wheat

Barley
Oats

Rye

Buckwheat
and flax
Cabbage

Onions

Celery

Sugar beets
Peppermint

Hemp

Millet

Soybeans

and

Cowpeas
Alfalfa

Advantages

Good yield and prices; labor
cost low

Yield good; price fair; labor
cost very low

Excellent pasturage; good re-
turns; moisture supply good

Easy to plant, cultivate and
harvest potatoes on muck
and peat

Good yield; price stable; labor
cost low

Usually as profitable as oats

Yield and price fair; labor cost
low; good feed

Good value as feed

Good to subdue tough sod;

easy to grow
Possibility of good income per

acre

High yield and possibility of
very large income per acre

Muck and well-decomposed
peat soils best for celery;
large income per acre

Good yield and returns

Muck and well-decomposed
peat best for peppermint;
possibility for very large in-
come per acre with moderate
amount of labor

Good income per acre

Grows well on marsh soils; can

be sown late
Grow well on muck and peat;

high feeding value

Has been grown on well-
drained muck and peat; ex-
cellent feeding value

Disad vantages

Danger of frost in late spring
and early fall; weeds fre-
quently troublesome

Quality of marsh hay sometimes
poor

Sometimes injured by excessive
heaving during winter

Market discriminates against
"muck " potatoes

Frequently heaves badly in
winter; difficult to get firm
seed bed

Danger of frost in spring and
lodging at harvest time

Danger of frost in spring; fre-
quently lodges badly at har-
vest time

Yield and prices usually low

Danger of frost; subject to
blight on marsh lands

Fluctuation in price; danger of
rotting; large labor require-
ments

Great fluctuations in price;
weeds difficult to control;
large amount of labor re-
quired; insect enemies

Large amount of labor required;
danger of blight and rotting;
price unstable

Requires much labor; quality
lower than upland beets

Demand very limited; fluctua-
tion in price great; expensive
equipment needed

In some sections much skilled
hand labor required because
of lack of proper machinery

Not the best of feed

Inoculation necessary; strongly
acid soils should be limed

Not a dependable crop; winter
kills; requires thorough drain-
age, lime and inoculation

*With special reference to marshes in the Northern states, as regards frost.

20

306 THE MANAGEMENT OF MARSH LANDS

•

Crop Rotation. — Rotation, or at least a change of crops, on
marsh soils is advisable (Chapter XV). Many farmers who spe-
cialize in growing onions, celery, cabbage, etc., much prefer to grow
the same crop continuously on the same land. Little attention is
thus given to minor crops; and when a change of crop is made, it
is only when the principal crop is threatened with some insect or
plant disease.

Some successful truck growers plan the growing of clover and
timothy at frequent intervals. This adds easily decomposable
organic matter (as sod), which aids the liberation of plant-food
elements and improves the physical condition of the soil.

Some good rotations for general or dairy farming are as follows:

A. — Corn (three to four years). Oats or barley. Hay (clover
and timothy).5

B. — Corn (two years). Oats. Hay. Pasture.

C. — 1. Corn (rape sown at last cultivation). 2. Sugar beets.
3. Oats (seeded). 4. Hay (pasture may follow for fifth year).

Corn is often grown two to three years in succession. Some
sow rape at the last cultivation. This is beneficial not only in
furnishing some fall pasture (Fig. 204), but also in firming the soil.
After the original wild sod is subdued, it is often advisable to grow
corn or some other cultivated crop two or three years before grain
is tried. Too thick seeding of grain should be avoided, because
of the danger of lodging which necessarily smothers the seeding
of clover and grass. For this reason it is often advisable to cut
the first oat crop or two for hay to save the seeding. The preven-
tion of lodging depends, in a large measure, on the amount of seed
sown per acre and the use of proper fertilizers. A mixture of alsike
clover, timothy and red-top constitutes the most common grass
seeding for marsh lands. These are usually mixed in about equal
proportions. Medium red clover is sometimes used.

Types of Farming. — Four types of farming may be practiced
on marsh lands, viz., trucking, dairy or stock farming, grain
farming, and combination farming, as trucking and dairying. The
type of farming practiced in any locality depends upon many fac-
tors, important of which are: The adaptation of crops to1 soil and
climate; nearness to markets; availability, cost and seasonal
distribution of labor; and injury from insects and plant diseases.

Trucking is determined largely by the nearness to large centers

6 Alsike clover, timothy and red-top is a common grass or hay mixture
for marsh lands.

LABORATORY EXERCISES 307

of population which offer ready markets. The lack of available
labor in some sections, on dairy and stock farms, and especially
on large tracts, determines, in a large measure, the development of
marsh lands along extensive lines, since one man in general or stock
farming can care for many acres. This is well shown in Figure 203. 6

The growing of general farm crops does not involve so much
risk as in the growing of such crops as onions and celery; moreover,
the profits are .more dependable from year to year. It is also highly
probable that, through a period of years, the average profit in
grain-and-stock farming will be larger than for any special type,
as in celery or onion farming, when similar amounts of capital and
labor are involved.6

Many farms include marsh tracts containing from a few to
many acres. It is common experience that when these tracts are
well drained and properly fertilized they become as profitable as
the best upland.

It is possible to pursue general or stock farming on farms con-
sisting entirely of muck and peat soils. Indeed, many such farms
are already being operated with marked success. These are encour-
aging facts since it is plainly evident that if large areas of marsh
lands are to be utilized for agricultural purposes extensive systems
of farming must be developed.

Field Studies. — 1. Study good systems of marsh management, particu-
larly on successful farms.

2. Examine an undrained marsh and note in particular the wetter por-
tions, and determine the reasons why.

3. On the same area examine the depth and different types of soil. Sketch
a map of the area indicating the streams, types of soil, etc.

Home Projects and Experiments. — To determine the profitable use of
mineral fertilizers on a peat soil.

Procedure. — Lay out at least an acre, or a smaller area, of peat soil and
divide equally into. three strips. To strip No. 1 apply muriate of potash at
the rate of 200 pounds per acre. Strip No. 2 is to receive no treatment. On
strip No. 3 apply a mixture of muriate of potash and acid phosphate at the
rate of 200 pounds of the potash and 300 pounds of acid phosphate per acre.
(Figs. 225, 226, 227, 132, and 221). Keep account of all costs, determine yields,
and compute net profits.

To Compare the Value of Wood Ashes with a Potash Fertilizer. — Pro-
cedure.— In a similar manner as in the previous project, compare the value of
wood ashes with muriate of potash or sulfate of potash. Use corn. Con-
sult text.

To Determine Economy in Using the Proper Fertilizer in the Hill for Corn.
— Procedure. — Mix acid phosphate and muriate of potash in proportion of one
to one. On one strip of peat apply 125 to 135 pounds of this mixture per acre

6 United States Department of Agriculture Farmers' Bulletin 761.

308 THE MANAGEMENT OF MARSH LANDS

for corn with a fertilizer attachment on the planter; on an adjoining area apply
400 pounds of the mixture, broadcast. Drag the fertilizer in before planting.
Plant all the corn at the same time. Keep account of costs, determine yields
and compute profits.

Other projects and experiments may be planned on suitable plots to com-
pare, (a) spring plowing with fall plowing; (6) plowing unojer barnyard
manure with the application of manure as a top dressing and disked in before
planting; (c) plowing of peat with just disking; (rf) the growth and yield of
a crop on well-rolled plot with that on unrolled plot.

QUESTIONS

1. Distinguish between marsh and swamp lands.

2. Describe in general marsh and swamp soils.

3. Can any good be said of muck and peat soils?

4. Tell of the relative value of muck and peat soils for farming.

5. What are the important problems in the development and farming of marsh

and swamp lands? How may these problems be met?

6. What is a common mistake made by marsh-land owners?

7. Discuss in general the drainage of marsh and swamp lands.

8. Discuss the problem of clearing and breaking. In preparing ' the new

seed bed.

9. What are the fertilizer needs of peat and muck soils? How have these

needs been shown?

10. Does the same rule concerning specific fertilizer needs apply to all marsh

and swamp soils? Explain.

11. What choice is to be made of the different fertilizers?

12. How may commercial fertilizers be applied to peats and mucks? Which

method is the best?

13. Discuss the use of manure on peat and muck soils.

14. Where would unleashed wood ashes give best results, on an acid peat

or on a non-acid silt loam? Why?

15. Is it necessary to lime marsh lands?

16. How may manure benefit marsh lands other than through the addition

of fertilizing elements?

17. What can be said of the benefits to be derived in pasturing peaty soils?

18. What may be the nature of unproductive spots on marsh lands? What

remedies should be applied?

19. What important problem arises in farming peat lands due to the physical

characteristics of the soil? Discuss remedies.

20. Discuss the relation of frost to marsh lands. What can the farmer do to

avoid or lessen injury due to frosts?

21. Distinguish between intensive and extensive farming.

22. Are all marsh and swamp lands to be developed and farmed along inten-

sive lines? What are the facts?

23. Name some advantages and disadvantages in growing the following

crops on muck and peat soils: Corn, hay, potatoes, oats, hemp, cabbage,
mint and sugar beets.

24. Is it necessary to practice crop rotation on marsh soils? Discuss.

25. What types of farming may be practiced on muck and peat soils? What

are some of the factors determining the choice to be made?

26. Which type of farming assures greatest profits?

27. Upon what depends, in a large measure, the future development of large

tracts of marsh lands?

28. If possible, describe a particular case of management of marsh land.

29. For an outline summary of this chapter, see table of contents.

CHAPTER XVIII

SANDS AND THEIR MANAGEMENT

SANDY soils include four important classes, namely: (1) Coarse
and medium sand; (2) fine sand; (3) sandy loam, and (4) fine
sandy loam. The last two classes are generally recognized as
excellent soils, and their management requires no special attention
when due consideration is given to the maintenance of their
fertility. When depleted they require about the same treatment
in their improvement as do loams and silt loams. The medium

FIG. 205. — Shifting or dune sand.

sands and the fine sands, on the other hand, have certain charac-
teristics which necessitate a special knowledge for their success-
ful management.

The fine sands are much more desirable soils than coarse sands.
This fact is usually indicated by the character and size of the under-
growth of cut-over lands or by the original vegetation which they
are supporting or have supported. Heavy growth and hardwoods
usually indicate the presence of more fine material in the soil and a
higher content of plant-food elements, which mean more favorable
cropping possibilities.

Dune or shifting sands (Fig. 205), being of little or no agricul-
tural value, are not considered in this chapter.

Advantages in Farming Sands. — There are several advantages
to be considered in farming sands, namely : (a) They are warm and
quick soils; (b) they are especially well adapted to the growing
of small fruit, early vegetables and such crops as strawberries,

309

310

SANDS AND THEIR MANAGEMENT

melons and pineapples; (c) they are easy to till; (d) they can be
worked readily during wet seasons or when wet; (e) they respond
quickly to proper fertilization; (/) they are profitable in pro-
portion to their valuation.

Sand Problems. — The main problems encountered in cropping
sands may be summarized as follows :

Problems in Sand Management and How to Solve Them

Problems

Solution

Low in nitrogen and organic matter

Soils usually acid

Deficient in phosphorus and potassium

Too loose seed-bed

Moisture supply uncertain

Subject to wind-action

Apply manure; grow legumes

Lime the soil

Apply mineral fertilizers

Roll the land; increase organic matter

Conserve moisture; increase organic
matter

Wind-breaks; proper field manage-
ment

Nitrogen and Organic Matter. — The need of nitrogen and
organic matter is of the greatest importance in sand farming. For
this reason, the growing of legumes such as soybeans, cowpeas,
velvet beans,1 mammoth clover, etc., should be given the greatest
attention. Many times sands are so poor that winter rye is the only
crop that can be grown. This rye should be plowed under in the
spring, and soybeans, mammoth clover or some other suitable legume
planted. The entire legume crop should be plowed under when still
green. Following this a short rotation may be put into practice,
not only to provide an income, but to improve the soil as well.

Increasing the organic matter and maintaining it constitutes
a big problem. The whole program in sand farming should center
on this problem. Agricultural lime, manure, commercial fertil-
izers, and green manure crops should be used particularly to
increase the growth of clover and other legumes, these being
necessary to assure good yields of other crops.

Manure for Sands.— Since sands are usually deficient in the
three important plant-food elements, manure is an excellent
fertilizer to use. When well decomposed, its application as a top-
dressing on plowed ground into which it is disked seems to give
best results for corn. It is advisable, however, to apply much of
the manure as a top-dressing on the clover fields.

1 Velvet beans and cowpeas are important legumes for soil improve-
ment in the South.

NITROGEN FERTILIZERS 311

Manure alone does not supply the full needs of sands. Phos-
phate and often potash fertilizers are necessary to develop properly
balanced soils.

FIG. 206. — Sand without the wherewithal to produce. (See Fig. 207.)

FIG. 207. — From poor to productive sand in three years. Lime and proper fertilizers.
Same soil as shown in Figure 206.

Nitrogen Fertilizers. — (See index.) The low supply of organic
matter in these soils necessarily means a low nitrogen supply, hence
the urgent need of nitrogen. However, the use of commercial
nitrogen fertilizers, such as nitrate of soda and ammonium sulfate,
as the main sources of nitrogen in general farming on sands is
not recommended, since these fertilizers cannot take the place of

312 SANDS AND THEIR MANAGEMENT

legumes and manure in supplying the much-needed organic
matter (see index).

Liming Sands. — For most sands lime may be regarded as the
second important need in their improvement. This is necessary,
not only to supply available calcium for crop needs, but to render
the fertilizing elements in the soil more available as well (Figs.
203 and 207).

Without sufficient lime alfalfa cannot be grown on acid sands.
Mammoth, medium red, crimson and Japan clovers are much
benefited when sands of slight to medium acidity are limed.

FIG. 208. — A good crop of soybeans on sandy soil.

Soybeans (Fig. 208), cowpeas, and velvet beans grow very well on
sands having slight to medium acidity, but when the soils are
strongly acid liming is necessary for best results (p. 229).

Phosphorus and Potassium Needs. — Some sands, especially
those of slight to medium acidity, require phosphorus as second
in importance to nitrogen and organic matter. On most sands,
however, phosphate and potash fertilizers are indispensable;
the potash being of most value during the first few years
of improvement.

Of the phosphate fertilizers, acid phosphate and steamed bone
meal are most commonly used. Best results in the use of these
fertilizers are secured after the nitrogen and organic matter have
increased, and acidity has been reduced by liming. Acid phos-
phate may be applied at the rate of 300 to 500 pounds to the acre,
applied as a top-dressing and disked in. This application should
be made to benefit the legume crop, and may be repeated at least
once in a three-year rotation.

THE MOISTURE SUPPLY 313

One hundred twenty - five pounds of muriate of potash
should also be applied with the phosphate. Additional amounts of
50 to 100 pounds of the potash fertilizer may be applied per acre
for corn and potatoes, respectively.

For more permanent soil improvement rock phosphate (see
index) may be used instead of acid phosphate, but not until the
soils have been well enriched with organic matter.

Use of Mixed Fertilizers. — Many have found it profitable,
in addition to the use of manure and special fertilizers, to use
from 125 to 200 pounds of mixed fertilizers per acre for corn,
applied in the hill or drill and about 500 pounds for potatoes.

Usually, it is advisable, in the spring, to apply a light top-
dressing of manure to the rye to increase the yield and especially
to benefit the clover seeding. When manure is not available, an
application of 400 to 500 pounds of a 2-8-1, or a 4-12-0 mixed
fertilizer (NPK) may be substituted. A mixture of 100 pounds
of dried blood and 300 pounds of acid phosphate per acre gives
good results. The fertilizer should be mixed with the soil through
disking or harrowing. Harrowing grain on sand in the spring does
not injure the crop, but greatly improves it.

The Seed Bed. — Much care should be given to the preparation
of the seed bed. Firmness is desired (see Tillage, in index). This
can be accomplished through good plowing, thorough harrowing
and by using a corrugated roller or cultipacker (p. 155). The
importance of close contact between the soil and the seed (Fig. 21)
and, later, between the soil and the young roots should always be
kept in mind in preparing a seed bed on sand, and in planting and
sowing. The presence of a good supply of organic matter is an
important factor in preparing a proper seed bed.

The Moisture Supply. — The water-holding capacity of sands
is low (see index). Moreover, this moisture is easily secured by
crops and thus this comparatively small amount of moisture, if
not replenished by rains, is soon used up. Crops on sand, therefore,
frequently suffer for want of moisture during dry periods. To
lessen this injury, moisture conservation and control should be
given special attention. Soil mulching is important. Disking
and " dragging" winter rye in the spring is good practice. Sowing
such legumes as soybeans and cowpeas in rows to permit of cultiva-
tion is advisable. In case of potatoes, endeavor to grow thrifty
vines to shade the ground. When the subsoil is sand, subsoiling
or deep spring plowing should never be done.

314

SANDS AND THEIR MANAGEMENT

The only way to increase the water-holding capacity of sand
is to increase the organic matter (Chapter IX).

" Blowing " of Sands. — Because of the lack of sufficient
material like clay and organic matter to bind the soil particles
together, sands are loose and subject to wind-action. Often during
the early growing period before the ground is covered by growing
crops, high winds blow so much sand as to greatly injure and even
destroy crops, especially corn and potatoes.

FIG. 209. — Press- wheel attachment for grain drill. Splendid to use on sandy soils. (Fig. 98.)

Wind-breaks are means of protection to a limited extent.
These may be planted, or when trees are cut in land -clearing,
rows of trees or narrow strips of timber may be left for this purpose.
A very effective way of protecting lands which are subject to
wind-action consists in laying them out in long narrow strips at
right angles, or nearly so, to the prevailing winds. These strips
should be managed so as to have crops that cover the ground in the
early spring, such as clover or rye, alternate with cultivated strips.
Sands become less subject to " bio wing" when, by proper manage-
ment, they are enriched in organic matter.

Sand fields become much more exposed to wind-action when
they are fall plowed. It is usually best, therefore, to plow exposed

CROPS FOR SANDS

315

sand fields in the spring. Fall cover-crops should be given
much attention.

Other Points on Management. — In clearing sand lands, grass,
leaves, etc., should never be burned, but plowed under when-
ever possible.

Plowing. — First plowing should never be more than four and
one-half to five inches deep, and subsequent plowing not deeper
than six inches. Spring plowed land should be made firm by har-
rowing and rolling. A weeder is a good implement for sandy
soils (Fig. 210).

FIG. 210. — Riding weeder, a splendid tool for sandy soils.

Drill Best for Sands. — It has been clearly shown that the drill
grain-sower is the best to use on sands (p. 314). It is best to drill
in the clover seed also, not with the grain, but separately and in
opposite directions to the grain drill-rows (p. 79).

Peat for Sand Improvement. — Many sand sections include
numerous peat marshes. When convenient, the peat may be
applied to the sands to increase the organic matter and the nitrogen
supply. In some countries this is a common practice. Twenty-
five loads may be applied to the acre. It is quite necessary to
supplement the peat with phosphate and potash fertilizers.

Crops for Sands. — Sands respond readily to proper treatment.
Moreover, they warm up quickly and are easily worked. When

316 SANDS AND THEIR MANAGEMENT

rightly managed, therefore, they are well adapted for growing
potatoes, strawberries, melons, pineapples, garden truck and
small fruit.

Following is a brief discussion concerning the growing of
other crops.

Soybeans. — A splendid legume for sand improvement. Grows
well on slightly to medium acid soils. Sands strongly acid should
be limed. Inoculation is usually necessary. Usually best to plant
in rows. Supply mineral fertilizers. Ranks high in feeding value.
A good cash crop (Fig. 129).

Mammoth Clover. — An excellent clover for poor sands. Liming
necessary if soils are acid. Inoculate for best results. Sow with
drill. Top-dress young seeding with manure or mixed fertilizers.

Cowpeas. — Of particular value in the Southern states, though
adapted to a wide range of climate. May be grown for seed and
feed. Inoculation important. Well adapted to slightly or medium
acid soils. Hay ranks lower in feeding value than soybeans.

Velvet Beans. — A most useful soil-enriching legume for the
South. Grows well on acid soils. Inoculate, except when grown on
land which has grown lespedeza or cowpeas successfully. On very
poor soil use acid phosphate. Has high feeding value.

Crimson Clover. — A clover for the Middle Atlantic states.
Lime strongly acid soils.

Medium Red Clover. — Grows best on non-acid soils. Sow in
same manner as mammoth clover. May take the place of mam-
moth clover when soils' become improved.

Vetch. — In some sections this plant has not attained the favor
as other legumes. First attempts are often failures. Good to sow
in rye. Inoculate. Lime strongly acid soils.

Alfalfa. — Crop too uncertain. Should not be grown unless
soils are well supplied with lime and highly improved. Inocula-
tion necessary.

Ryq (winter). — Best grain for poor sands. Sow with drill.
Top-dress with manure or fertilizers. "Drag" or harrow in the
spring. Avoid too thick seeding. Plant early to permit of good
winter covering.

Potatoes. — Well adapted to sands. Best to follow a green-
manuring crop, or be grown on clover sod. Apply mineral fertil-
izers in drill.

Corn. — Can be grown with good success on sands. Best to
grow on cover sod.

CROP ROTATION 317

Oats. — Best results when sands are improved.

Barley. — Sands are poor barley soils.

Grass and Pasture. — Sands poorly suited to grass or pasture.

Brome Grass. — Gives promise for good pasturage on sands.

Buckwheat. — Well adapted to sands.

Cotton. — Cotton grows best on richer soils.

Sugar Beets. — Sands are not adapted for the growing of
this crop.

Crop Rotation. — Short rotations are best for sands. In planning
the rotations, legumes, catch-crops and green-manuring crops
should be given special consideration; and no grain or cultivated
crop should be grown twice in succession. Moreover, rotations
must necessarily change to fit the stages of development.

In beginning sand improvement the following rotations
are successful :

A — 1. Soybeans to plow under (sown on land having had fall
rye plowed under). 2. Soybeans for seed or hay (rye sown in the
fall). 3. Rye (seeded with mammoth clover or vetch which is
plowed under). The clover may be left for hay, and the hay fol-
lowed by soybeans for seed or hay.

B — 1. Soybeans or cowpeas (to plow under or for seed, depend-
ing on the soil). 2. Corn or potatoes (fall sown rye or vetch for
cover crop).

C — 1. Soybeans for seed or hay (fall rye). 2. Rye (soybeans
sown immediately after harvest).

The following are typical rotations when a definite system of
farming has been established :

D — 1. Corn (soybeans planted with cron; fall rye). 2. Rye
(seeded with mammoth clover). 3. Clover (second growth
plowed under).

This may be made a four-year rotation by growing soybeans
after corn. Soybeans may be grown the third year instead
of clover.

E — 1. Corn (fall rye seeded in corn at last cultivation). 2.
Rye (soybeans sown immediately after harvest, and plowed under
in fall). 3. Mammoth clover, seed without nurse crop. 4. Clover
for hay. Fifth year may be pasture.

F — 1. Clover. 2. Corn (rye sown in corn at last cultivation,
and plowed under in the spring). 3. Potatoes (rye sown in fall
and clover seeded in the spring). 4. Rye.

G — 1. Vetch and rye (volunteer vetch plowed under for

318 SANDS AND THEIR MANAGEMENT

potatoes). 2. Potatoes (fall sown rye). 3. Rye (seeded to clover) .
4. Clover (second growth plowed under). 5. Corn (soybeans
in corn).

H — 1. Velvet beans (plowed under), followed by rye (plowed
under about May 1). 2. Cowpeas (cut for hay), followed by crim-
son clover (sown in fall and plowed under about May 1). 3. Corn
and velvet beans.

Types of Farming. — When the whole farm consists of poor
sand, the real problem is to find a way whereby the farmer with
limited means can begin at once to realize an income which he
can use to improve the soil and to develop a well-balanced and
profitable system of farming. It costs money to buy the needed
fertilizers and agricultural lime, and it is temporarily expensive
to grow certain crops and plow them under. The farmer must
begin a system of cropping which will, at the outset, give him
fairly certain and continuous returns.

Soybeans, cowpeas and velvet beans (depending upon the
section of the country) offer the quickest and surest sources of
income. When the sands are poor and organic matter and nitrogen
are essential to ensure any crop at all, a portion of the legume crop
should be plowed under. If a rotation such as A is planned at the
start, one-third of the crop is plowed under (legume), leaving two-
thirds of the season's crops for sale. Perhaps after the first three
years, or when the three-year rotation is completed on each field,
a rotation such as D or E may be established, or a combination of
the two. In rotation D the soybeans may be grown for sale as
seed, and later on when animals are brought on the farm, or when
the number is increased, the soybeans may be grown for forage
except when opportunity is afforded to sow the crop after harvest-
ing rye, for green-manuring (rotation E) .

During the first few years legumes should constitute the major
crop, and at the same time sufficient corn and rye should be pro-
duced to meet the feeding requirements of the horses, a few cows
and pigs, and a few head of young stock.

Sands afford splendid opportunities for a combination of potato
and grain farming, provided particular attention be given the grow-
ing of legumes, and to the use of fertilizers and agricultural lime.
This type of farming demands much less capital than livestock or
dairy farming, though the distribution of labor is not so good.

In many sand sections which are favorably located, dairying
seems the best type of farming to be considered. Fences for cows

TYPES OF FARMING

319

FIG. 211.— "Hungry soil." Sand. To" left, unfertilized. Yield of potatoes, thirteen
bushels per acre. Yield of corn, three bushels per acre. (Wisconsin Station.)

FIG. 212. — Profitable sand. Corn on clover sod, manured. (Wisconsin Station.)

are easy to build and dairy cows will turn into profit large quanti-
ties of roughage that can be produced so readily on sands. Further-
more, the manure produced can be used to good advantage in soil
improvement (contrast Figures 211 and 212). An extra silo for

320 SANDS AND THEIR MANAGEMENT

summer feeding will solve, in a large measure, the problem of sum-
mer pasture, which is rather difficult to maintain on sands.

Little need be said concerning sand fields which form parts of
many farms. Through intelligent management many of these
fields are sources of highly profitable returns. These fields,
together with the successful sand farms being operated, indicate
the possibilities that may be realized in the proper development
of sand lands that are at present considered of little agricul-
tural value.

Field Studies. — 1. Study systems of sand management, particularly on
successful farms.

2. Study the character of subsoil in sandy fields. Which are more desir-
able than others? Why?

Home Projects. — Select three acres of sand or sandy soil, or an acre,
and divide into three equal portions. Fertilize properly. Establish a three-
year rotation of rye, mammoth clover and corn. Individual students or the
school may continue the rotation for at least six years, and observe results.

2. Conduct projects in the proper management of sandy soils as directed
in the study of this chapter.

QUESTIONS

1. Name the four important classes of soils grouped under "sands." How

do they differ in texture?

2. What are the indications of a desirable sand farm?

3. Name the special problems in sand management and state briefly the

solution of each.

4. What is of the greatest importance in sand improvement? Discuss.

5. Is manure the best fertilizer to use on sand? Discuss its use.

6. Should a sand farmer buy nitrogen fertilizers? Why?

7. Discuss the importance of agricultural lime in sand improvement. What

kinds of material may be used? Discuss their application.

8. What mineral fertilizers are best for sands? Discuss their use and

application.

9. What are mixed fertilizers? How may they be of value in sand farming?

10. Discuss the preparation of the seed bed on sand.

11. What is the problem concerning the moisture supply in farming sand

lands? What means may be employed for solution of this problem?

12. Discuss the "blowing" of sand and its prevention.

13. How should sands be plowed? Explain.

14. Which are better for sowing grain and clover on sands, broadcast sowers

or drills? Discuss fully.

15. Tell of the value of peat in sand improvement.

16. Name some crops especially well adapted to sands. What may be said

of alfalfa, oats, barley, grass and pasture, sugar beets and cotton?

17. Discuss crop rotation in relation to sand management.

18. What is the main handicap of the farmer of limited means who begins

farming on sand, especially when the soil is poor?

19. What types of farming are adapted to sands? Discuss each.

20. Have you seen a case of successful farming of sandy land? Give the ele-

ments of success.

21. For an outline summary of this chapter, see table of contents.

CHAPTER XIX

MANAGEMENT OF CLAYS AND DEPLETED SILT LOAMS

CLAY MANAGEMENT

CLAY soils are quite the opposite of sands in many respects.
Sands are loose and open, while clays are sticky and "tight."
Sands are the easiest soils to work, and clays the hardest. The
special characteristics of clay soils are due largely to their fine
texture. They are composed of thirty per cent and more clay,
and the remaining material consists of silt and fine sand.1 They owe
their origin, commonly, to the settling out of fine sediments which
have been carried into bodies of water by streams.

Included in this class are the "gumbo" soils which are so preva-
lent in certain sections and localities. Gumbo is usually black
clay soil occurring either on river bottoms or flat upland. This
soil is more sticky and bakes more easily than any other kind of soil.

Points in Favor of Clays. — Heavy clay loams and clays have
a few points in their favor, namely: (a) They are excellent for
general farming, for hay and grazing; (b) they are well adapted
to clovers and small grains; (c) they can usually supply crops
with moisture better than sands during a dry period.

Special Problems. — Clay soils are highly productive when they
are given the proper treatment. The special management problems
which they present and their solutions are briefly stated in the table.
Problems in Clay Management and Their Solutions

Problems

Usually cold and wet
Difficult to develop good tilth

Organic matter and nitrogen usu-
ally low

Phosphorus often deficient
Subject to washing (erosion)

Solutions

Proper surface and subsurface

drainage
Thorough drainage; plow when fit;

grow grass and pasture
Grow legumes and grass; pasture

Use proper phosphate fertilizers
Keep grassed; terrace; deep plow-
ing, etc.

1 The average mechanical composition of nearly 2000 clays is as follows:
Forty-two per cent clay, thirty-six per cent silt, sixteen per cent of very fine
sand and fine sand, five per cent medium and coarse sand, and one per cent
fine gravel.

21 321

322 MANAGEMENT OF CLAYS AND DEPLETED SILT LOAMS

Importance of Drainage. — Drainage is usually the first step
in the improvement of clays, since they are so retentive of moisture
and do not permit water to percolate easily through them. Thus
it is that clay soils are usually wet and cold and lack proper aera-
tion. Attention should be given both surface drainage and tiling
(Chapter IX) . Through proper surface and under-drainage these
soils warm up better, become better aerated, and are much
improved in their productiveness.

Fid. 213. — When heavy soils are plowed too wet they become puddled.' Hard lumps result.

Tilth. — The greatest problem in the cultivation of clays con-
cerns tilth (see index). When plowed or worked too wet the soil
particles are forced together, and the result is a hard, lumpy soil
when it becomes dry (Fig. 213). When exposed to a hot, drying
sun a moist or wet clay easily bakes. The preparation of a good
seed bed, therefore, is difficult and requires much extra labor
(see "Clod Crushers")-

Thorough drainage is an important factor in the development
of good tilth. A second consideration is careful plowing. Clays
should never be plowed or worked when they are wet. Often the
bad effects of plowing heavy soils when too wet extends through
several years. When such lands have become hard and lumpy
because of careless plowing, freezing and thawing is about the only
process that will restore a crummy or granular structure. This is
best accomplished through fall plowing.

ORGANIC MATTER AND NITROGEN

323

Organic matter has a wonderful effect in loosening heavy soils.
Improvement in this direction can best be accomplished by growing
grass and by pas-
turing. Combin-
ing red-top, timo-
thy and clover
makes an excellent
grass mixture for
any heavy soil.
The roots of
grasses loosen the
soil and in a large
measure prevent
puddling.

The growing
of sweet clover on
clays for soil im-
provement is
highly recom-
mended. The
deep roots pene-
trating the "tight"
subsoil improve
drainage, favor
aeration and add
much organic
matter (Fig. 214).

The use of air-
slaked lime or
quicklime on clays
tends to develop
better tilth, espe-
cially when acid.
This effect, how^
ever, is percepti-
ble only when
lime is used con-
tinuously for
several years. Usually clays are not acid or only slightly so.

Organic Matter and Nitrogen. — Clay soils are commonly
deficient in organic matter and nitrogen, especially those which

Fio. 214.— The upper portion of a sweet clover root,
roots will puncture tight and hard subsoils.

Such

324 MANAGEMENT OF CLAYS AND DEPLETED SILT LOAMS

were originally covered with forest growth. The growing of grasses
and pasturing have been mentioned as means of increasing the
organic matter. The plowing under of clover and green manuring
crops, and the use of manure are especially recommended as means
of increasing the nitrogen supply.

Phosphates for Clays. — Heavy soils usually contain large
amounts of potassium. When well drained and sufficiently supplied
with organic matter potash fertilizers are seldom required on
these soils.

The phosphorus needs of clays are quite general, so that the
use of phosphate fertilizers is usually highly profitable. For imme-
diate results, acid phosphate may be used at the rate of 200 to 300
pounds per acre for grain and 400 to 500 pounds per acre for corn.
Rock phosphate, when mixed with manure or plowed under with
clover or green rye, has given excellent results (Fig. 148, p. 198.
See Rock Phosphate, index). Basic slag is especially good to
use on clays, but in most sections of the United States it is
not obtainable.

Many clays are red in color, due largely to the presence of
iron compounds. Frequently this iron makes the phosphorus
unavailable. On some of these soils acid phosphate is rendered
entirely ineffective within a year or two after it is applied. The
application of agricultural lime is an effective remedy.

Erosion. — Because of their location or topography, many
clay soils are particularly subject to washing, or erosion. The
cultivation of these lands greatly increases their tendency to wash.
In most cases it is best to keep such lands in grass. When some
of the more gentle slopes are brought under cultivation, plowing
should be done at right angles to the slopes. Often it is advisable
to terrace a slope or leave open dead furrows in such a way as to
enable the surf ace water to run off by following more gentle inclines.

Deep fall plowing and subsoiling also aid in preventing erosion
(see index). A further discussion of erosion may be found in
Chapter XXIII.

Other Points on Clay Management. — Clearing clay lands of
underbrush, small stumps and dead timber is not, as a rule, a
very expensive process. Removing stumps by combining the use
of dynamite and the stump puller seems to be the most economical
method. It is much easier to blast out stumps when the ground is
moist or wet and when they are given a few years to rot after the
timber is cut.

ROTATIONS AND TYPES OF FARMING 325

When cleared of timber and brush it is advisable to get clover
started as soon as possible, not merely to provide pasturage and hay,
but to help in controlling the weeds and to improve the soil. A
spring-tooth harrow or a disk is helpful in getting the clover seeded.

Plowing. — It requires a good plow to turn heavy clays well.
In some sections the disk plow is the best to use. Fall plowing is
usually advisable. Subsoiling to deepen the seed bed and to create
a more open subsoil is sometimes practiced. Dynamite is also
used at times to open the subsoil so as to facilitate the entrance of
air, water and roots. It is best to do either subsoiling or dyna-
miting when the ground is sufficiently dry to prevent puddling
(Chapter X).

Crops for Heavy Clays. — Because of their fine texture, clays
are especially well adapted to crops having fine and fibrous roots,
such as red-top, timothy, etc.

Crop adaptation to heavy clays may be summarized as follows:

Crops Well Adapted Crops Which Can Be Crops Not Adapted

to Clays Grown Successfully to Clays

Red-top Sweet clover Barley Vegetables

Timothy Wheat Corn Truck crops

Clover Oats Potatoes Sugar beets

Field peas Rye Rutabagas

Turnips

Rotations and Types of Fanning. — Much depends upon a
good system of cropping to increase the productive power of
clays. The following are good rotations for dairy farms:

A — 1. Cora (manured). 2. Grain (seeded to clover and timo-
thy). 3. Clover. 4. Pasture or mixed hay.

B — 1. Wheat (seeded to sweet clover to plow under). 2. Corn
(manured). 3. Oats (seeded to clover). 4. Clover.

When the oats are seeded to a mixture of grasses this may be
made a five-year rotation with pasture the fifth year.

C— 1. Wheat (seeded to clover); (fertilized). 2. Clover. 3.
Corn (properly fertilized). 4. Peas (peas for sale as seed).

D — 1. Small grain (seeded to mixed grasses). 2. Clover. 3.
Mixed hay or pasture. 4. Peas (cash crop). 5. A cultivated crop.

For grain-farming, the following rotation is well adapted:

E — 1. Spring wheat (seeded to clover and timothy). 2. Clover
(cut for seed). 3. Mixed hay. 4. Peas (for sale as seed).

IMPROVEMENT OF DEPLETED SILT LOAMS

Depleted silt loams are common particularly in the Eastern
and Central states. They are the result of too severe cropping,

326 MANAGEMENT OF CLAYS AND DEPLETED SILT LOAMS

with little or no attention given to the maintenance of their fer-
tility. As a rule, these soils are low in organic matter and nitrogen,
they are commonly acid, and are in need of available phosphorus.
Liming is usually the first step to be considered in their improve-
ment, the object being, mainly, to improve the conditions for grow-
ing clover and other legumes. Plowing under legumes is recognized
as the best method to increase the organic matter and nitrogen.
Manure, when available, generally gives good returns when
applied to the clover fields. Liberal applications of soluble phos-
phates should be made to the grain and cultivated crops. Acid
phosphate is generally considered the best phosphate fertilizer to
use in beginning soil improvement. Later on, when improvements
shall have been well advanced, rock phosphate may take the place
of the acid phosphate. A short rotation including clover is also
an important factor to be considered in the regeneration of these
soils (Chapters XII, XIII, XV).

Field Studies. — 1. Select a run-down farm and make careful observations
as regards general appearance, weeds, character of crop growth, and soil
conditions. Suggest remedies.

Home Projects. — Select three acres of depleted silt loam, or an acre, and
divide into three equal portions. Fertilize properly. Establish a three-year
rotation, corn, grain and clover. Plow under the first crop of clover, and always
the second growth. Students may continue the rotation for at least six years,
and note soil improvement.

Other rotations suited may be substituted, or may be conducted in addi-
tion to the one suggested.

QUESTIONS

1. Compare clay soils with sands in their workability and texture. What

is " gumbo'"?

2. Name the special problems in the management of clays. State briefly

their solutions.

3. Discuss drainage in relation to clay management: (a) benefits; (6)

methods; (c) depth of tile, fall, "blinding," distance apart to lay lines
of tile.

4. Discuss tilth in relation to clay management.

5. How may the organic matter and nitrogen in clay soils be increased?

6. What special fertilizer do clays commonly require? What is the relation

of lime to fertilizer needs on some clays?

7. What is erosion and how does it affect clay lands? Name some means

of prevention.

8. Describe a good method for clearing stumpy clay lands.

9. Name crops that are particularly adapted to clay soils. Crops that can

be grown successfully on good management. What crops are not
adapted to clays? Why?

10. Name two good rotations for dairy-farming on clay land. A rotation for

grain-farming.

11. Discuss the improvement of depleted silt loams.

12. What crops have you observed growing on very heavy clay soils?

13. See outline summary of this chapter in table of contents.

CHAPTER XX

FARM MANAGEMENT AND CROP ROTATION

Soil Problems Are Prominent in Farm Management. — The

most successful system of farming is that which gives the largest
profit, increases soil fertility, and brings to the farmer and his
family the largest amount of happiness. Successful farm manage-
ment presents many problems, the most important of which con-
cerns the growing of suitable crops, the adaptation of crops to soil,
the care of the soil and crops, the disposition made of the crops, and
the distribution and use of labor. The problems involving soil
relations are usually of fundamental importance and thus are
given special attention. Indeed, it is self-evident that productive
soil is the basis of profitable farming.

The old style of farming has been largely the one-crop system —
a system which has generally led to soil depletion. Modern agri-
culture and scientific farming demands the growing of several
crops, chiefly because of its beneficial effects on soil fertility. Thus
diversified farming has become of national importance.

Advantages in Growing Different Crops. — There are several
advantages to be gained in growing different kinds of crops,
important of which are: (a) It economizes in the use of labor;
(6) a more dependable income is assured; (c) it permits of
crop rotation.

Different kinds of crops necessarily require different planting
and harvest times. The labor required to care for the crops is ex-
tended more uniformly over a longer period than when just one crop
is grown. Moreover, a diversity of crops encourages the keeping
of more livestock, the care of which utilizes labor, especially
during winter months.

The growing of one crop means just one source of farm income,
and that is rather uncertain at times. The growing of several
crops provides a more dependable income. When the weather is
bad or prices low for one crop, the conditions or prices are usually
favorable for some other crop. To establish more than one source
of income is good business.

It is self-evident that rotation is made possible only when

327

328 FARM MANAGEMENT AND CROP ROTATION

two or more different crops are grown. The importance of rotation
in farm management and its application are fully discussed in
the following paragraphs.

Rotation an Essential Factor in Farm Management. — Crop
rotation is a most essential factor in successful farm management,
because it aids materially in increasing and maintaining soil
fertility, in systematizing farm operations, and in solving certain
other soil and crop problems. The relation of rotation to soil
fertility has been fully discussed in Chapter XV.

Rotation implies system. The adoption of definite cropping
plans is the beginning of systematic farming, affecting not only the
growing of crops, but field management and the use of labor as well.

Problems concerning the adaptation of crops to certain fields,
the effect of one crop on another, soil renovation, the management
of special soils, etc., are best solved through crop rotation.

Rotation in Practice. — In establishing a fixed rotation, it is
necessary to divide the farm into uniform fields or units on which
are grown the different crops. Each year the crop on each field or
unit is changed according to the adopted plan. For example:
A certain farm consists of 100 acres, sixty acres of which are under
cultivation and are divided into three twenty-acre fields; the
remaining forty acres includes permanent pasture, orchard, yard,
garden, etc. The farmer wishes to grow annually twenty acres,
each, of corn, oats and clover; thus a three-year rotation is planned
as follows:

Field I

Field II

Field III

Year 1 . .

Corn

Oats

Clover

Year 2

Oats

Clover

Corn

Year 3

Clover

Corn

Oats

This is the simplest conception of a practical rotation. Com-
paratively few farms, however, lend themselves to such a simple
arrangement because of certain conditions or factors which
present themselves. Usually two or more different rotations are
necessary on each farm .

Factors Which Determine Kinds of Rotations. — The rotations
best suited to any particular farm are determined by —

(a) The feeding requirements of the stock kept.
(6) The kind and amount of cash crops grown.

PROCEDURE IN PLANNING ROTATIONS 329

(c) The income to be derived.

(d) The profitable distribution of labor.

(e) The topography of the farm.
(/) Soil conditions.

In stock farming, the feeding requirements determine hi a large
measure the kind and amount of crops to be grown; and this
must necessarily vary with different types of stock farming.
Besides growing the crops required for feed, most farmers grow
additional cash crops, such as wheat, barley, tobacco, sugar beets,
cabbage, etc. This usually complicates the general cropping plans.
Usually the growing of alfalfa also causes irregularities hi the rota-
tions.1 Rotations on grain farms may be different than those on
stock farms; and the systems of cropping in truck farming are
quite unlike all others. Moreover, rotations in one section of
the country differ from those of another, because of dissimilar
crop adaptation.

The income to be derived and the distribution of labor are of
special importance in determining rotations, especially in grain-
farming and in the growing of truck crops, since the object upper-
most in the mind of most farmers is not soil improvement, but the
making of money. These two endeavors, however, can be happily
combined. It is much easier to plan rotations and arrange fields
on land that is level or slightly rolling than on a hilly farm. Many
farms have hillsides which must necessarily be cropped in a
different manner than the more level portions in order to control
soil erosion.

Soil conditions most frequently affect the rotations. For
example, many soils are strongly acid, which condition is unfavor-
able for certain crops (Chapter XIII) . Peat and muck soils, sands
and heavy clays require special attention with respect to cropping.
A field of depleted silt loam should not be included in rotation
plans designed for highly productive fields.

Procedure in Planning Rotations. — Rotations on many farms
can be planned and carried out with little or no difficulty. On
old farms, it is not always easy to establish fixed or definite rota-
tions. Usually it becomes necessary to reorganize the whole farm.

1 When a farmer succeeds in getting a good field of alfalfa he usually
leaves it in alfalfa so long as it produces profitable crops. A rotation including
alfalfa is always longer and usually more irregular than a rotation in which
clover is grown as the principal legume.

330 FARM MANAGEMENT AND CROP ROTATION

In doing this it is important to keep in mind the entire business
of any particular farm so that whatever rotations are adopted
they will not disturb in any great degree the type of farming
already established, unless the farming business itself is radically
changed. Moreover, in reorganizing any farm, two or three years
may be required before the revised cropping plans can be fully
adopted, because existing conditions must be considered, as regards
pasture, hay fields, size and arrangement of fields, drainage, etc.

Bearing in mind all the determining factors, the procedure
in planning rotations for any particular farm may best be started
in the form of problems, or cases, as follows :

Case A. — A stock farm already stocked.

1. First determine the amount of grain, corn and hay, etc.,
necessary to meet the feeding requirements.

2. Determine the average yields on the farm.

3. Determine the acreage necessary to produce the required
crops for feed.

4. Make a map of the farm just as it is with fields showing
acres in each.

5. Number the fields in some convenient way.

6. Consider the rotations best suited to soil conditions or types
of soil in each field or on various portions of the farm

7. Plan to grow each year the required amounts of the dif-
ferent crops.

8. Rearrange the fields if necessary to simplify the cropping
plans and to aid in general field management.

Case B. — A farm designed for stock but not yet stocked.

1. Determine the kinds of stock to be kept.

2. Determine the acreage available for growing crops (includ-
ing pasture).

3. Ascertain the average yields of the crops to be grown.

4. Estimate the amount of stock that can be conveniently kept.

5. Determine definitely the acreage necessary to grow the
crops required for feed.

6. Proceed as in Case A, point 4.

Case C. — A grain farm, with soil problems.

1. Make a map of the farm; show fields, acreage, and indicate
soil problems and conditions.

2. Determine crops to be grown.

3. Plan rotations best for special soils, to improve poor soils
in certain fields, and to best meet other soil conditions.

CROP ROTATION CHART

331

4. Rearrange the fields or combine small fields into larger units,
whenever possible, to facilitate farm management. (When no
special soil problems or conditions are to be met, the fields may be
rearranged at once and the proper rotations adopted.)

Case D. — Rotations in truck farming, with soil problems. —
Proceed as in Case C.

Crop Rotation Chart. — In planning rotations on farms having
soil and crop problems which must necessarily complicate the
cropping plans, a rotation chart is of great help. For example, the
cropped portion of a farm, excluding permanent pasture, consists
of sixty acres, which are divided into six ten-acre units. Twenty
acres each of corn, oats and hay (ten of alfalfa) are to be
grown annually.

Fields I and IV are especially well adapted to alfalfa.

Fields II, III and VI require improvement, hence a three-year
rotation is planned for each of these three fields (p. 273).

Fields IV and V, and also I, are highly productive and hence
can well take care of irregularities in the cropping plans, as is shown
in the following outline:

A Rotation Chart

Year

Field I

Field II

Field III

Field IV

Field V

Field VI

1.. ..

Alfalfa

Oats

Corn

Oats

Corn

Clover

(seeded)

(on sod)

(seeded

(Top-

(fertilized)

(manured)

with mam-

dressed

moth

with

clover)

manure)

2....

Alfalfa

Clover

Oats

Corn

Oats

Corn

(seeded)

(manured)

(seeded to

(manure)

(acid

mammoth

(acid

phosphate)

clover)

phosphate)

3....

Alfalfa

Corn

Clover

Oats

Corn

Oats

(fertilized)

(light

(seeded

(manured)

(seeded)

dressing

to

(acid

manure)

alfalfa)

phosphate)

4.. ..

Corn

Oats

Corn

Alfalfa

Oats

Clover

(seeded)

(manured)

(seeded to

(Top-

(acid

(acid

mammoth

dressing of

phosphate)

phosphate)

clover;

manure)

rock

phosphate)

5....

Oats

Clover

Oats

Alfalfa

Corn

Corn

(Top-

(seeded)

(manured)

(acid

dressed

(acid

phosphate)

with

phosphate)

manure)

332

FARM MANAGEMENT AND CROP ROTATION

Application and Illustrations. — A few typical illustrations are
here given in the form of problems to show how rotations may be
established and how certain soil and crop problems can best be
solved through rotation.

\

to acres
Oats (seeded)

so acres

T/mofhy

Corn

/o acres

Qafsjseed&y

(2J

/o acres

and

C/ci/er

a

8 acres
Corn

Garder?

4O acres

\

Fio. 215. — Conditions when rotation was first considered.

Problem I. — Plan a fixed rotation for a dairy farm which is
already stocked.

Size of farm — 120 acres, all silt loam.

Corn, oats and clover are to be grown.

About 100 to 125 tons of silage, about 500 bushels of corn, at
least thirty tons of clover, and about 800 to 1,000 bushels of oats
are necessary to meet the feeding requirements.

APPLICATION AND ILLUSTRATIONS

333

Corn yields at the rate of ten to eleven tons of silage per acre,
or fifty to sixty bushels of corn; oats average about forty bushels,
and clover about one and three-quarters ton per acre.

to meet the feeding requirements, at least twenty acres of

a

Orchard
Garden

Fio. 216. — Cropping plans the second year after planning.

each crop must be grown. Fifty-eight acres are now under cultiva-
tion. Figure 215 shows the arrangement of the farm when rota-
tion was first considered.

The important soil problems are (a) a lack of available phos-
phorus, and (6) a comparatively low supply of nitrogen and
organic matter.

In order to work towards a fixed rotation without disturbing

334

FARM MANAGEMENT AND CROP ROTATION

the farming business, the second year the fields were cropped as is
shown in Figure 216. Note that the timothy sods were plowed up
and field number one was made two acres larger.

The third year the fields were rearranged as is shown in Figure
217 — a fixed three-year rotation being established.

The rotation planned and soil improvements to be made are
indicated in the following rotation chart :

Rotation Chart for Problem I

Year

Field I

(20 acres)

Field II
(20 acres)

Field III

(20 acres)

1 .

Hay

Corn (manured | 400

Oats (seeded) (200*

2

Corn (manured; 400

Ibs acid phosphate
*3er acre)
Oft* needed) (200

Ibs. acid phosphate)
Clover

3

Ibs. acid phosphate
per acre)
Oats (seeded) (200

Ibf . acid phosphate)
Clover

Corn (manure -f- 400

4

Ibs. acid phosphate)
Clover

Corn (manure -|- rock

Ibs. acid phosphate
per acre)
Oats (seeded) (200

5

Corn (manure +
1000 Ibs. rock phos-
phate per acre)

phosphate)
Oats (seeded)

Ibs. acid phosphate
per acre)
Clover

Problem II. — Plan definite cropping plans for an eighty-acre
farm which is intended for dairying.

Just seventy-four acres are available for raising the main crops
— hay, grain and corn.

Yields of crops would support, at the start, at least fifteen cows,
a few young stock, four horses and some pigs.

Summer feeding to be silage, soiling crops, grain and whatever
pasturage may become available. The farmer expects to buy
whatever additional feeds are required.

Twelve acres of alfalfa, twelve to thirteen acres of clover,
twenty-four to twenty-five acres of corn, and twenty-four to
twenty-five acres of grain are to be grown annually.

Figure 218 shows the existing conditions as regards the fields,
permanent fences, hay fields, etc.

The farm consists entirely of silt loam. Fields numbers two
and three are especially well adapted to alfalfa. Field four (a) is
the poorest field.

APPLICATION AND ILLUSTRATIONS

20 acres
Corn

acres
fia

7

20 acres
Oate seeded

Hoy

Pasfure
6 acres

B/dgs.
Orchards
Gardes?

FIG. 217. — A fixed three-year rotation established.

av acres
('*/ (/*>)

V.

c^
^
s

/2. acres

(2)

Oafs (seeded}

/3 acres

(40)
Qoverasrd 7/mot/w

5
x Cor/i Corn

/a acres
(^)

/$ acres
/4-6)

House Bar/7 j So///r?y
! Crops

J?/faJfa

Oafs (seeded}

FIG. 218. — Crop rotation on an eighty-acre farm. (Problem II.)

336

FARM MANAGEMENT AND CROP ROTATION

Because of the twelve acres of alfalfa the farm must necessarily
be divided into six units of twelve and thirteen acres each.

The following rotation chart shows the final cropping plans
and fertilizer treatments for this farm.

Rotation Chart for Problem II

Year

Field I (a)
(12 acres)

Field I (6)
(12 acres)

Field II
(12 acres)

Field III

(12 acres)

Field IV (a)
(13 acres)

Field IV (b)
(13 acres)

1.. ..

Corn

Corn

Oats

Alfalfa

Clover

Oats

(manured)

(seeded to

and

(seeded)

mammoth

timothy

clover to

plow

under)

2. ...

Oats

Oats

Corn

Alfalfa

Corn

Clover

(seeded)

(seeded to

(manure +

(manure +

mammoth

phosphate)

acid phos-

clover)

phate or

bone meal)

3....

Clover

Corn

Barley

Alfalfa

Oats

Corn

(manured)

(seeded to

(seeded)

(manure +

alfalfa)

(soluble

phosphate)

phosphate)

4....

Corn

Oats

Alfalfa

Corn

Clover

Oats

(manured)

(manured)

(seeded)

5....

Oats

Corn

Alfalfa

Oats

Corn

Clover

(seeded)

(manured)

(seeded to

(manured)

clover)

(acid phos-

phate)

Problem III. — Plan a system of cropping on an eighty-acre
grain farm in Arkansas, on which are to be grown cotton, corn,
cowpeas and oats as the main crops. Sufficient pasture is to be
provided for the horses and mules and for a few head of cattle.
As many hogs are to be kept as conditions well permit.

Soil problems to be met are, drainage and deficiency of organic
matter and phosphorus.

Figure 219 illustrates the conditions before reorganization.

Figure 220 shows how the farm was remapped. The drainage
problem was easily solved by tiling.

The following four-year rotation was adopted :

1 — Cotton followed by a winter cover crop, such as winter grain, crimson
clover and bur clover, plowed under.

2 — Cowpeas, planted in May and harvested in August.

3 — Oats or wheat. (Followed by cowpeas, plowed under).

4 — Corn (The corn may be interplanted with cowpeas, soybeans or
velvet beans, which will furnish hog feed and also serve as a green manuring
crop for next year's cotton.

APPLICATION AND ILLUSTRATIONS

337

The cowpeas, velvet beans or soybeans planted in the corn
may be used to fatten hogs.

HIGH WA Y

FIG. 219. — A farm unorganized. (See Fig. 220.)

The land surrounding the building-lot and garden may be used
for the growing of some sweet potatoes, and for hog pasture. The

/£ acres

/e acres

/£ acres

20 acres

Cowfieas

Cotton

Oafs

Wood
and

Pasture

2.

12 acres
Corn

tiog
Pasft/re

Pasture

%*%«***

FIG. 220. — The same farm organized.

three acres for hog pasture may be divided into three one-acre
fields and cropped to different crops for successive pasturing. Oats
and rye may constitute early pasture, clover for later pasture and
soybeans or velvet beans later on.
22

338

FARM MANAGEMENT AND CROP ROTATIONS

The plan of rotation and fertilization for this farm is sum-
marized in the following rotation chart:

Rotation Chart for Problem III

Year

Field I

(12 acres)

Field II
(12 acres)

Field III
(12 acres)

Field IV
(12 acres)

1

Cowpeas

Corn (500 Ibs

Cotton (800

Oats (followed

2

Oats (cowpeas

acid phosphate
per acre)

Cotton (500

Ibs. acid phos-
phate + 600
Ibs. cotton-seed
meal per acre)
Cowpeas

by cowpeas)
Corn (manure

3...

to plow under)
Corn (500 Ibs

Ibs. acid phos-
phate + 600
Ibs. cotton-seed
meal)
Cowpeas

Oats (followed

+ 500 Ibs. acid
phosphate per
acre)

Cotton (500

4

acid phosphate
+ available
manure)

Cotton (500

Oats (followed

by cowpeas to
be plowed un-
der)

Corn (500 Ibs

Ibs. acid phos-
phate + 600
Ibs. cotton-seed
meal per acre)

5

Ibs. acid phos-
phate + 600
Ibs. cotton-seed
meal)
Cowpeas

by cowpeas)

Corn (500 Ibs.
acid phosphate
per acre)

acid phosphate
per acre)

Cotton (phos-
phate fertilizer)

Oats (followed
by cowpeas)

Problem IV. — Sometimes it becomes necessary to produce much
more hay than either corn or grain. This does not necessarily
mean that a definite rotation is not possible. For example, on a
certain farm 125 acres are under cultivation, and 115 acres are
permanent pasture. The farmer wishes to raise each year in rota-
tion twenty-five acres of oats, thirty-five acres of corn and sixty
acres of hay.

One hundred twenty acres may be laid out into three forty-acre
fields, and each field cropped as is shown in Figure 221.

Problem V. — Plan a system of cropping on a 160-acre farm
in Wisconsin, which consists of twenty acres of drained peat,
twenty acres of fine sand, twenty acres of permanent pasture, and
the remaining portion of the farm consists of silt loam. All soils
are sufficiently supplied with lime.

The following crops are to be grown : Forty acres of corn, about
thirty acres of hay (about ten of alfalfa), thirty to thirty-five acres

OTHER POINTS ON ROTATION

339

of grain, twenty acres of pasture in rotation, four acres of sugar
beets', and four acres of cabbage.

Figure 222 shows the organization of the farm into eight fields
of nineteen and twenty acres each, except field VII, which contains
sixteen acres.

The plan of cropping is shown in the accompanying rota-
tion chart:

Rotation Chart for Problem V

Year

Field

(20 A)
sand

Field
II

(20 A)

Field
III

(19 A)

Field
IV

(20 A)

Field
V
(20 A)
peat

Field
VI

(19 A)

Field VII

(16 acres)

4 acres

4 acres

4 acres

4 acres

1

Rye

Corn

Clover

Pasture

Corn

Alfalfa

Clover

Cab-

Sugar

Oats

(mam-

(9KA)

bage

beets

(seeded)

moth

Oats

clover)

2

Clover

Oats

Pasture

Corn

Corn

Alfalfa

Cab-

Sugar

Oats

Clover

(10 A;

(rape)

Corn

bage

beets

(seeded)

Wheat

(9MA)

(10 A)

3

Corn

Clover

Pasture

Oats

Corn

Alfalfa

Sugar

Oats

Clover

Cab-

(rape)

Barley

beets

(seeded)

bage

(Alfalfa)

4

Rye (fol-
lowed

Pasture

Corn

Clover
Oats

Corn
(10 A)

Corn

Oats
(seeded)

Clover

Cab-
bage

Sugar
beets

by soy-

(10 A)

Oats

Alfalfa

beans)

for hay

(seeded)

5

Corn

Pasture

Oats

Corn

Oats

Oats

Clover

Cab-

Sugar

Barley

for hay
(seeded)

(9M A)
Alfalfa

bage

beets

(seeded)

Hay

(10 A)

6

Rye

Corn

Clover

Barley

Pasture

Clover

Cab-

Sugar

Barley

Clover

(9KA)

(10 A)

(9K A)

bage

beets

Corn

(Alfalfa)

Alfalfa

(9X A)

Corn

Note the cropping plan on the sand field, on the peat soil and
on field VII. Fields VI and IV are the two best fields on which
to grow alfalfa.

Manure is judiciously used. Some commercial fertilizers are
used on the sand field. Potash and acid phosphate are applied
to the peat soil. Both acid phosphate and rock phosphate are
used to reinforce the manure used on the silt loam.

Rape is sown in the corn on the peat for pasturage and for
soil improvement.

Other Points on Rotation. — In cropping hillsides, care should
be given to lessen erosion. Such fields should be kept in grass as
much as possible.

In growing alfalfa, it is often convenient to divide a portion of
the farm into strips or units and on each strip practice a five-year

340 FARM MANAGEMENT AND CROP ROTATIONS

Veld I Field H Field HI

Year I

Year 2

Year 3

Corn
(35 acres)

Oats (seeded)
(25 acres)

Clo ver
and
timothy

Peas and oafs
(10 acres)

^ Peas and oats

Clover and timothy

Timothy and clover

Peas and oats

Oats (seeded)

(25 acres)

Clo ver
and
timothy

Corn

Peas and oats

(35 acres)

Cloyer and timothy

Timothy ondclover

Peas ' and ' oats

Clover and timothy

Clover

Peas and oats
(10 acres}

timothy
Timothy and clover

Corn
(35 acres)

Oats(seeded)
(25 acres)

Fio. 221. — Sixty acres of hay, thirty-five of corn and twenty-five acres of oats in rotation.

rotation : for example, a thirty-acre field may be divided into five
six-acre strips and cropped as follows:

Rotation Chart far Alfalfa

Strip

Year 1

Year 2

Year 3

Year 4

YearS

Year 6

I
II
III

IV

V

Alfalfa
Alfalfa
Alfalfa
Grain
(seeded to
alfalfa)
Corn

Corn
Alfalfa
Alfalfa
Alfalfa

Grain

Grain
Corn
Alfalfa
Alfalfa

Alfalfa

Alfalfa
Grain
Corn
Alfalfa

Alfalfa

Alfalfa
Alfalfa
Grain
Corn

Alfalfa

Alfalfa
Alfalfa
Alfalfa
Grain

Corn

When clover fails, a suitable legume should be sown in place
of it, such as soybeans. Often oats or oats and peas are sown for
hay when the clover kills out. If in problem V, for example, the

SUMMARY

341

clover on field III should kill out, the first year, the field could
be seeded to oats or oats and peas for hay. The oats should be
seeded to clover and timothy to provide pasture the following year.
Suppose further, the clover on field I should winter-kill the second

(5)

20 acres
(Peat) \

\

Corn \
^

(*)

20 acres
Pasture

(?)

/9 acres
Clover

<

20 acres
Permane.nt
pasture

(6)
Alfalfa 19 acres

Oafs

(2)

20 acres
Corn

4 acres (T) Clover

a)

20 acres (sand)
Rye

4- acres Cabbage

4 acres Sugar beefs B Ida's

. r . etc.
4- acres (jram

FIG. 222. — Rotations meeting several problems.

year — soybeans could be sown for hay, and corn planted on the
field the third year as it is planned.

Summary. — Crop rotation is possible on any farm. It should
be the first duty of a farmer to adopt definite cropping and fertil-
izing plans for his land. It matters not where the farm, there are
adaptable legumes that can be grown in the rotation not only for
forage and seed, but for soil improvement as well. Systematic
farming has its beginning in systematic crop rotation.

342 FARM MANAGEMENT AND CROP ROTATIONS

Field Study. — Study some particular farm having soil and crop problems,
and suggest proper rotations.

Home Projects. — Each of the rotations given in this chapter may be
used as the basis for starting good home projects. Vary them to suit
local conditions.

Planning Farms. — Farms of the region should be drawn to show the plans
of the fields and the rotations. After the foregoing studies have been made
many suggestions for the improvement of the rotations may be made.

QUESTIONS

1. Name some of the problems which present themselves in farm

management?

2. Discuss the importance of the problems involving soil relations.

3. What is meant by diversified farming?

4. Discuss the advantages in growing different crops.

5. Discuss the importance of crop rotation in farm management.

6. Explan briefly how crop rotation is practiced on the farm.

7. Can this be simply done on all farms?

8. Name the factors which determine the rotations best suited to any par-

ticular farm. Discuss each point.

9. Under what conditions is it best to allow two or three years before definite

rotations can be fully adopted?

10. How is it best to proceed in planning rotations for a farm already stocked?

11. For a farm intended for stock but not yet stocked?

12. For a grain farm?

13. In truck farming?

14. Discuss the advantages of a rotation chart. Illustrate.

15. Explain the solution to Problem I. Go to the blackboard.

16. Explain the rotation system in Problem II.

17. Explain the reorganization and cropping plans in Problem III.

18. Explain the rotation principle involved in- Problem III.

19. In Problem V, extend the rotation chart over the seventh, eighth, ninth

and tenth years.

20. Suppose in the third year all the clover and alfalfa should winter-kill,

what can be done to meet the situation?

21. Explain a scheme for growing alfalfa in rotation.

22. Plan rotations for a farm with which you are familiar.

CHAPTER XXI

SYSTEMS OF FARMING AND THEIR RELATION TO
SOIL FERTILITY

THE important problem in agriculture concerns the main-
tenance of soil fertility which, in a large measure, determines the
future welfare of a state or a nation. Good farming is commonly
regarded as the proper method wherein soil fertility may be main-
tained, or permanent agriculture established. Does good farming
necessarily mean stock farming?

Systems of Farming. — Three main systems of farming are
recognized, namely: (a) grain farming; (6) stock farming, and
(c) truck farming. Aside from these there are combinations
of two or all three systems. The first two systems are the
most common.

Grain farming, in its strict sense, may be defined as that
system of farming in which crops are raised and sold off the farm.
Crops include corn, small grains, cotton, seeds, etc.

Stock farming consists in the raising of stock. The crops grown
are fed on the farm. The sources of income are stock and animal
products (Fig. 223).

GRAIN FARMING VS. STOCK FARMING

Grain Farming Is Important. — A large percentage of the
farmers in the United States are grain farmers. Many have found
it more profitable than stock raising. A well-balanced national
agriculture demands that a large portion of the farmers be grain
growers, because grains constitute the great source of human foods.
This fact is emphasized the more in densely populated countries,
as in China.1 Furthermore, many more people can be fed on the
grain that can be grown on an acre, for example, than on the
animal products that may be produced when the grain is fed to
livestock.2 It follows, therefore, that the greater the density

1 Farmers of Forty Centuries, by King.

2 It has been roughly estimated that twenty-four per cent of grain is
recovered for human food in pork, about eighteen per cent in milk, and only
about three and five-tenths per cent in beef and mutton. Science, Vol.
XLVI., No. 1181, page 160.

An acre of wheat yielding twenty bushels will furnish more than thirteen
times as much energy as an acre devoted to beef production. — U. S. Farmers'
Bulletin, 877.

343

344

SYSTEMS OF FARMING

of population of a country the greater the necessity for
grain production.

Grain Farming Has Led to Soil Depletion. — It is common
knowledge that wherever grain farming has been practiced exten-
sively in the United States soils have become rapidly depleted.
The growing of wheat in the pioneer days is a good example. It
is for this reason that grain farming is commonly regarded as a
soil-robbing or " soil-mining " enterprise.

FIG. 223. — Stock farming is popular. It puts life into farming.

Grain Farming Revised. — Fortunately, the relation of crop
production to soil fertility is now better understood, so that it is
possible for a grain farmer to realize a profit and at the same time
maintain, and actually increase, the fertility of his soil.

The old system of grain farming consisted in the growing of
one kind of grain after another, or growing the same crop continu-
ously. No effort was made to restore any of the plant-food ele-
ments removed by the crops. The straw was burned because it
was considered of no value, not even as a fertilizer.

Scientific research and good farming methods have taught
that on most soils the nitrogen and organic matter may be main-
tained and increased by practicing a proper rotation including a
legume as a green manuring crop, or including both a green
manuring crop and another legume as a cash crop. The phos-
phorus supply may be maintained by using phosphate fertilizers.
The potassium is given little consideration because most of the
heavier soils are abundantly supplied with this element. When-

MAINTAINING FERTILITY BY LIVESTOCK 345

ever, potassium is deficient, potash fertilizers may be used. More-
over, scientific grain farming demands that all stalks and straw
be returned to the soil. In this manner the draft on the soil supply
of potassium is greatly lessened.

An Ohio Trial in Grain Farming. — At the Ohio Station
the following system of grain farming has been under test for
eight years :

Year 1 — Corn (400 pounds acid phosphate per acre; stalks left on field).

Year 2 — Soybeans for sale as seed (straw returned to the land).

Year 3 — Wheat (300 pounds acid phosphate per acre; straw returned
to land, mostly for corn; wheat seeded to clover).

Year 4 — Clover (plowed under for soil improvement, or first crop cut
and left on ground and second crop cut for seed).

This test is on acid soil limed with pulverized limestone.

This system thus far has resulted in an increase of corn from

49.6 bushels as the average for the first two years (1910-1911),
to 63.5 bushels as an average yield for the seventh and eighth
years. The yield of wheat, likewise, was increased from 29.5 to

32.7 bushels.

Stock Farming Popular. — Stock raising is commonly regarded
as the best system of farming. Grain growers are usually advised
to become stockmen. It is certain that all farmers cannot be live-
stock farmers in the strict sense, because meat and other animal
products can never take the place that grains do in human feeding.

It is generally believed that stock farming is the solution of
the soil fertility problem. This, however, is not an established
fact. It is true, nevertheless, that crop yields are usually better
on stock farms than on grain farms — considering the ways in which
these two systems of farming are ordinarily carried on. This is
because the production of manure in the care of stock has made it
possible for the stock farmer to fertilize his land whether he
believed in soil enrichment or not.

Maintaining Fertility by Live-stock Not Probable. — Accord-
ing to the thirteenth census there is in the United States the eqiva-
lent of one animal of the horse or cattle kind3 to furnish manure
for the maintenance of the fertility of 9.07 acres (farm lands, only,
considered). One cow at best can, on an average, take care of
about two acres a year — considering a three-year rotation
of corn, grain and clover. Under these conditions soil fertility in a
national sense cannot be maintained without the aid of other fertil-

3 When ten sheep or ten hogs are regarded equivalent to one horse or one
cow for fertility maintenance.— Ohio Station Bulletin 328; 1918,

346

SYSTEMS OF FARMING

izing materials. On only a comparatively few stock farms is there
sufficient manure produced by the feeding of the crops raised to
permit the application of about fourteen or sixteen tons of manure
per acre once in three or even four years on all the cultivated fields.
Even when this is done unavoidable losses occur, especially of
phosphorus, which compels recourse to outside sources, particu-
larly the mineral commercial fertilizers.

Grain Farming and Stock Fanning Compared. — Parallel to
the system of grain farming already mentioned, the Ohio Station
is running a system of stock farming in which the same amounts
of acid phosphate and limestone are used and the same crops are
raised. All the crops, except the wheat and whatever clover seed
is produced, are either fed to livestock or passed into the manure
as bedding.4 The manure made each year is applied to the corn
land. These two tests occupy nine acres which are divided into
two parts — one-half of which is farmed in livestock and the other
in grain farming. The experiment is so planned that each crop is
grown every year. The animals are kept in a large box stall,
heavily bedded on a cement floor under cover, so that all manure,
both solid and liquid, is saved and applied to the land in
the spring.

The results for the first eight years are given in the table.
Grain Farming vs. Stock Farming in Maintaining Sort Fertility

Crops

Average Yields per Acre
in Grain Farming

Average Yields per Acre
in Stock Farming

Grain
or Seed

Hay, Stover
or Straw

Grain
or Seed

Hay, Stover
or Straw

Corn
Soybeans. .
Wheat
Clover.. . .

Bu.
58.6

19.0
28.7
Notg

Tons

None harvested
0.87
1.32
athered

Bu.

64.6
21.9
32.4

Tons

1.55
1.00
1.55
2.23

Relative profits were not discussed, since these tests are not
concluded. The amount of labor and equipment required in these
two systems of farming are important factors to be considered in
determining net profits.

At the Illinois Station similar tests have been carried on since
1902.5 The crops grown in rotation, soil treatment and yields
are given in the next table.

4 Ohio Station Bulletin 328.

5 University of Illinois Bulletins 125 and 219 and Circular 193.

NITROGEN AND PHOSPHORUS

' Grain Farming vs. Stock Farming in Maintaining Fertility

347

Soil Treatment

10-year average
1908-1917

7-year
average

6-year
average

Corn

Oats

Clover

Wheat

Alfalfa

No treatment (same rota-
tion)

Bu.
52.6

72.0

73.7
20.3

Bu.
49.3

67.2

66.8
17.7

Tons
1.97

2.30

3.07
0.72

Bu.
21.9

42.5

40.1
19.4

Tons

2.33
3.56

3.58
1.24

Residue,* lime, phosphate
Grain farming
Manure, lime, phosphate
Stock farming
Increase in good farming

* Residue means grain straw, corn stalks, clover straw, chaff, etc.

Lime. — Application of 250 pounds air-slaked lime per acre in 1902; 600
pounds pulverized limestone per acre in 1903; beginning with 1911, pulverized
limestone is added at the average rate of two tons per acre every four years.

Manure is applied at the rate of one ton for every ton of produce.

Phosphate. — 200 pounds of bone meal were applied to the acre annually
up to 1908, then plot was divided and one-half continued to receive bone meal
at the average rate of 200 pounds per acre per year.

To the other half is applied rock phosphate at the average rate of 600
pounds per acre per year.

These results show clearly that a good grain farmer can main-
tain and increase the fertility of the soil.

Combination of Grain and Stock Farming. — The fact that
considerable roughage is produced on grain farms has encouraged
the keeping of more or less livestock to convert this by-product
into useful animal products, and at the same time manure is pro-
duced for use as fertilizer. Thus, roughages of one kind or another
will, no doubt, give the dairy cow and the beef animal especially,
a place in our agriculture for a long time to come.

AN ACCOUNT WITH THE PLANT-FOOD ELEMENTS IN FARMING

Nitrogen and Phosphorus Balance Indicative of Good Farming.

— There are several factors which determine the productive
power of soils. When all other conditions are favorable, how-
ever, the balance of nitrogen and phosphorus in the soil in any
rational system of farming will indicate very clearly the tendency
towards soil enrichment or soil depletion. For example, the draft
per acre on the plant-food elements on a grain farm during a four-
year period when the corn is " snapped"6 and no straw is returned,
may be as follows :

6 When the ears are jerked off the stalks in the field this method of harvest-
ing is called "snapping the corn." The stalks are left in the field.

348

SYSTEMS OF FARMING

Crop

Yield

Nitrogen

Phosphorus

Potassium
Lbs.
11

9
23
46

Corn
Corn .

Bu.

60
50
25
60

Lbs.
54
45
43
56

Lbs.
8

7
7
9

Wheat ....

Oats
Total amount rerr

loved by crops

198

31

89

It isclearthat the above system tends toward rapid soil depletion.

The Balance Shown in a Grain Rotation.— On the other hand,
if a rotation like that mentioned in the Ohio trial were practiced,
the following would represent the exchange of the elements on one
acre during the four-year period (when the composition table
in Chapter VI is used in computing).

Exchange of Fertilizer Elements in Grain Rotation

Removed

Crop

Average
yield

Nitro-

Phos-
phorus
Lbs.

Potas-
sium
Lbs.

Nitro-

Phos-
phorus
Lbs.

Corn

58.6 bu.

53

8

11

Acid Phosphate

49

(700lbs.)(7%P)

Soybeans. . . .

19.0 bu.

7

24

Wheat

28.7 bu.

34

6

7

Clover

113

Clover

2.75 tons

Soybeans *

8

Total for 4-year period.

87

21

42

Total added

121

49

Added

*The nineteen bushels of soybeans will carry about sixty-six pounds of nitrogen, and
the straw about thirty-five pounds, or 101 pounds in the seed and straw. There is also
some nitrogen to be accounted for in the roots and stubble, which, according to experiments,
amounts to about one-tenth of the total amount in the whole soybean plant, or about ten
pounds. In the soybeans on one acre there are contained, therefore, 111 pounds of nitrogen,
of which two-thirds, or seventy-four pounds, are taken from the air. Since sixty-six pounds
are sold in the grain, there are left eight pounds of gain per acre (all straw returned).

The balance in this case shows a gain per acre of about thirty-
four pounds of nitrogen, twenty-eight pounds of phosphorus, and
a loss of forty-two pounds of potassium for each rotation period.

The above system tends to increase soil fertility, as it has been
demonstrated. The loss of ten and one-half pounds of potassium
per acre is small, and can be easily restored, when necessary, by
a little potash fertilizer. No account was taken of the leaching of
nitrogen from the soil.

Increase of Fertility on a Dairy Farm. — The following repre-
sents the losses and gains of nitrogen and phosphorus on one acre
on a dairy farm. A three-year rotation is practiced, manure is

LOSSES IN THE FEEDING TRANSACTION

349

applied at the rate of ten tons per acre once in three years, 300
pounds of acid phosphate per acre are applied with the manure for
corn, and the second growth of clover is plowed under.

Losses and Gains in Fertilizing Elements in a Dairy Farm Rotation

Removed per Acre

Added per Acre

Crop

Yields

Nitro-
gen
Lbs.

Phos-
phorus
Lbs.

Nitro-
Sn
*.

Phos-
phorus
Lbs.

Corn (silage) ....
Oats

12 tons
60 bu.
2.5 tons

82
55.5

16.5
9.5
8.5

Manure (10 tons). . . .

Acid Phosphate
(7% P)
Clover (1 ton)

100.0
41

20.0
21.0

Clover (red) ....
Total

Total

137.5

34.5

141

41

The above system of stock farming tends to increase soil fertility.

Loss and Gain of Plant-Food Elements Illustrated. — In stock
feeding, as in dairy farming especially, considerable feeds are
usually purchased which help to offset the losses. Commercial
fertilizers are often used. Cash crops are often raised. Moreover,
considerable nitrogen may be leached from the soil. It is only
when a farmer understands clearly how the fertilizing elements
may be lost and the sources of gain, that he is able to direct his
farming towards the maintenance of fertility. As it has been
mentioned, the best way to determine this is to study the
crop yields and to note the gain or loss of nitrogen and phos-
phorus, particularly.

The sources of loss and gain to the soil on the farm are illus-
trated in Figure 224.

The losses by leaching concern nitrogen, particularly. Experi-
ments show wide differences in the amount of nitrogen lost in
this manner. On grass lands and on cultivated fields of low
fertility the annual loss per acre is slight; on cultivated fields of
moderate fertility the loss is about twelve to twenty pounds per
acre per year in regions having thirty inches of rainfall; and on
cultivated fields heavily manured, or in a high state of fertility,
the annual loss per acre may approximate forty pounds when the
rainfall is heavy during July, or the middle of the growing period.
The annual loss of nitrogen by leaching from uncropped or bare
fields may exceed 150 pounds per acre.

Losses in the feeding transaction include the elements retained

350

SYSTEMS OF FARMING

by the animals for milk production, growth, etc., and the unavoid-
able losses sustained in handling the manure. When the manure
is given the best care that can be given it under ordinary farm
conditions, these losses may be estimated at forty per cent for
nitrogen which is contained in the feeds fed, thirty per cent for
the phosphorus, and about twenty per cent for the potassium.
When the manure is left exposed to rains in an open yard even for
three months, these losses may run as high as fifty-six per cent for
nitrogen, forty-six for phosphorus, and seventy-one for potassium.

Feed i no Transact lot

. (Nitrogen - about 40
LOSS of < Phosphorus -about 30
(.Potassium- about 20'

Loss of N. P, K in crops sold

FIG. 224. — Diagram illustrating the sources of loss and gain of the fertilizing elements

in farming.

In bedding no losses are to be considered except when manure
is carelessly handled.

It is possible for a good stock farmer to return to the soil
about seventy per cent of the fertilizing elements contained in the
feeds fed and in the bedding.

Fertilizers may be applied directly to the soil or mixed with
manure, as in case of phosphates.

When feeds are purchased the manure is enriched by an amount
equal to the fertilizing elements contained in the feeds minus the
losses in the feeding transaction.

Summary of Losses and Gains. — The sources of loss and gain

DETERMINING THE LOSSES AND GAINS 351

of the soil supply of the important plant-food elements may be
briefly summarized as follows:

How losses occur:

(a) In the sale of crops

(6) In the feeding transaction.

(c) Leaching from the soil — nitrogen particularly

(d) Soil erosion
Sources of gain:

(a) Feeds purchased
(6) Fertilizers purchased

(c) Nitrogen fixation, especially by legume bacteria 7

(d) Bedding purchased, particularly straw 8

Determining the Losses and Gains. — When the manure pro-
duced is well cared for and all straw and other material like clover
chaff and uneaten shredded corn stalks are passed into the manure
as bedding, the approximate losses and gains of the plant-food
elements, particularly nitrogen and phosphorus, may be ascer-
tained. In constructing the balance sheet, the following rules
should be observed :

1. The amount of nitrogen, phosphorus and potassium con-
tained in any crop sold, except the nitrogen in legumes sold, is to
be considered lost to the soil on the farm. (Consult the composition
table, Chapter VI, and also the table on page 393, for the
amount of the fertilizing elements contained in crops and feeds.)

2. Losses sustained in the feeding transaction may approxi-
mate forty per cent of the nitrogen, thirty per cent of the phos-
phorus, and twenty per cent of the potassium contained in the
feeds used.

3. The nitrogen in clover and alfalfa hay sold is to be regarded
neither loss nor gain to the soil.

4. Losses in pasturing may be considered as follows: Nitrogen,
thirty per cent; phosphorus, fifty per cent, and potassium,
twenty per cent. (Good pasture may be considered the equivalent
to the production of one and one-quarter tons of mixed grass
hay per acre.)

5. Loss in leaching may be considered at twelve to twenty
pounds of nitrogen per acre per year on cultivated fields of moder-
ately rich soil in humid regions, and about forty pounds per acre
on heavily manured fields or on soils of very high fertility , and under
heavy rainfall, especially during the middle of the growing period.

7 A small amount of nitrogen is washed from the atmosphere as ammonia.
This amounts to about five pounds per acre per year.

8 Shavings possess little or no fertilizing value.

352

SYSTEMS OF FARMING}

6. The fertilizing elements contained in purchased feeds fed
minus the loss in feeding is to be regarded as gain to the soil.9

7. The nitrogen in clover, alfalfa and other legumes fed on the
farm minus the loss in feeding is to be regarded as gain to the soil.

8. The nitrogen in clover, or other legume plowed under, is
to be regarded as gain. (Estimate yields in terms of hay.)

9. The fertilizing elements contained in straw purchased for
bedding are to be regarded as gain.

10. The fertilizing elements contained hi fertilizers purchased
are gain.

The Nitrogen-Phosphorus Balance Sheet. — The application
of these rules can best be illustrated by the following problem:

On a dairy farm of 120 acres the following crops are grown:

Crops

Acres

Average Yield per Acre

Corn
Oats

25
25

12 tons silage, 65 bu. corn
50 bushels

Clover (medium red)

15

2 tons (1 cutting)

Alfalfa

10

Q/2 tons (3 cuttings)

Pasture in rotation
Barley

25
10

Equivalent to 1M tons mixed grass
hay per acre
30 bushels

All the milk produced is sold.

All crops harvested, except the barley, ten tons of clover hay and 250
bushels of oats, are fed on the farm.

Manure is hauled directly to the field or stored in a manure shed when it
cannot be hauled directly to the fields.

Two hundred fifty bushels of oats and all the barley are sold.

Ten tons of clover hay (red clover) are sold.

Seventeen acres of corn are made into silage.

Eight acres of corn are shredded. About one-half the shredded stalks
is used for bedding.

All straw is used for bedding.

The second growth of clover is plowed under (equivalent to one ton of
hay per acre).

Ten tons each of wheat bran and gluten feed (high grade) are purchased
and fed annually.

Three hundred pounds of acid phosphate (seven per cent phosphorus)
are applied per acre to the corn land.

Determine the annual loss or gam of nitrogen and phosphorus in this
system of fanning.

9 When the skim milk is fed on the farm it should be considered as pur-
chased feeds, since the losses in the feeding transaction include milk production.

CONCLUSIONS

353

The balance sheet may be constructed as follows:

The Nitrogen-Phosphorus Balance Sheet

Nitrogen Balance Sheet

Phosphorus Balance Sheet

Crops, Feeds and
Fertilizers

Loss of
Nitrogen

Gain of
Nitrogen

Loss of
Phosphorus

Gain of
Phosphorus

Corn silage (204 T.) (Rule 2) .

555.0

84.5

Corn (520 bu.) (Rule 2)

188.0

26.0

Shredded corn stalks (7 tons

fed) (Rule 2)

52.5

....

8.0

Oats (1,000 bu. fed) (Rule 2) .

253.5

34.0

Oats (250 bu. sold) (Rule 1) . .

158.5

28.0

....

Clover hay (20 tons fed)

(Rules 7 and 2)

492.0

20.5

Clover hay (10 tons sold)

(Rules 3 and 1)

34.0

Clover plowed under (15 T.)

(Rule 8) ....

615.0

Alfalfa hay (45 tons fed)

(Rules 7 and 2)

1285.0

63.5

....

Pasture (Rule 4)

229.6

....

49.0

....

Barley (300 bu. sold) (Rule 1).

265.0

53.0

Wheat bran (10 tons fed)

(Rule 6)

307.0

180.0

Gluten feed (10 tons fed)

(Rule 6)

487.0

38.0

Acid phosphate (7500 Ibs.)

(Rule 10)

525.0

Leaching (corn land) (Rule 5).

300.6

Totals

2001.5

3186.0

400.5

743.0

Net loss or gain

1184.5

342.5

This system of farming tends towards soil enrichment and
the increasing of soil fertility. The crops grown also indicate
this tendency.

The potassium balance sheet may be worked out in a similar
manner as that for phosphorus.

Conclusions. — Good farming may be either stock farming or
grain farming. It is possible to increase and maintain soil fertility
under either system. The crop yields and the nitrogen-phosphorus
balance sheet in any rational system of farming may indicate
whether the system tends towards soil depletion or soil enrichment.

Fertility Surveys. — Make surveys of a number of farms of the region
including farms of different types. Obtain data to calculate the amounts of
plant-food elements removed by the chief crops and also the amounts returned
in green manure, barnyard manure, etc. Make comparative studies of these data
and determine what types of farming are best for maintaining the soil fertility.

Home Projects in maintaining the soil fertility with any of the permanent
lines of farming may be started.

23

354 SYSTEMS OF FARMING

QUESTIONS

1. What is the important problem in agriculture? Why?

2. Name and describe briefly the different systems of farming.

3. What is the importance of grain farming?

4. What has been the result of grain farming in the past? Illustrate.

5. How is it possible, even in grain farming, to maintain and increase soil

productivity? Give an illustration.

6. Why is livestock farming popular?

7. What are the probabilities of maintaining soil fertility by livestock farming?

8. What comparisons have been made between livestock farming and grain

farming? Describe these tests briefly and give results.

9. What are the advantages to be gained in combining stock raising with

grain growing?

10. Aside from crop yields, what may indicate good farming as regards soil

fertility? How can this be determined on different fields?

11. Explain and illustrate by aid of a diagram the sources of loss and gain of

the fertilizing elements in farming.

12. Summarize the sources of loss and gain of the soil supply of plant-food

elements in farming.

13. How may the losses and gains be determined in the following cases:

(a) When corn or barley is sold.

(6) When clover or alfalfa hay is sold.

(c) When alfalfa hay is purchased and fed.

(d) When soybean seed is sold.

(e) When straw is purchased for bedding.

(/) When corn silage is produced and fed on the farm.

(g) When commercial fertilizers are applied to the soil.

(h) Leaching from the soil.

(?') When a crop of green clover is plowed under for soil improvement.

(j) When the straw produced is used for bedding.

(A;) When stock is pastured.

(I) When concentrates are purchased and fed.

(m) When clover hay is produced and fed on the farm.

14. Give the important conclusions of this chapter.

PROBLEMS

1. When the manure is well cared for, how many tons of wheat bran or
cotton-seed meal must be fed to offset the loss of phosphorus in feeding twenty
tons of alfalfa and sixty-five tons of corn silage?

2. Assuming good care in handling the manure, construct a nitrogen-
phosphorus balance sheet for a farm on which all the crops, except cabbage,
are fed — as follows: No feeds are purchased; 250 tons of corn silage are fed
(all corn made into silage) ; sixty tons of clover hay (medium red) ; six tons of
oat straw are fed, the remainder is used for bedding; 1000 bushels of oats;
thirty acres of pasture equivalent to 0.8 ton of mixed grass hay per acre;
eighty tons of cabbage are sold, (a) How many pounds of acid phosphate
carrying sixteen per cent phosphoric acid (P2 O6) must be used to offset the
loss of phosphorus? (b) How many pounds of rock phosphate analyzing
13.5 per cent phosphorus?

3. Suppose on a stock farm the following crops were fed: Twenty acres
of corn yielding twelve tons of silage per acre, forty acres of medium red
clover, yielding two tons of hay per acre, and 19.2 acres of oats averaging
fifty bushels per acre (all straw used for bedding). Ten tons of gluten feed
(high grade) were purchased and fed. Assuming good care in handling the
manure, what per cent of the fertilizing elements contained in the crops and
purchased feed may be regained in the manure?

CHAPTER XXII

HOW THE NEEDS OF SOILS MAY BE DETERMINED

Chemical Analysis Has Limitations. — At first thought it would
seem that since the requirements of the different crops are known,
the fertilizer needs of any particular soil can be determined simply
by a chemical analysis of that soil. This, however, is not the case,
because several factors must be considered in addition to the
quantity of the plant-food elements contained in the soil — such
as, the plant characteristics, the kind of soil, availability of the
elements, and all the other factors which determine fertility.

What might be the fertilizer needs of a particular soil which
analyzes 0.3 per cent nitrogen, 0.08 per cent phosphorus, 1.3 per
cent potassium, and is not acid? 1 No one can tell with any degree
of certainty without considering carefully all the factors named
and to which reference is made (p. 80). It is evident, therefore,
that the chemical analysis of a soil has certain limitations. It is
not to be understood, however, that chemical soil analyses are of
no value. Because of these limitations, other methods than
determining the total amounts of nitrogen, phosphorus, and potas-
sium in soils have been devised to ascertain the fertilizer needs
or the cropping possibilities of soils; such as, availability tests,
pot tests made in the greenhouse, cylinder tests made indoors
or out of doors, and fertilizer tests made on the farm under
field conditions.

Other Factors First. — Before deciding upon a chemical analysis
to solve a soil fertility problem, the following factors should
be considered:

(a) Drainage. — Very often crop yields are low, or some crop
fails entirely, because of the lack of proper underdrainage, even
though the soil may be rich in all the elements. This factor should
be considered on sloping fields, on hillsides and at the foot of
slopes or hills as well as on lowlands (Fig. 46, Chapter IX).

(6) Moisture Supply. — Frequently the lack of sufficient mois-
ture, even in humid climates, is the cause of low yields. This
lack of moisture may be the result of insufficient rainfall during

1 This particular soil responded well to acid phosphate and potash in
the field.

355

356 HOW THE NEEDS OF SOILS MAY BE DETERMINED

the growing period, and especially because of gravel or coarse
sand subsoils (Fig. 42) .

(c) Physical Condition of the Soil. — Since there is a close
relationship between the physical condition of a soil and its
fertility, attention should also be given this factor in diagnosing
infertility or the cause of low yields. A striking difference in
growth of plants due to physical improvement of the soil is shown
in Figure 225. Cultivation improved the poor growth as shown
by Figure 226.

(d) Inoculation. — In determining the cause of failures or
unsatisfactory crops in growing any legume, especially for the
first time, it is important to determine whether or not the soil is
properly inoculated. This can best be done by digging up several
plants with a spade arid examining the roots for nodules. If none
are found and the soil is not acid, the lack of proper organisms
must necessarily be the limiting factor, provided, of course, other
conditions are favorable. If the soil is acid, liming is the first aid,
then inoculation (see index).

(e) Harmful Agents in the Soil. — Not only should injury from
diseases like rust, barley stripe and blight, and from insects like
leaf aphids, boll-weevil and beetles be considered, but also the
harmful agents which may infest the soil. These may be diseases,
insect pests, certain poisonous substances, etc. (Chapter XIV).

(/) Organic Matter. — Organic matter (see index) in soils affects
practically all the factors which determine fertility. It is important,
therefore, to note the amount of organic matter in any soil under
examination, especially upland soils. The color of the soil usually
indicates the amount present.

CHEMICAL ANALYSES AND THEIR VALUE

Total vs. Available Plant-food Elements. — Chemical analysis
which shows the total quantity of the important plant-food ele-
ments contained in a soil is not always an index to its productive-
ness, because it is not so much the total supply as it is the amount
that is available, or which can easily become available to meet
the needs of the crop, that determines the productivity of the
soil. When this fact became established, chemists tried to dis-
cover some method to measure the availability of the elements,
or ascertain to what extent the crop can secure its requirements
from any particular soil. Attempts, therefore, have been made
to imitate the action of the plant roots in securing the elements,

TOTAL VS. AVAILABLE PLANT-FOOD ELEMENTS 357

FIG. 225.—' Not a fertilizer test — only a difference in plowing To left, clover sod was
fall plowed as in Figure 75. To right, same kind of plowing but done in the spring. To
left, nitrification was retarded. (See Fig. 226.)

FIG. 226. — Proper cultivation overcame conditions shown in Figure 225. No difference
in yield at harvest time.

358 HOW THE NEEDS OF SOILS MAY BE DETERMINED

but little progress has been made. Some of these methods,
however, have come nearer than the total analysis in ascertain-
ing the cropping possibilities of a soil, or in determining its
fertilizer needs.

Uses for Chemical Analysis.— Soil fertility investigators and
field men usually prefer to know the chemical composition of
the soils on which they work. In this respect, chemical analyses
are of great value, especially in continued experiments, in studying
the effect that certain methods of fertilization and cropping have
upon the chemical properties of a soil, or upon the supply of the
plant-food elements.

In soil survey, chemical analyses are especially valuable in
comparing soil types and in tracing any correlation between the
chemical and physical properties of certain types.

Frequently, farmers desire chemical analyses of soils in order
to determine their quality as compared with other soils.

Four things are commonly determined by chemical analyses,
namely: (a) the need of lime; (b) the supply of nitrogen and
organic matter; (c) the phosphorus supply, and (d) the potassium
content.2

Testing Soil for Its Need of Lime.— Since an acid soil is detri-
mental to economic crop production, testing a soil for acidity
or for its need of lime is of primary importance. Some farmers
have limed certain soils because they thought they were acid,
when, later on, tests showed that no lime was needed. This
represents a typical case of wasted energy and money because of
guesswork. Many farmers have failed again and again trying to
grow alfalfa on acid soils, all because they did not consider the
necessity of determining beforehand whether or not the soils were
adequately supplied with lime. Again, many farmers do not know
whether it would be best to lime their soils or not. Simple acidity
tests can answer such questions definitely (p. 234).

2 Trustworthy samples for full chemical analyses should be collected by
trained men. A soil auger is commonly used in getting the samples. At least
ten different borings from different parts of the field examined should consti-
tute the sample to be taken into the laboratory. Samples of the surface soil
are usually taken to depths of six and two-thirds to eight inches. The subsoil
should be examined to a depth of at least three to four feet for texture, struc-
ture, permeability to water, etc. For practical purposes it is not necessary
to make chemical analyses of subsoils.

When the soil sample reaches the chemical laboratory, it is air-
dried, screened of its stones, coarse gravel, etc., thoroughly mixed and
finely pulverized.

PHOSPHORUS DETERMINATIONS 359

Nitrogen and Organic Matter. — Nitrogen is an index to the
supply of organic matter. When the percentage of nitrogen is
high, the organic matter is abundant; when very low, the need of
organic matter becomes evident. Many highly productive silt
loams, for example, contain 0.25 per cent and more of nitrogen,
while many others, particularly the lighter-colored types, contain
about 0.15 per cent. Frequently the nitrogen content of certain
long-cropped silt loams is as low as 0.09 per cent. Such a low
percentage, together with field observations, generally indicates
the urgent need of more nitrogen and organic matter. Thus,
special manuring may be recommended, the plowing under of
some legume as a green manuring crop, and the growing of more
and better clover. Whenever possible, it is instructive to compare
the nitrogen content and organic matter of any long-cropped soil
with a virgin sample of the same soil collected along the fence.
Such comparisons usually support the reasons commonly given
why crop yields are much less now than in former years.

Phosphorus determinations are not only interesting but of
much value, since this element is regarded by many as the key to
the maintenance of soil fertility. Highly productive silt loams
commonly analyze 0.09 to 0.12 per cent, or more, of phosphorus.
Some long-cropped silt loams contain no more than 0.03 per cent.
Practically all low determinations of phosphorus indicate the need
of phosphate fertilizers. When examining into the phosphate
needs of any particular soil, it is also important to take into con-
sideration soil acidity, the fertility factors, the cropping history
of the fields, and the character of the crops grown.

Some silt loams, for example, are comparatively well supplied
with phosphorus, as high as 0.08 per cent, but because they are
deficient in active organic matter, or because of poor aeration,
they respond to soluble phosphate fertilizers (Fig. 126). Again,
most acid, black silt loams are in need of phosphates even though
they may contain fairly good supplies of phosphorus (see index)
(Fig. 137).

It is important to know that certain soils are well supplied
with phosphorus, because this fact will decide whether it is neces-
sary to rely wholly upon commercial fertilizers for the source of
phosphorus, or to adopt such measures as to render available the
phosphorus already present in the soil. During the improvement
of such soils by the addition of organic matter and by liming,
it is usually necessary to supply available phosphorus in the form

360 HOW THE NEEDS OF SOILS MAY BE DETERMINED

of acid phosphate or bone meal. Later on rock phosphate may
be used.

Phosphorus determinations of ordinary sands, mucks and peats
are valuable in ascertaining the quality of these soils.

If any one doubts that a soil can ever become depleted by
exhaustive cropping, let him compare the phosphorus analyses of
long-cropped and depleted lands with those of virgin soils of the
same kinds, or of similar soils that have had their phosphorus
supplies maintained or increased through good farming methods.
No arguments are so convincing.

Potassium Analyses. — On many soils, especially the heavier
types, potassium determinations are important largely because
of their inventory value. On other soils analyses show surprisingly
low supplies of this 'element, particularly in case of peats. Usually,
when a soil is found to contain a low amount of potassium, potash
fertilizers are required. Soils abundantly supplied should be so
managed as to enable them to render available sufficient amounts
to meet the needs .of crops (see "Potash" in index).

POT TESTS

Pot Tests Not Fully Reliable. — It has been the hope of chemists
to determine by pot tests what chemical analyses do not or can
not show as regards the fertilizer needs of a soil or its cropping
possibilities. This method consists in filling several jars or cylinders
with the soil to be studied, treating the pots in different ways,
and growing a crop to indicate the proper treatment (Fig. 192).

This method seems most reasonable and sure. Moreover, it
can be carried on under absolute control as regards moisture and
temperature conditions. The results of some pot tests are of special
value in determining the fertilizer needs of any particular soil
and serve to reinforce field observations and chemical analyses
(Figs. 135 and 136). In general, however, such results can not be
fully relied upon as guides in the practical operations of the farm,
because it is impossible in such tests to reproduce the natural
conditions found in the field.3

FIELD OR PLOT TESTS

Field Tests Are Best. — Fertilizer tests made on the farm, or
on the land in continued plot experiments, are the most reliable.

3 Tests made in large cylinders usually extend over several years. It
is not practicable to make pot tests on the farm.

FIELD TESTS ARE BEST 361

/ _ No treatment

2 Acid

5 Muriate of \ potash

4- A/o treatment

<S _ Aiitrate. of \&oda

£ _ Acid phosphate and\ nitrate, of

7 _ A/o treat \nent

S^ _ AiCld phosphate. ana\ muriate. o

? _ Muriate of potash and Citrate of

/£ _ /Vb tre at m ent

// Acid phosphate j potash, land nitrate o-f

/£ Acid phosph&f'e, pofasH, <and nitrate of

/J _ /Vb treatment

14- 'Fhosphafe , pota&h and \nifraie of so da ^ com

_/£ _ ^ _ » _ " i " '» » " wheat
/* A/o treat be- nt

n Some <?a // hut more, pho&phgte and" /e&s nitrates
// Manure. , $ tons, on , corn an

No,

2o Manure > -4- tons on\corr\

22 No

b/ood

2.4 Same as /?, but nitro'q <sn /n Sulphate ammon/a
_*£ A/o treatment

27 S^?»»(? as 17 but fiiffoqen in n/firate of //'

A/o

Lime.. A/O ///»<2.

FIQ. 227.— A aeries of experimental plots. (Ohio Station.) (See Fig. 229.)

362 HOW THE NEEDS OF SOILS MAY BE DETERMINED

In scientific studies, it is necessary to extend the tests over many
years before accurate results can be obtained regarding the
proper soil treatments and the maintenance of fertility. Such
scientific work is much more difficult than ordinary chemical
analysis or pot tests.

How Experiment Stations Conduct Tests. — Nearly all of the
Agricultural Experiment Stations are conducting field tests, some
of which are very extensive. The size of the individual plots is

usually one-tenth of
an acre, each carefully
measured and perma-
nently staked. Figure
227, representing one
of the many series of
plot tests established
by the Ohio Station,
illustrates how this
work is done.

This particular
group of plots repre-
sents block D in
Range IX on the east
side of the Central
Farm at Wooster,
Ohio. Block D is one
of five in an experi-
ment begun in 1893,

FIG. 228.-A small plot left unlimed as a check. tO determine the effect

of fertilizers and lime

on corn, oats, wheat, clover and timothy in a five-year rotation.
It is to be observed that each block consists of thirty plots,
each sixteen feet wide and sixteen and one-half rods long. The
soil treatments are indicated in the diagram. The west half
of each block, or of each plot, is limed, while the east half is
left unlimed. The results are secured by harvesting the crop
on each plot separately. The yields are carefully determined and
recorded (Fig. 229).

How Farmers Can Conduct Field Tests. — The farmer is a
busy man and therefore has not the time to devote to much
experimental work. That is the business of the Agricultural
Experiment Stations. But the Experiment Station can not do

HOW FARMERS CAN CONDUCT FIELD TESTS 363

364 HOW THE NEEDS OF SOILS MAY BE DETERMINED

everything. The best it can do on soil problems is to establish
certain fundamental principles that may be applied generally.
The simpler problems and those which have to do with the soils
on individual farms are left to the leading farmers to work out
either for themselves, or under the direction and supervision of
the Experiment Station, the College of Agriculture, or of the
County Agricultural Representative. Such tests can be made
simple, and need not interfere in any way with the farmers' plans.
A few illustrations follow:

Testing the Value of Agricultural Lime. — Even though the
Experiment Stations have proved the value of liming acid soils,

Fence

1

i

> No phosphate

-

T~t

<!

> Phosphate

FIG. 230. — How to demonstrate the value of lime and acid phosphate. (See page 232.)

it is important to continue to demonstrate the value of agricultural
lime on individual farms and on different soils. Such tests are
valuable, not only from an educational point of view, but, when
rightly conducted, afford the farmer a basis for figuring the in-
creases in net returns from this method of soil improvement.

When an entire field is to be limed, an acre strip, or a one-half
or a one-fourth acre area, may be left unlimed (Fig. 228). When
only a small area is to be limed as a trial, the limed strip may
extend through a field or project into it; or a portion of a field
may be limed. Both limed and unlimed areas should be cropped
the same, the same quality of seed used, and the lots should receive
like treatment, except for the lime (Figs. 229 and 230).

Trying Fertilizers. — In trying fertilizers, it is comparatively

HOW FARMERS CAN CONDUCT FIELD TESTS 365

easy to fertilize a strip through the center of a field, or to leave
an unfertilized area for comparison. When fertilizers are used in
the drill for corn, for example, a few rows could be left unfertil-
ized (Figs. 133 and 137).

Sometimes the problem is to determine the proper combina-
tion of fertilizers or which are the best to use. It then becomes
necessary to make a more elaborate test. Figure 225 represents a

Muriate of potash, 200 I bs. per acre /\

Muriate of potash, 200 Ibs. per acre D

Acid phosphate, 400 Ibs. per acre

No treatment (check) C

Muriate of potash, 200 Ibs. per acre
Rock phosphate, 800 Ibs. per acre

Manure, 25 tons per acre

FIG. 231. — Diagram of a manure and fertilizer test made on a marsh soil. (See Figs.
132, 232, and 233.)

test made on a marsh area in Wisconsin. Four different treat-
ments were compared. Each strip represents one-quarter of an
acre. Figure 226 shows the results secured on plots A and B.
Figures 232 and 233 combined, compare the results of B with no
treatment C. Figure 233 shows the results on plots C and D;
and Figure 132 shows the results on D and E.

Similar tests may be made on sands and on other upland soils.
When the soils are acid, one-half of each fertilized plot or a portion
of each end, should be limed, so that results may be secured both
with and without lime.

366 HOW THE NEEDS OF SOILS MAY BE DETERMINED

Points to Observe. — In making liming tests, best contrasts
in results can be secured when a definite line is made between
the "limed" and "no lime" areas. To accomplish this, the west
portion of a field should be limed when the wind blows from the
east, or the east portion when the wind blows from the west. When
the limed plot extends through a field, the windward border of
the plot, at the time the lime is applied, should be selected for the
best contrasts. The same point should be observed in applying
certain fertilizers broadcast.

Sometimes when two or more adjacent plots are to be fertilized
differently, it becomes necessary to mix certain of the fertilizers

^

. POTASH
ACID PHOSPHATE

IPl

FIG. 232. — Potash alone compared with potash and acid phosphate. (Wisconsin Station.)

with moist soil to prevent the wind from blowing the fertilizer
over the other plots. In such tests it is usually best to apply
the fertilizers by hand, and then mix them thoroughly with the
soil by disking or "dragging."

Avoid the laying out of test plots adjoining and parallel to
fences. Extend them into or through the field away from fences.
Long strips are better than square plots.

Observing the difference in growth on the various plots is not
sufficient in determining the final and comparative results. It
is always best to obtain the results by weighing the whole crop and
determining the actual yields. When it is not convenient to
harvest each plot separately, the crop on an average square rod
on each plot may be properly harvested, and results calculated
to acre basis.

POINTS TO OBSERVE

367

368 HOW THE NEEDS OF SOILS MAY BE DETERMINED

FARM EXAMINATIONS

Farm Visits Are Essential. — Whenever a farmer wishes definite
information concerning the needs of his soil, drainage, crop rota-
tion, etc., it is most satisfactory, if such provision is made, for a
representative to visit the farm. In this way a soil fertility expert
is able to consider all conditions, note the character of the subsoil,
observe the growing crops if circumstances permit, obtain the
cropping history of each field if necessary, and if he thinks it
important, take samples of soil for chemical analyses. The
farmer should receive a report with recommendations for soil
improvement. When several farmers in a community become
interested in such farm examinations it is often advisable to
" follow up" or reinforce such work with field demonstrations.

Field demonstrations may be conducted as home projects to determine
the values of each of the methods of soil improvement which are considered
profitable. These may include projects in liming, inoculation, green- manuring,
use of barnyard manure, use of commercial fertilizers, drainage, irrigation,
subsoiling, dry farming methods, mulching, etc. In each trial check plots
should be left for contrast. This will make the trials more conclusive.

Consult chapters XII and XIII.

QUESTIONS

1. Can the fertilizer needs of a soil or its cropping possibilities be determined

by chemical analysis? Explain.

2. What other methods have been devised to answer these questions?

3. Name and discuss the conditions which should be considered before

deciding upon chemical analysis for the solution of a soil fertility problem.

4. State specifically how organic matter in soils affects the fertility factors.

5. Why were methods of chemical analysis devised to determine the availa-

bility of the elements? What success has been attained?

6. In general, mention some benefits to be derived in determining the total

amount of each of the important elements contained in soils.

7. For practical purposes, what analyses are commonly made? Discuss the

value of each determination.

8. Discuss the results secured in pot tests in relation to practical operations

of the farm.

9. How are pot tests usually made?

10. What is the best method whereby the fertilizer needs of soils may be

determined and principles governing fertility maintenance established?

11. How do experiment stations conduct such tests?

12. Explain how farmers can conduct simple lime and fertilizer tests.

13. Mention some points to be observed in making these tests.

14. Discuss the advantages in having the soils examined on the farm by a

soil fertility expert.

CHAPTER XXIII

PROFITABLE CROP PRODUCTION

Large Crops Not Necessarily the Most Profitable. — It is
commonly assumed by farmers that large crop yields per acre are
the most profitable, and that he who raises the most per acre
makes the most money. This may or may not be true. High
yields per acre are profitable when consistent with low cost per
unit of produce. Low-priced land, rich, virgin soil, favorable
seasons and cheap labor are important ^actors which lend to such
possibilities; but ordinarily the general principle is that the higher
the yield on a given soil, the greater the cost per acre. The product
per dollar of expense will usually increase up to a certain point
as a result of increased expenditures per acre, but a point is certain
to be reached with continued increase of expenditures when the
returns per dollar will be less and less.

On high-priced land excessively fertilized a yield of 120 bushels
of shelled corn per acre may be just as unprofitable as a yield of
twenty-six bushels on land never fertilized. In the first case,
expensive and excessive fertilizers may swallow all profits, while
in the second case the yield may not be sufficient to pay for the
labor and machinery costs.

Profitable Crop Production Is the Foundation of Successful
Farming. — It is very necessary, therefore, for every farmer, if
he wishes to put his farming on a money-making basis, to produce
a large enough yield to cover all production costs and have net
profits besides. The net profits per acre, of course, should be as
large as possible if thechange in method does not reduce the number
of acres the farmer can raise. Increasing the yield on a given
soil also means increasing the expenses per acre in producing the
crop, though at the same time the profits may be increased.
Doubling the yield may not necessarily mean doubling the profits;
but, on the contrary, it may reduce the profits. It is not so much
a question of maximum yields, therefore, as it is a question of
maximum profits in crop production which, in a large measure,
determines successful farming.

Profits Determine Fertilizer Practice. — In fertilizer practice
and in soil improvement, the question arises, "Does it increase
24 369

370 PROFITABLE CROP PRODUCTION

the farm profits?" Few farmers, indeed, could be induced to use
fertilizers and agricultural lime were no profits forthcoming. It
is quite evident that when crop increases are profitably obtained
by improving the soil through fertilization and otherwise, the farm
profits, or managerial income,1 should likewise be larger. Much,
of course, depends upon the manner in which the crops are disposed
of. This explains why soil fertility investigators extend their
investigations into farm management just so far as to enable
them to arrive at their conclusions by determining the "value of
crop increases above cost of fertilizers."

Commercial fertilizers are profitable when they are judiciously
used. The fertilizer practices in the Eastern and Southern states,
as well as in the countries of the Old World, are sufficient evidence
of this fact.

The Crop-production Problem. — A most rital problem which
confronts the land owner in his farm management is to determine
the point at which his crop yields are the most profitable. To do
this he must consider such factors as the value of his land,2 the
cost of labor, machinery cost, cost of fertilizers and the price he
expects to receive for his produce. In such determinations the
cost of fertilizers is an important factor, because the fertilizers
may be largely responsible for high yields and at the same time
lower, or even consume the profits, if excessively or unwisely used.

In a certain corn contest a boy won the prize because he pro-
duced the greatest number of bushels per acre. However, when
the total cost was considered, the value of the crop at market
price was not sufficient to cover the cost. The largest item was
the cost of the fertilizer treatments — he fertilized excessively.

The Value of a Plot Left Untreated.— The actual profits
derived through the use of commercial fertilizers on the farm are
too frequently matters of guesswork. A check on increases due
to fertilizers may be secured by comparing fertilized plots with a
plot left unfertilized. It is just as important that leading farmers
establish test plots on the farm to determine economic crop pro-
duction as it is for experiment stations to do so — the only difference

1 Managerial or labor income means farm profits above total costs; total
costs including unpaid family labor and interest on total investment. Family
labor means all work done by wife and children on the farm, not including
the household.

2 Land rental is an expense considered in crop production. When the land
is owned by the farmer it is usual to charge five per cent on the value of the
land in lieu of rent.

DETERMINING THE MOST PROFITABLE FERTILIZER 371

being the farmer's system should be much more simple
(Chapter XXI).

Determining Profits From Fertilizers. — The almost universal
method of interpreting fertilizer tests is to subtract the cost of
fertilizer from the increased value of the crop. If the value of
the increase is greater than the cost of the fertilizer, the fertilizer
is considered profitable. Authorities on farm management and
agricultural economics criticise this method because all the other
costs, such as interest, hauling and applying fertilizers, and har-
vesting, storing and marketing the increased crop, are disregarded.3
All authorities would not count interest on " materials in process,"
such as fertilizers and feeds.

Since profits determine fertilizer practice, it is quite necessary
to give business interpretation of results of fertilizer tests. Net
value of the crop increase, therefore, should determine the conclu-
sions regarding profits from fertilizers. A check plot is necessary
to obtain the increased value of the crop. The value of the increase
minus the increased cost for fertilizer and additional labor, etc.,
gives the net value of the increase. In all liberal fertilization it
is usually best to obtain the net value of the increases for the rota-
tion rather than for one year only.

When the increase in yield gives only a small margin above
the mere fertilizer cost, the chances are the cost of application
and other increased costs would cancel this margin.

An Example. — On a soil deficient in available phosphorus, a
farmer applied 300 pounds of acid phosphate per acre for oats in a
three-year rotation of oats, clover and corn. A plot was left
unfertilized for a check. The increases per acre in three years
were seventeen bushels of oats, one-half ton of clover hay and ten
bushels of corn, the total valued at $22.50 (including straw and
stover). The cost of fertilizer, interest, application and all other
costs to harvest and care for the increase was calculated to approxi-
mate $9.00 for the three years. In this case $13.50 is the net
value of the increase per acre. These results clearly show that
acid phosphate was profitable.

Determining the Most Profitable Fertilizer. — Frequently on
lands in need of fertilizers, it becomes necessary to determine by
field tests which of two or more fertilizers, combinations of fertil-
izers or different amounts applied is the most profitable. The net

3 Warren, Farm Management.

372 PROFITABLE CROP PRODUCTION

value of the increased yield for each fertilizer treatment must
necessarily be obtained in a similar manner as described in the
foregoing paragraphs.

Basis of Computing Returns. — The following questions now
arise: " Upon what basis should the profits be computed? Should
the profits be expressed in terms of per cent of the cost of the fertil-
izer, or should they be expressed in terms of net profits per acre? "

In all farm accounting, the cost of fertilizer is considered an
expense and is charged against the crop. To be consistent, this
expense should not be considered as capital permanently invested.
The two main benefits derived through proper fertilization are :
(a) the productivity of the soil is increased, and (b) the soil
reserve of some of the important elements of plant-food is increased
or maintained. These benefits result in an " appreciation " which
is an increase in the value of the land.

Moreover, expressing profits in terms of per cent on money
paid out, or invested, is deceiving. Some business men have gone
into bankruptcy because they relied too much upon what per
cent seemed to show. In business administration it is recognized
that actual profits above total costs determine which of two invest-
ments or business ventures, for example, is the more profitable.
An Example .-"A." gamed a net profit of 400 per cent on money
he invested. "B" gained a net profit of ten per cent. This does
not necessarily mean that "A" made the more profitable invest-
ment. "A" had one dollar of ready money and invested it in
popcorn, and in so doing gained a net profit of four dollars. "B,"
on the other hand, did not have any ready money, but seeing an
opportunity to make a safe investment, he borrowed ten thousand
dollars at six per cent interest for one year. He made the invest-
ment, "turned" the property within the year, and received
eleven thousand six hundred dollars. He returned the ten thousand
dollars which he borrowed, paid six hundred dollars interest, and
had one thousand dollars left as profit. It would be needless to
say that "B" made the more profitable investment-
Acre Profits. — As regards crop production, farmers and land
owners think in terms of acres, and they plan to secure the most
profits per acre. Ordinarily when they fertilize, they hope to
increase these profits even though the cost .of producing the crop
is augmented. Any fertilizer treatment, therefore, which gives
the greatest value of crop increases above the fertilizer and other
increased cost per acre will usually be the most profitable.

THE LAW OF THE MINIMUM 373

An Illustration. — On a certain soil two different fertilizers were
tried — the applications being made once in a three-year rotation.
The following are the three-year results concerning profits:

Fertilizers

Cost
per acre

Net value of increase
per acre per rotation

Per cent profit on cost
of fertilizer

A
B

$4.00
8.00

$15.00
21.60

375
270

It is to be noted that the fertilizer "A" gave a net return of
$15.00 per acre, or 375 per cent profit on the cost of fertilizer;
and "B" gave a net return of $21.60 per acre, which is 270 per
cent profit on the cost of the fertilizer. The fertilizer which gave
a net profit of 270 per cent returned $6.60 more per acre than
the fertilizer which gave a net return of 375 per cent on cost
of fertilizer.

Suppose a man had fifty acres of similar land and had only
$200 of ready money to expend for fertilizers. He would be a poor
business man, indeed, if he could not see that if he borrowed $200
one year to enable him to fertilize every acre with fertilizer "B,"
he could realize $330 more net profits, and in so doing realize at
least 165 per cent profit on the money borrowed.

When such conditions prevail as regards the use of fertilizers
the land owner must first determine whether or not the change in
method of crop production will reduce the number of acres he can
raise, since the goal in profitable farming is " greatest amount of
profits per man." If the method of fertilization does not reduce
the number of acres of crop he can raise under his system of farm-
ing, then both fertilizers (A and B) would be profitable — and the
one which gives the greater net profits (dollars) per acre is the
more profitable.

Proper Kind and Amount of Fertilizers. — Two important
factors come into play in determining the profitable use of com-
mercial fertilizers, namely, the proper kind of fertilizers and the
right amounts that should be used. These two factors may be
expressed in terms of two economic laws, as follows: The "lav
of the minimum" and the "law of diminishing returns."

The law of the minimum as related to fertilizers and crop pro-
duction may be stated as follows: // the soil is deficient in one
particular element of plant-food, the yield of a given crop will be
limited by the amount of that particular element contained in the

374

PROFITABLE CROP PRODUCTION

fertilizer added. For example, if a soil contains an abundant and
available supply of all the plant-food elements except phosphorus,
and all other factors and conditions are favorable, the yield, in a
large measure, will be proportional to the amount of available
phosphorus added in the fertilizer. No excess of the other elements
will make up for the shortage of phosphorus (Chap. VII, Fig. 33).

The law of diminishing returns as it is applied to fertilizers
may be stated as follows : The first expenditure of a proper or needed
fertilizer is usually the most effective. Each additional increase in
application produces smaller and smaller returns, until a further
increase causes no increase in the yield.

This is well illustrated by an experiment on wheat, begun in
1852, at Rothamsted, England, the oldest experiment station in
the world. Several adjoining plots received mineral fertilizers
such as phosphates and potash, in greater amounts than were
removed by the crops. In addition to the mineral fertilizers, a
nitrogen fertilizer was applied in different amounts. One plot
received no nitrogen fertilizer, another 200 pounds per acre, a
third 400 pounds, a fourth 600 pounds, and a fifth 800 pounds per
acre.4 The fertilizers were applied every year and each year
wheat was grown. At the end of the thirteenth year the following
average results were secured:

Diminishing Returns from Nitrogen

Treatments per Acre

Average Yield
for 13 years

Increase

Increase per
200 Ibs. Nitro-
gen Fertilizer

Mineral fertilizers but no nitrogen . .
Mineral fertilizers + 200 Ibs. nitrogen
fertilizer

Bu.

18.3

28.6

Bu.
10.3

Bu.

10.3

Mineral fertilizers -f 400 Ibs. nitrogen
fertilizer
Mineral fertilizers + 600 Ibs. nitrogen
fertilizer

37.1
39.0

18.8
20.7

8.5
1.9

Mineral fertilizers + 800 Ibs. nitrogen
fertilizer

39.5

21.2

0.5

The fourth column shows that the first 200-pound application
of the nitrogen fertilizer returned 10.3 bushels. Increasing the
application by 200 pounds caused an additional increase of 8.5

4 Equal parts of ammonium sulfate and ammonium chloride. The Book
of the Rothamsted Experiments, 1917, pages 34 and 46. The experiment
is still being continued.

SUMMARY 375

bushels. The third 200-pound increase returned 1.9 bushels, and
the fourth 200-pound increase of the nitrogen fertilizer returned
only one-half a bushel. These results clearly show that increasing
the application of a needed fertilizer does not necessarily mean a
corresponding increase in the yield. Doubling or trebling the
application does not necessarily mean doubling or trebling
the increase.

The relation between cost of production and profits may be
shown by the diagram in Figure 234, which indicates the profits in

per bushel

No fertilizer Properly fertilized Excessively fertilized

Fia. 234. — Diagram showing the relation between cost of production and profits.

corn production on poor land without fertilization, when properly
fertilized, and when excessively fertilized. It is to be noted that
when the market value of the crop is high, the profits per acre are
much greater than when prices are low. Ordinarily, the greatest
net profits per acre can be realized when the soil is properly fertil-
ized, and when high crop prices prevail.

Summary. — Successful farming is determined in a large measure
by maximum profits in crop production and not necessarily by
maximum yields. High yields may not always mean large profits.
Doubling the yield may not mean doubling the profits. The use
of fertilizers has a direct bearing upon the net profits to be secured
in growing crops. The value of the crop increase per acre above

376 PROFITABLE CROP PRODUCTION

cost of fertilizer and other increased costs should be the basis for
determining profits from fertilizers. When the use of fertilizer
does not reduce the number of acres operated per man, the profits
per acre above fertilizer and other increased cost per acre determine
profitable fertilizer practice. When two or more fertilizers are
found profitable on the same soil, the most profitable is the one
which gives the greatest amount of net profits per acre. The
greatest net profits per acre are obtained when the fertilizer needs
of the soil are properly met and high crop prices prevail.

Home projects in fertilizing should be started by students and farmers.
Common local crops should be grown with and without the fertilizers contain-
ing the elements which those crops remove from soils. A number of strips
may be grown on which the fertilizers differ in amount and kind. Keep
records of the cost and yield and determine the net profit per acre in each case.

QUESTIONS

1. Are large crop yields per acre the most profitable? Explain.

2. Discuss the relation of profitable crop production to successful farming.

3. What determines fertilizer practice? Discuss.

4. Why is it not necessary for soil fertility investigators to determine the

effect that soil improvement measures have upon managerial income?

5. What is meant by managerial income? Land rental?

6. What is a most important problem which confronts the farmer as regards

his farm profits? How may this be determined?

7. How should profits from fertilizers be determined? Discuss.

8. When two or more fertilizers are compared what should determine which

is the most profitable? Discuss.

9. What two factors come into play in determining the profitable use of

commercial fertilizers? These factors may be expressed in terms of
what two economic laws?

10. State the "law of the minimum" as it is applied to fertilizers. Illustrate.

11. State the "law of diminishing returns" as it is applied to fertil-

izers. Illustrate.

12. Summarize the important points discussed in this chapter.

CHAPTER XXIV

FARMING IN REGIONS OF LIMITED RAINFALL

Dry-Farming. — Dry-land farming, or dry-farming, is com-
monly understood to mean the profitable production of crops
without irrigation on lands receiving less than thirty and at least
fifteen inches of rainfall annually. In reality there is no such
thing as dry-farming. No crops can be produced on dry land. So-
called dry-farming has for its object the reclamation of vast areas
of unirrigable lands which were formerly thought to be of no agri-
cultural value. It is a striking fact that about sixty-three per cent
of the whole area of the United States receives less than thirty
inches of rainfall annually. Eighteen Western states are included
in this area. About twenty per cent of this area, or about 240,-
000,000 acres, receive less than fifteen inches. There are, therefore,
more than a billion acres that may be called dry-farming lands
in Western United States.

Information Has Been Meager. — In the past only meager
and unreliable information could be secured concerning dry-land
farming. Within recent years, however, experimental data have
been secured which will greatly aid in solving many of the problems
confronting the dry-land farmer.

It is to be understood that the climate in the dry-farming
region is not uniform, but variable. One season may have almost
humid, and another almost arid conditions. The distribution of
the rainfall, likewise, is variable. It is not an unusual occur-
rence to have a single torrential downpour of rain which exceeds
in the amount the normal rainfall for the month in which it
occurs. At other times a monthly precipitation of 1.9 inches
may come in nine light showers and prove of no practical value
because all the moisture evaporates before it can penetrate the
soil mulch.

The Water Problem. — The main problem thus far in growing
crops without irrigation in regions of limited rainfall concerns the
conservation of the rainfall for crop use (Chapter VIII). It has
been demonstrated that by proper methods there need be no com-
plete crop failure on suitable soils wherever the annual rainfall is

377

378 FARMING IN REGIONS OF LIMITED RAINFALL

above fifteen inches. In some sections twelve inches or less of
rainfall is sufficient for dry-farming. The amount of rainfall during
the growing season is a better criterion of crop production than the
annual rainfall.

Soils in Dry-Farming Regions. — Soils in dry and semi-arid
climates are rich, because of the comparatively small amount
of leaching during past ages. A great variety of soils exist —
ranging from heavy clay and alluvial loam to fine sand and
coarse gravel, and varying in depth from a few inches to many
feet. A dry-farm soil should be intermediate in texture, uniform
and deep, and should support a good growth of natural vegetation,
preferably sagebrush.

The success of dry-farming is determined in a large measure
by the deep, congenial subsoils so generally characteristic of arid
and semi-arid regions. This enables the roots of crops to pene-
trate deeply, thus enabling them to secure deep as well as
broad pasturage.

Farming Methods. — Many wrong ideas have prevailed con-
cerning dry-farming methods. Recent experiments, however,
seem to warrant the following statements:1

(a) No definite " system" of dry-farming has been or is likely
to be established that will apply generally to all or to any con-
siderable part of the dry-land area.

(6) No hard and fast rules can be adopted to govern the
methods of tillage or of the time and depth of plowing.

(c) Deep tilling does not necessarily increase the water-holding
capacity of the soil or facilitate root development.

(d) Alternate cropping and summer tillage can not be relied
upon as a safe basis for a permanent agriculture or to overcome
the effect of severe and long-continued droughts.

(e) The farmer can not be taught by given rules how to operate
a dry-land farm.

Crops for Dry-Farming. — In dry-land farming the selection
of proper crops and their proper seeding, care and harvesting are
as important as choosing a suitable soil and preparing it properly.
In general, crops cultivated in humid regions are also grown on
semi-arid lands. However, varieties especially adapted to dry-
farming conditions must be used. In some sections it is most
important to select those crops which will make most of their

1 United States Department of Agriculture Yearbook, 1911.

CROPS FOR DRY-FARMING 379

growth during the period of most rainfall, and those which will
make the most efficient use of the soil moisture. Some dry-farm
crops are here mentioned in the order of their importance.

Wheat is the leading crop — including winter and hard spring
varieties.2 This crop shows a closer relation between the yield
and the moisture content of the soil than any other crop. In the
northern portion of the dry-land area corn or other cultivated
ground makes the best preparation; in the central portion, early
fall plowing and cultivated ground is good; and in the south-
ern section winter wheat seeded late on small grain stubble is
most profitable. In the southern portion, land preparation
for winter wheat should begin immediately after the harvest of
small grains.3

Oats is a promising dry-land crop. Summer tillage has produced
higher yields than any of the other cultural methods, but the great-
est profits per acre have been realized when oats were sown on
disked corn land. Where listing has been tried, it proved more
profitable than fall plowing.

Barky grows fairly well on dry-farms, especially those varieties
belonging to the beardless and hull-less types. Largest yields
are produced on summer tilled land, but slightly more profits
per acre have been realized when the ground is prepared with a
lister instead of a plow.

Rye is one of the surest dry-land crops. The winter varieties
are usually most satisfactory.

Corn is a most excellent crop to grow for fodder and to prepare
the land for a crop of small grain. It has been found that no one
method of seed-bed preparation seems essential to the production
of this crop, especially in the Great Plains.

Sorghums promise to become excellent crops for dry-farming.

Alfalfa is a most valuable crop to grow in the valleys especially,
on account of the more favorable moisture conditions. Some-
times alfalfa is planted in rows to permit of intertillage, and to
lessen the draft on the moisture supply.

Peas have been found an excellent legume in some sections,
and may be substituted for summer fallowing.

2 The hard winter wheat, especially — Kharkow and Turkey Red of the
Crimean group. The varieties of common spring wheat usually grown are
the Blue Stem and Red Fife. Durum or macaroni wheat is also much grown.
Department of Agriculture Bulletin 268, and Farmers' Bulletin 895.
"IT. S. Farmers' Bulletin 895, 1917.

380 FARMING IN REGIONS OF LIMITED RAINFALL

DRY-FARMING PRACTICES

Cultural Methods. — On fourteen different Experiment Station
farms within the Great Plains area, experiments have been con-
ducted, some extending over eight years, in determining the com-
parative value of fall plowing, spring plowing, disking corn stubble,
subsoiling, green manuring and summer tillage4 in preparation
of the soil for wheat, oats, barley, corn, milo and kafir.5 Listing
was also tried.6

The following general conclusions were reached: (a) When
the climatic conditions are as favorable as those often experienced
in all parts of the Great Plains area on all the types of soil repre-
sented, profitable crops can be produced by any one of the several
different cultural methods such as are in common use; (6) when
the climatic conditions are unfavorable, no profitable crop of any
kind tested can be produced by any of the cultural methods
under investigation.

Plows and Depth of Plowing. — Disk plows are commonly
used. Evidence so far obtained goes to show that nothing is
gained by stirring the soil to a depth greater than is done by ordi-
nary plowing, eight inches or less in depth. Whether plowed or
not, it is important to leave the ground in a condition which
will retain the maximum quantity of snow during winter. Fall
plowing is usually best.

Depth, Rate and Time of Seeding. — Depth of seeding seems
to be of less importance than the proper time of seeding, which,
of course, varies in different sections. Results seem to show that
thin seeding is more favorable than when ordinary amounts of
seed are sown per acre in humid regions, though in some sections
where the rainfall is more favorable, ordinary rate of seeding is
better. The grain drill is better than the broadcast sower. On
the lighter soils the press-wheel drills give excellent results
(p. 156).

Moisture Conservation. — Difference in depth of plowing seems
to have no effect on moisture conservation. In some sections
it has been found necessary to leave the soil uncropped but culti-
vated during each alternate. year in order to save up enough mois-
ture for a crop. Cultivation is an important operation in dry-

4 Summer tillage means the tillage of an uncropped fallow field during an
entire season.

6 Milo and kafir are two varieties of kafir corn, one of the classes of sorghum.
6 U. S. Department of Agriculture Bulletin 268.

QUESTIONS 381

land farming to conserve moisture. Some investigators believe
that cultivation to establish and maintain a soil mulch is not so
important a factor in moisture conservation as cultivation to
kill weeds.

Use of Fertilizers. — Since the soils in dry-farming regions are
generally rich, especially in the mineral elements, commercial
fertilizers have not been used.

Crop Rotation. — In general, little has been done in determining
proper rotations for dry-farming. A rotation of oats, corn and
wheat has been tried with good success in some sections. For
further information, see page 277.

Stock in Dry-land Farming. — Early dry-land farming was
devoted almost exclusively to the production of crops, especially
wheat. No thought was given to the maintenance of fertility.
Even now little attention is being given to maintaining the pro-
ductiveness of the soils. Semi-arid soils are rich in the mineral
elements, but are deficient in organic matter. It seems advisable
to introduce stock to utilize roughage, and especially to aid in
establishing crop rotation and in maintaining fertility. Thus far
dairying seems the most profitable type of stock farming.

Good farming is as essential to successful dry-land farming as
it is elsewhere. Good farming means practicing the best methods
of producing the largest crops with the greatest net profits, and
leaving the soil in the best condition for the production of the
crops which follow.

Dry farming projects may be conducted not only in regions of limited
rainfall but also in regions where there is danger of summer drought. Such
projects may include the growing of dry region crops, the practice of deep
plowing, subsoiling, sub-surface packing, maintenance of dust mulch, use of
other mulches, etc.

QUESTIONS

1. What is meant by dry-farming? Is this kind of farming of much import-

ance? Why?

2. Discuss the uniformity of climate and distribution of rainfall in the
. dry-farming regions.

3. What is the important problem in dry-land farming? What is the mini-

mum amount of rainfall necessary?

4. Discuss the character of arid and semi-arid soils.

5. Discuss the importance of the character of the subsoil in dry-farming.

6. Have "iron-clad" farming methods been established for dry-land fanning?

Discuss this point.

7. Name some crops, that are especially well adapted to dry-farming.

382 FARMING IN REGIONS OF LIMITED RAINFALL

8. In general, what have been some of the results of experiments in deter-

mining the value of different cultural methods in dry-farming?

9. What is gained by deep plowing over shallow plowing?

10. Discuss the depth, rate and time of seeding in dry-farming.

11. What is the most important farm practice in moisture conservation? Why?

12. Is stock farming possible in dry-farming? Discuss its importance.

13. Is good farming essential to success in dry-land farming? What is meant

by good farming, generally?

14. What dry-farming methods have you seen used, even in humid regions?

APPENDIX

383

APPENDIX

Composition of Feeds

Average Dry Matter, Digestible Nutrients arid Fertilizing Constituents in Some

Common Feeds*

Amount in 100 Pounds

Feeds

Dry
matter

Digestible Nutrients

Fertilizing
Constituents

Crude
pro-
tein

Carbo-
hy-
drates

Fat

Nitro-
?N>

Phos-
phorus

(P)

Potas-
sium
(K)

Alfalfa hay .

91.4
90.7
92.5
87.7
89.4
88.2
87.1
91.4
87.8
89.5
87.8
88.7
26.3
90.6
92.1
88.4
90.3
91.1
91.3
90.9
89.9
9.4
13.6
9.9
87.5
87.2
90.8
88.5
90.9
21.2
90.5
90.6
90.1
91.4
16.4
92.5
88.4
89.8
89.9
89.6
89.9
7.5

10.6
9.0
21.5
7.9,
9.7
8.6
7.6
10.9
4.0
7.5
7.7
6.9
1.1
2.2
31.6
19.4
13.1
16.5
21.6
30.2
2.9
0.8
3.3
3.6
5.0
4.3
9.7
1.0
30.2
1.1
7.3
9.9
30.7
11.7
1.2
56.3
3.0
9.2
12.5
13.3
9.6
1.0

39.0
66.8
30.5
36.9
36.8
41.1
39.3
38.2
39.7
67.8
66.1
69.0
15.0
47.8
25.6
54.5
33.7
42.6
51.9
43.9
45.0
6.4
4.9
5.1
46.0
44.3
52.1
42.6
32.6
15.8
48.1
68.4
22.8
39.2
12.6

42 '.8
67.5
41.6
46.3
47.3
4.5

09
1.6
6.1
1.1
1.0
1.1
1.8
0.7
1.1
4.6
4.6
3.5
0.7
1.0
7.8
1.1
1.0
10.4
3.2
4.4
1.0
0.0
4.3
0.2
1.8
1.2
3.8
0.9
6.7
0.0
10.6
1.2
14.4
1.2
0.04
12.7
1.2
1.5
3.0
4.3
3.6
0.7

2.38
1.84
4.24
2.05
2.26
1.94
2.05
2.32
1.38
1.62
1.66
1.49
0.34
0.94
6.02
3.78
3.09
3.62
4.06
5.68
1.06
0.22
0.56
0.61
1.33
1.22
1.98
0.58
5.42
0.35
1.89
1.89
5.84
2.56
0.26
9.7
0.99
1.98
2.56
2.77
2.13
0.16

0.236
0.37
0.431
0.305
0.27
0.45
0.17
0.29
0.2
0.3
0.296
0.283
0.069
0.196
1.16
0.44
0.41
0.575
0.27
0.24
0.183
0.017
0.083
0.096
0.157
0.157
0.353
0.09
0.742
0.052

0.32
0.594
0.296
0.035
2.14
0.135
0.375
1.286
0.92
0.322
0.052

1.85
0.614
0.075
1.44
1.86
1.72
1.35
1.05
1.58
0.332
0.324
0.31
0.36
1.07
1.49
1.24
3.43
0.21
0.19
0.1
0.94
0.18
0.14
0.14
1.78
1.36
0.465
1.245
1.054
0.044

0'.473
2.05
1 93
0.265
0.72
1.13
0.44
1.344
0.98
0 63
0 215

Brewers' grains (dried)

Clover hay, crimson

Clover hay, sweet (white)

Clover and timothy hay (mixed)

Corn, flint

Corn silage (well matured)
Corn stover (ears removed, very dry) .

Cowpeas

Germ oil meal (high grade)

Gluten feed (high grade)

Johnson grass hay
Mangels . .

Milk, skim

Mixed grasses, hay

Oats . .

Oil meal (old process) >

Potatoes .

Rye
Soybeans .

Soybeans hay

Sugar beets (roots)
Tankage (high grade)

Timothy hay

Wheat .

Wheat middlings (shorts)

Wheat screenings
Whey

For other feeds consult Productive Feeding of Farm Animals, Woll.
* Compiled from Feeds and Feeding, Henry and Morrison, 15th Edition, 1915.

INDEX

Absorption of water by seeds, 49
favored by contact, 49
retarded by salts, 49
Acid phosphate fertilizer, 197, 199
absorption by soil, 213
acid character of, 224
application of, 199, 299, 312, 324
availability of, 197
choice of, 201, 202
mixed with other materials, 211
on acid soil, 202
vs. rock phosphate, 202
soils, extent of, 236
how to tell, 233
lime for, 231
on limestone, 242, 248
Acidity of soils. (See Soil acidity)
Acre profits from fertilizers, 372
Air, for soil medium, 13

source of carbon, 13
Agricultural lime, defined, 229

comparative value of, 244
kinds of, 238-244
laboratory exercises on, 252
source of, 154
testing value of, 232, 362
Alfalfa a heavy feeder, 65

amount elements removed by, 62
and crop rotation, 329, 339, 340
for sands, 316

good as a weed-killer, 78, 268
inoculation for, 230
lime for, 230-232
needs much potassium, 203
on acid soils, 231, 232, 249
rich in calcium (lime), 64
rich in protein, 64
root system of, 68
rotations for, 276, 277
when successful on acid soils, 249
where grown, 275
Alkali in soil, injurious, 258
soil, defined, 43, 44

deep rooted plants for, 259
drainage for, 259
management of, 260
spots, 44

remedy in drainage, 111
Alluvial soil, defined, 15

origin and value of, 17
Alsace, potash in, 202
Alsike clover, adaptation, 275

elements removed by, 62
response to liming, 233
Alumina, defined, 30, 31
Aluminum, defined, 30, 31
Ammonia gas, defined, 174

in horse stable, 224
Ammonium sulfate fertilizer, 196
Analyzing soils, 355-368

for lime needs, 358
for nitrogen needs, 359
for organic matter, 359
for phosphorus needs, 359
for potassium needs, 360
methods of, 358
Apatite, defined, 40

25

Aphids and yields, 256, 258

Apples, elements removed by, 69

Arid climate, defined, 44

soil, characteristics of, 44, 378

Availability of elements, defined, 54
affected by iron in soil, 262
of nitrogen fertilizers, 196
of phosphate fertilizers, 197
of potash fertilizers, 202
of, vs. total amount, 199, 356

Bacteria and crop failure, 181

are plants, 178

for soil medium, 13

in soil, 171-2

legume, 172, 180

nitrogen-gathering, 172, 175

number of in manure, 216
soil, 13, 171

size of, 171

Backfurrow, 113, 139, 148
Barley, elements removed by, 62

for sands, 317

response to liming, 233

rotations for, 275, 276, 280
Barnyard manure. (See Manure)

water, why colored, 224
Basic slag fertilizer, 197, 198

availability of, 197
choice of, 202
Basalt, defined, 39
Beans, where grown, 281
Bench terraces, defined, 289
Beet, sugar, elements removed by, 62

root system of, 68

(See under Sugar beets)
Black alkali, defined, 44
Blank test plots, 360
Blinding tile, defined, 1 19
Blood meal fertilizer, 196, 197

availability of, 196

in relation to decay, 173
Blue grass, elements removed by, 62

litmus paper, 229
Bog cutter, 297

"Bogus" spots in marsh soils, 302
Bone meal, fertilizer, 197, 198

availability of, 197

choice of, 201
Broadcast grain sower, 158
Brome grass for sands, 317
Buckwheat, elements removed by, 62

for green manuring, 66, 192, 194

for sands, 317

rotations for, 278
Burnt lime for peat, 245

for soils, 243
Business of the farmer, 37

Cabbage, a heavy feeder, 64
club root of, 233, 257, 259
elements removed by, 62, 68, 203
resistance to yellows, 258, 260
response to liming, 233
root system of, 68
yellows and fertility, 257, 260

Calcite, defined, 40

385

386

INDEX

Calcium, defined, 30, 31

amount removed by crops, 62, 63
amount removed by fruit, 69
and protein relations, 64
function of, in plants, ">">
how distributed in plants, 63
Capillary rise of water, 96

factors influencing, 96, 97
how aided, 102
laboratory exercises on, 105
water, denned, 93

importance of, 93
how held by soil, 93
Carbon, defined, 30, 32
dioxide, defined, 6
function of, in plants, 55
how plants secure, 35, 36
much used by plants, 36
Carbonate of lime, defined, 41
deposit of, 239
for liming, 238
laboratory exercises on, 251
origin of, 41
test for, 238
Carbohydrates, defined, 57

and potassium relations, 64
laboratory exercises on, 57
Catch crops, defined, 174

value and uses of, 193, 272
Chalk, natural, 243
Chemical analysis of soils, 30, 356
has limitations, 355
uses and value of, 257, 258
changes in soils, 6
composition, of animals, 36
plants, 36
soil, 29, 30
elements, defined, 29

how exist in soil, 30
formula, defined, 30
symbol, defined, 30
test for carbonates, 238
for soil acidity, 234
Chloride of potash, fertilizer, 202
Chlorophyll defined, 50
Cherries, elements removed by, 69
Classification of soils, 14
on basis of origin, 15
of texture, 14
of type, 22

Clay, defined, 11, 12, 14
advantages of, 321
clearing, 324
crops to grow, 325
drainage in, 322
erosion problem in, 324
field studies on, 326
home projects on, 326
loam, defined, 14

mechanical composition of, 14. 15, 321
lime, use of in, 323
nitrogen problem in, 323
organic matter problem in, 323
particles, defined, 11, 12
phosphates in, 324
plowing in, 325
plowing of, 15, 142, 325
rotations for, 325
soil class, 14
soil management, 321, 325
special problems in, 321
sweet clover for, 323
tilth (good) in, 322
types of farming, 325
true, 41

Climate, arid, defined, 44
effect of, on soil, 42
humid, defined, 42
relation to fertility, 80
semi-arid, defined, 44
sub-humid, defined, 42
Clod crushers, 154, 155
Clover, adaptation of, 275

elements removed by, 62
for green manuring, 191, 193
maintaining farming, 177, 191
marsh lands, 304
sand farming, 316
good, a weed-killer, 78, 268
sod better than timothy, 181
where grown, 275
Club root of cabbage, 233, 258, 259
Colluvial soil, defined, 15

origin and value of, 22
Commercial fertilizers. (See Fertilizers'*
Complete fertilizers, defined, 205

determining equivalent of, 198, 202
expressing equivalent of, 205
use of, 205, 206
Composition of feeds, 383
soil, 11, 29, 30
influences plant growth, 34
Conservation of soil moisture, 100-105
in sand farming, 313
laboratory exercises on, 105, 106
Continuous cropping defined, 264
Coral, as agricultural lime, 243
Corn, cultivation of, 162

elements removed by, 62
for sands, 316
home projects on, 169
on peat soils, 125, 187, 201, 204
production on decline, 1
response to fertilizers, 200, 201, 206-208
root development of, 53, 68
root-worm and fertility, 255
rotations for, 275-280
where grown, 279
Corrugated roller, 155
Cost of fertilizers, an expense, 372
Cotton, elements removed by, 62
for sand farming, 317
rotations for, 279, 280
where grown, 279
Cottonseed meal, fertilizer, 196, 197
availability of, 196
relation to decay, 173
Coulters, 141
Cover crops, 193, 272

for soil erosion, 288
Cowpeas, illustrated, 191

elements removed by, 62
for green manuring, 191, 192
Crimson clover, illustrated, 192
for green manuring, 191, 192
for sands, 316

Crop production, and fertilizer practice, 369
determines fertilizer use, 369"
relation between cost of, and

profits, 375
profitable, 369-376

the farmers' problem, 370
rotation, defined, 263

alfalfa in, 329, 331, 339, 340

application of principles, 332, 342

best for soil improvement, 274

benefits of, 264, 270

chart, 331

controls insects and diseases, 264

cropping problems solved by, 329

INDEX

387

Crop rotation, definite, defined, 263

in practice, 263, 275
economic yields resulting from, 272
factors determining kind of, 328

proper, 272
farm management in relation to,

327

fertilizers do not take place of, 271
fertilizing elements conserved by, 2
field studies on, 2S2, 342
fixed, defined, 263
for all farms, 341
for clay soils, 325
for cotton, 336
for cowpeas, 338
for depleted silt loams, 326
for dry-land farming, 277
for gardening, 280, 281
for general farming, 331, 342
for marsh soils, 304
for North Atlantic States, 277
for North Central States, 275
for Pacific States, 280
for sandy soils, 317
for South Atlantic States, 278
for South Central States, 279
for stock farming, 329
for truck farming, 280, 281
helps to maintain fertility, 268-270
home projects on, 282, 242
how to plan, 329

for grain farming, 330
for stock farming, 330
for truck farming, 331
illustrated, 332-342
increases organic matter, 265, 274
legumes in, for best results, 272
liming problems solved by, 276
not always beneficial, 271
on hillsides, 288
other points on, 339
practical, 328

problems, in illustrated, 332-342
remedy for diseased soil, 257
short better than long, 274
soil fertility in relation to, 263
soil problems solved by, 329
some systems of, 274
special, for alfalfa, 340
summary on practical, 341
systematizes farming, 328, 341
tilth improved by, 266
to meet several soil problems, 338,

341

weeds controlled by, 268
wheat yields increased by, 271
Crops, advantages in growing different, 327

and soil determine fertilizer needs, 208

as feeders, 61-63

because of decay, 172

benefited by liming, 232, 233

change of, not always beneficial, 271

demanding much potassium, 203

factors in growing, 75

failure of, and bacteria, 181

failure of, due to diseases, 257

fertility indicators, 80

for heavy clay soils, 325

for marsh lands, 305

for sands, 316

grow, in right combinations, 272
order, 273

grown, in dry-land farming, 277
in North Atlantic States, 277
in North Central States, 275

Crops grown in Pacific States, 280

in South Atlantic States, 278
in South Central States, 279
growth of, and light, 77, 78

and weeds, 7x

increased by rotation, 268-271
injured by liming, 233
large, may not be most profitable, 369
plowing under, for green manure, 193
plow under or feed, 195
remove mineral elements, 33, 62, 63
secret in growing, 86, 87
secure elements from two sources, 172
tolerating soil acidity, 233
vary in their requirements, 64
yields of, affected by temperature, 51
in England, 2
in France, 2
in Germany, 2
in United States, 2
relatively low, 2
Cultivation, defined, 161

favors nitrification, 161, 174, 357
level vs. hilling, 167
objects of, 161
right time for, 164
shallow is best, 167
to conserve moisture, 162
Cultivators, 161, 166
Culti packer, 155

Culture solution, how to make, 58
Cumulose soil, defined, 15

origin and extent of, 16
Cylinder fertilizer tests, 360

Diary farms, use of manure on, 221

of fertilizers on, 222, 345, 353
Deadfurrow, defined, 113
Decay, and crops, 172

of rocks, 1-9

of soil, 9

organisms of, lacking, 175
Deep tilling, 147
Depleted soils, defined, 84

improvement of, 326
Disk drills, 157

harrows, 151
Disking, the seed bed, 151

before plowing, 153

for summer fallowing, 153

potato land for grain, 153

to conserve moisture, 153

vs. plowing, 159
Disintegration of rocks, 1-9
Dolomite, defined, 40
Drag (harrow), 152
Drainage, defined, 109

and percolation, 95

benefits of, 109-112

by means of pumps, 126

erosion prevention, 287

factor considered in fertility, 355

field studies on, 133

how accomplished, 112

in clay soil farming, 321

laboratory exercises on, 132, 133

lands needing, 112

of alkali soils, 131, 258

of marsh lands, 294

noted projects, 126

sub-surface, 113, 115, 117

surface, 112, 114

vertical, 113

tile, 117-126. (See under Tile drainage)

what determines method of, 113

388

INDEX

Dried blood fertilizer, 196, 197

Drill application of fertilizers, 201, 206-208

Droughty soil, 99

Dry-climate soil, 377

Dry-land farming, denned, 377

crops for, 277, 378

crop rotations for, 277, 381

cultural methods in, 380

dairying in, 381

extent of dry-farm lands, 377

farming methods in, 378

fertilizers for, 381

good farming in, 381

listing for, 159

moisture conservation in, 380

planting and seeding in, 380

plowing in, 380

plows for, 380

projects (student) in, 381

rainfall in, 377

seeding and planting in, 380

soils best for, 378

stock raising in, 381

water problem in, 92, 377

water requirement in, 91
Dune sand, 309
"Dust" of the earth, 36
Dynamiting soils, 148

Earth, formative period of, 5
Elements, denned, 29

amount removed by crops, 61-63

conserved by rotation, 267

contained in subsoil, 72

distribution of, in crops, 63

exchange of, in farming, 350

forms in which plants secure, 61

function of, in plants, 55

how exist in soil, 30

how plants secure, 36, 54

laboratory exercises on, 58

made available by liming, 230

minerals,1 denned, 33

pass through cycles, 37

plant-food, denned, 54

removed by fruit, 69

required by plants, 35

source of, for plants, 35

supply of, in soil, 33

why some soils rfre deficient in, 40
(See under Plant-food elements)
Erosion. (See Soil erosion)
Experiment Station fertilizer tests, 362
Experimental fertilizer plots, 360-368
Exportation on decline, 1

Fall plowing, 144

retarded nitrification, 357
Farm crops consumed in U. S., 1
Farm management, 327

and crop rotations, 327-338
crop rotation chart aids in, 331
drainage relations, 112
soil problems common in, 327
successful, 327

systematized by rotation, 328, 341
Farmer's business, 37
Farmers conduct fertilizer tests, 362
Farm soil examination, 368

survey, 368
Farming, account with plant-food elements

in, 347-353
clay lands, 325
for profit, 369-376
grain, and soil depletion, 344

Farming, grain, revised, 344

and stock, combined, 347
vs. stock, 343, 346
in irrigated sections, 131
in regions of little rainfall, 377
in relation to soil fertility, 343
marsh lands, 293-307
N and P balance in, 347-353
sandy soils, 309-319

types of, 318
stock, and fertility, 345
is popular, 345
vs. grain, 343, 346
systems of, 343
trials in Illinois, 347
in Ohio, 345,346
Feeding of crops, 61, 63
power of plants, 66
stock, elements lost in, 350, 351
Feeds, fertilizing constituents in, 383

nutrient composition of, 383
Feldspar, defined, 40
Fertile soil, defined, 75

factors determining, 75
Fertility. (See Soil fertility)
Fertilization, defined, 190
and liming, 231
by alluvial deposits, 18
Fertilizer, attachments, 212
cost of, an expense, 372
practice and profits, 369

law of diminishing returns in, 374

of the minimum in, 373
tests, 67, 204, 223, 360-368

how experiment stations conduct,

363

how farmers can conduct, 362
in general, 360-373
on marsh soils, 200, 201, 204, 298,

300, 303

points to observe, 366
value of untreated plot, 370
Fertilizers, 196-213

absorption of, by soil, 213

amount to apply, 211, 299, 312-313, 324

broadcast vs. hill application, 213

chemical analysis to tell need of, 355

classes of, 196

commercial, defined, 196

computing profits from, 372

cost of, 207

determined by soil and crop, 208

determining profits from, 371

diagnosing soils for need of, 355

drill and hill application of, 211-213

economic laws in relation to, 373

effect of lime on, 230

efficiency of, increased by green

manure, 209
liming, 230, 231
moisture in soil, 205
organic matter, 173
fertility and fertilizer relations, 206
for marsh soils, 297-300
for peat soils, 297, 303
for sands, 311-313
green manuring helps, 209
high grade vs. low grade, 210
hill and drill application of, 211-213
home mixing of, 210

projects on, 225, 376
how elements in, expressed 196
to apply, 211-313
to determine need of, 355-368
indirect, 196

INDEX

389

Fertilizers, in general, 205

in maintaining fertility, 206
laboratory exe* rises on, 223, 224
lasting effects of, 213
low grade vs. high, 210
most profitable, 371
need of, determined by chemical analy-
sis of soil, 355-358
examining soil conditions, 355,

356
fertilizer tests in field, 67, 364-

368

pot tests, 204, 298, 360
soil and crop needs, 2O4, 208
pot tests for, 204, 298, 360
how to make, 223
profits determine use of, 207, 369

from, how to compute, 372
rules for use of, 210
soil and crop determine need of, 208
testing in the field, 360-368

importance of, 67, 68
in pots, 204, 298, 360
how to do, 223
not fully reliable, 204, 360
units, defined, 207
use of, determined by profits, 207, 369

by economic laws, 373
valueless without decay, 173
when fail, 205

most profitable, 371, 375
Fertilizing elements, defined, 33

account with, in farming, 347-353
balance sheet of, for a grain rota-
tion, 348

on dairy farms, 348, 353
conserved by crop rotation, 267
exchange of, in farming, 350-353
gained from purchased feeds, 350-

362

in feeds, 383
lose and gain of, in farming, 349,

350
lost by soil erosion, 283

in feeding transaction, 349, 350
regained in manure, 350
Field tests, 67, 188, 189, 200, 201, 204, 206-

208, 303, 360

Fine sandy loam, defined, 14
Fire-fanging of manure, 218
Flax, elements removed by, 62

crop rotation for, 276
Floating bogs, 16
Flooding (irrigation), 129
Food manufactured in plants, 37, 50
production per acre, 343

as grain vs. as meat, 343
Frost, effect of, on rocks, 6

on marsh lands, 302-303
Fruit, elements removed by, 69
Fruition period, 56
Furrow irrigation, 130

Garden crops and liming, 233
Gases as weathering agents, 6
Germination (period), 47

contact with soil, a factor, 49

critical, 47

fertilizers affecting, 49

laboratory exercises on, 56

moisture in relation to, 49

requirements and conditions for, 48

salts in relation to, 49

temperature in relation to, 49

water in relation to, 49

Glacial soil, defined, 15

origin of, 18

quality of, 21
Glaciers, effects of, 19-21

story of the, 18
Good farming, 381
Grade lath, use of, 118

line, illustrated, 119
Gradient, defined, 117
Grain drills, 156-158

for sand farming, 315
farming, defined, 343

for densely populated countries,
343

has led to soil depletion, 344

importance of, 343

maintaining fertility in, 347

revised, 344

stock and, compared, 346
on potato land, 153
Grains, lodging of, 64
Granite, defined, 39

soil from, 42
Grass on clay soils, 325

on sands, 316
Green manuring, defined, 190

an old practice, 191

benefits of, 190, 191, 194

best time for, 193

crops for, 192

cover crops for, 190

cultivation important in, 194

feeding the crop vs., 195

fertilizer relations, 209

for clay soils, 324

for cultivated crops, 194

for depleted silt loams, 326

for sands, 310

for soil improvement, 194

hints on, 195

in relation to liming, 231

importance of, in South, 193

legumes best for, 190

plowing under the crop, 193

precautions in, 193

to maintain organic matter, 191

Varro on, 191, 192

vs. fertilizers, 191

weeds for, 194
Greensand, 243
Gridiron system of tiling, 122
Ground bone fertilizer, 197, 198

water table, defined, 113
Growing period of plants, 49

activities in, 50

conditions and requirements in,

50,51

Gully erosion, defined, 286
Gypsum, defined, 40
for alkali soils, 259
for conserving manure, 218
for liming, 244

Hardpan, defined, 124

Harmful agents in soil, 255-262, 356

Harrows, 151-154

Harrowing, 151

Heat and cold, effects of, 6

Heavy soil, defined, 14

Hematite, defined, 40

Hemp, elements removed by, 62

response to liming, 233

soil for, 68

Herringbone system of tiling, 122
Hoe drill, 158

390

INDEX

Home mixing of fertilizer, 210

materials not to mix, 211
mixing rules, 210

Hornblende, defined, 40

Humid climate, denned, 4

Humus, denned, 12

Hydrated lime, 238, 244

Hydrogen, defined, 30, 33

Ice, a weathering agent, 6

the Ice Age, 18
Igneous rocks, defined, 39
Illinois grain vs. stock farming test, 346, 347
Infertility, defined, 80

causes of, 85

diagnosing, 86

toxin theory of, 261
Inoculation, defined, 182

a fertility factor, 182, 356

fails on acid soil, 232

field studies on, 185

for better crops, 182

home projects on, 185

how often, 184

laboratory exercises on, 185

methods of, 182

when succeeds on acid soil, 184, 232
Intertillage, 135, 161, 163
Iron, defined, 30, 31

function of, in plants, 56

rust, defined, 30, 31
Irrigation, affected by soil erosion, 284

an art of antiquity, 132

defined, 126

farming under, 131

how water is applied, 128
secured, 128

methods of, 129, 130

much land needs, 131

objects of, 127

profits in irrigation farming, 131

Jointers, 141

adjustments of, 141

Kafir corn, rotation for, 277, 280

where grown, 277
Kainit, fertilizer, 202, 203

Labor income, defined, 370

Laboratory instructions, 4

Lacustrine soil, defined, 15

origin and value of, 21

Land clearing, on marsh, 295
on steep slopes, 285
drainage. (See Drainage)
rental, defined, 370

Land-plaster. (See Gypsum)

Landslides, defined, 286

Lateral (tile), defined, 121

Law of diminishing returns, 374
the minimum, 373

Leaching of manure, 350

of nitrogen from soil, 349

Legumes, compared with non-legumes, 178
for dry-land farming, 277
for green manuring, 191-193
for North Atlantic States, 278
for North Central States, 275
for Pacific States, 280
for South Atlantic States, 278
for South Central States, 279
how they improve soils, 180
nitrogen gathered by, 178, 180
nodules on, 176-183
to solve nitrogen problem, 197

Light and crop growth, 77, 78
"Light" soil, defined, 15
Limate, defined, 244
Lime, agricultural, defined, 229
amount to apply, 245
as toxin destroyer, 261
carbonate of, defined, 41
carbonates, forms of, 238
comparative value of, 244
conserved by cropping, 247
defined, 30, 34
for clay soils, 243, 245, 323
for improving tilth, 323
for marsh soils, 245, 291
for pastures, 247
for quick results, 245
for root zone, 248
for sandy soils, 245, 312
from beet sugar factories, 243, 250
how it acts in soil, 229

to apply, 245

often to apply, 247

to determine good, 245
hydrated lime, 238, 244
kinds of agricultural, 238
laboratory exercises on, 252
lump or burnt, 243
misuse of, 249
mixing with manure, 219

fertilizers, 211
soil toxins relations, 262
spreader, 246
testing soil for need of, 232, 358, 362,

364

too much may prove harmful, 262
use and misuse of, 249
waste, 243

Liming, alfalfa response to, 232, 233
beneficial in green manuring, 231
benefits of, 229
best material for, 244
better than manure, 231
clay soils, 243, 245, 323
club root in relation to, 233
crops benefited by, 232, 233

injured by, 233

deep plowing no substitute for, 248
defined, 229

fertility regulated by, 250
for all crops 233
for quick results, 245
• for tilth improvement, 323
frequency of, 247
home projects on, 253
improves acid soils, 229
labor saved through, 231
land-plaster for, 244
marsh soils, 245, 301
only one of fertility factors, 250
pastures, 247
peas respond to, 233
peat soils, 245, 301
poor soils, 245

potato scab in relation to, 233
problems solved by rotation, 267
relation to soil toxins, 262
remedy for club root, 233
restoring worn-out soils, 250
sandy soils, 245, 312
to reduce total acidity, 249
when most profitable, 231
Limestone, acid soil possible on, 242
coarse, is slow acting, 240
defined, 39
dolomitic, 238

INDEX

391

Limestone, formation of, 43

home grinding of, 240, 241

how soils form from 42, 43

laboratory exercises on, 251

pulverized, 238

pulverizers, 240, 241

quarry, 239

Limoid, meaning of, 244
Line of tile defined, 117
Liquid manure, 215
Lister, 159

cultivator, 164
Listing, defined, 159, 160
Litmus paper, defined, 229

laboratory exercises on, 251, 252
test for acidity, 234
Loam, defined, 14

rotations for, 276
Loess soil, defined, 15

origin and value of, 32
Lodging of grain, 64
Lump lime, defined, 243

Magnesia, defined, 30, 31
Magnesium, function of, in plants 56

defined, 30, 31
Main (tile), defined, 121
Maintaining fertility, 206, 271
Mammoth clover for sands, 316
Managerial income, defined, 370
Manure (barnyard), a quick fertilizer, 216

affected by age of animal, 215
by bedding, 215
by feeding, 214

amount produced by stock, 215

application to clover fields, 220

as a fertilizer, 213

availability of, 216

bacteria in, 216

"burning" of, 218

care of, 216-218

compost heap, 218

cow, 214

defined, 213

demonstrations on, 223, 224

differ in fertilizing value, 214

facts about, 213

fire-fanging of, 218

for gardening, 218

for marsh soils, 200, 300

for maintaining fertility, 222

for sands, 310

for soil improvement, 216, 250

gypsum for conserving, 218

hen, 214, 218 j

hog, 214

horse, 214

land-plaster for conserving, 218

lasting effects of, 221

leaching of, 216, 222, 350

light vs. heavy applications, 219

lime in manure heaps, 219

liquid, valuable, 215

loss of ammonia from, 223

mixing horse and cow, 219

phosphate with, 220, 221

not a perfect fertilizer, 221

open yard vs. stall, 216, 222

pig, 214

pits for, 217

plowing under vs. disking in, 219

poultry, 214, 218

prod action of, by stock, 215

reinforcing, 220-222

residual effects of, 221

Manure (barnyard), rock phosphate for, 220-

sheds for, 217
sheep, 214

solubility of elements in, 210
stall vs. open yard, 216, 222
storing, 217
three-fold value of, 216
top-dressing with, 220
value of, 213, 214

vs. mineral fertilizers on marsh, 220, 300
winter applications of, 221
yard vs. stall, 216, 222
Mapping of soils, 22
Marble, defined, 39

dust for liming, 243
Marine soils, defined, 15

origin and value of, 21
Marl, defined, 243
for liming, 243
origin of, 17, 243
Marsh, defined, 14
soils, 16, 293

advantages in farming, 293
"bogus" spots in, 302
clearing and breaking, 295
clover for, 304
crop for, 302, 305
crop rotation, 304
drainage of, 117, 294
extensive farming on, 306, 307
fertilizer tests on, 200, 201, 204,

298, 300, 303

fertilizers for, 199, 203, 297-300
field studies on, 307
frost on, 302, 303
home projects on, 307
kinds of, 293
management of, 293
manure for, 300
most desirable, 294
types of, 293

of farming on, 306
Marsh-border soils, 293

drainage of, 294
Maximum production, 83
Meadow, defined, 25
Mechanical composition of soil, 14, 15
Medium red clover, elements removed by, 62

for sands, 316

Metamorphic rocks, defined, 39
Mica, defined, 40
Micro-organisms, 171
Middle-breaker, 160
Mineral elements, defined, 30, 33

removed by crops, 33
fertilizers on marsh, 200
matter, defined, 5
rock-forming, 40

laboratory exercises on, 45
soils, defined, 41
Mixed fertilizers, defined, 205

advantages in using, 209
application of, 209
determining equivalents, 198, 202
expressing equivalents, 198, 202, 205
for sands, 313
home mixing of, 210, 211
use of, 205-208
vs. single, 209
Moisture, and germination, 49

conservation and control, 100
laboratory exercises on, 105
supply on sands, 313
Molds, soil organisms, 171

392

INDEX

Muck soil, as soil type, 25

advantages in farming, 293

characteristics of, 293

denned, 16, 25

fertilizers for, 199, 203, 297-300

least desirable, 294

most desirable, 294

origin of, 16, 17

problems in cropping, 294

value of, 16

why better than peat, 41
Mulches, 104. (See Soil mulch)
Muriate of potash, fertilizer, 202

Natural systems of tiling, 120. 121
Nitrate fertilizers. (See Nitrogen fertilizers)

of soda, 197

Nitrates, denned, 174, 175
Nitrification, explained, 173, 175
destroys organic matter, 175
favored by cultivation, 357
laboratory exercises on, 185
retarded by fall plowing, 357
Nitrifying bacteria, 174, 175

lacking in some soils, 175
Nitrogen, defined, 30, 31

amount removed by crops, 62, 63

by fruit, 69

an account with, in farming, 347
analyzing soils for, 359
balance sheet in farming, 347-353
contained in feeds, 383
fertilizers, 196
function of, in plants, 55
gain in farming, 351-353
how held in soils, 33

much fixed by bacteria, 178
plants secure, 35, 36
in relation to fertility, 187
losses by soil leaching, 351

from manure, 216, 350
problem in sand farming, 310

solved by legumes, 197
supply of, in soils, 70, 71
Nitrogen fertilizers, 196 ;

availability of, 196
for sands, 310
leached from soil, 196, 213
needs increased, 209
fixation, defined, 178

amount of nitrogen fixed, 178, 180
by molds, 178
by soil bacteria, 175-180
by use of electricity, 178
how accomplished, 179

Nitrogen-phosphorus balance sheet, 347-353
illustrated, 352-353
in grain farming, 348
on a dairy farm, 348
Nodule bacteria, 172, 175, 180
are plants, 178
conditions favoring, 184
different kinds of, 182
discovery of, 176
how they work, 179
in relation to crop failure, 181
same for different legumes, 182
Nodules, defined, 179
alfalfa, 178
crimson clover, 177
garden pea, 183
inside of lupine, 179
medium red clover, 177
soybean, 176
Nutrient solution for plants, 58

Oats, elements removed by, 62
for green manure, 192
for sand farming, 317
response to phosphates, 189
rotations for, 275, 276
vs. barley to grow, 66
where grown, 276
Ohio grain-farming trial, 345
grain vs. stock farming, 346
test plots in field, 361-363
One-crop system, defined, 264

danger in, 264
Onions, elements removed by, 62

root system of, 68
Organic matter, defined, 6

aids decay of soil, 173
chemical composition of, 30, 175
decomposition of, 175
destroyed by nitrification, 175
fertility relations, 356
improves tilth, 266, 323
increases water-holding capacity,

98, 102
increased by rotation, 265

by fertilization, 266
in sand farming, 310
laboratory exercises on, 223
lessens soil erosion, 287
maintained by green manures, 191
maintains farming system, 191
makes fertilizers more effective, 173
rapid reduction of, 266
rotations to increase, 274
Organisms in soil, 13, 171
causing decay, 171, 172
in relation to fertility, 171
Osmosis, defined, 54
Outlet ditch, defined, 115

of tile drains, 122, 123
Oxygen, defined, 6, 30
and germination, 48
laboratory exercises on, 58

Parallel system in tiling, 122
Pasture on sands, 317
Pasturing and soil erosion, 286

loss of elements in, 351
Peaches, elements removed by, 69
Peanuts, response to liming, 233

rotations for, 279
Pears, elements removed by, 69
Peas, elements removed by, 62, 63
injury from blight, 257
response to liming, 233
rotations for, 276, 278, 280
Peat soil, advantages in cropping, 293

as soil type, 25

bogs on, 297

burning of, 295

characteristics of, 293

'cabbage on, 204, 305

clover for, 304

corn on, 187, 201, 236, 296, 298,
303, 305

crop rotation on, 304

crops for, 303, 305

deficient in mineral elements, 72

defined, 16, 25

drainage for, 294

extensive farming on, 306, 307

fertilizers for, 187, 201, 297-300, 303

firm seed bed important, 302

for blueberries, 234

for cranberries, 234

for sand improvement, 315

INDEX

Peat soil, grain on peat, 300, 305
home projects on, 308
how wrongly advertised, 72
least desirable, 294
lime for, 245, 301
manure for, 300
mild alkali on, 236
most desirable, 294
nitrogen fertilizer for, 299

problem on, 301
origin of, 16, 17
phosphates for, 299, 300
plowing, 295, 2€6
potash fertilizer for, 204, 299
problems in farming, 294
rape for, 306
rock phosphate on, 200, 201, 299,

300

roller for, 155, 302
seed-bed preparation, 297, 302
types of farming on, 306, 307
value of, 16, 294, 307
when acid, 236

non-acid, 236

why deficient in K and P, 40
wood ashes for, 301
Percolation, defined, 94

aided by roots and worms, 95
importance of, 95
Phosphate fertilizers, 197
acid vs. rock, 202
availability of, 197
choice of, 201
cost of, 207

determining equivalents, 198
expressing equivalents, 198
fertility relations, 222
for acid soils, 202
for clay soils, 324'
for marsh soils 201, 299
for reinforcing manure, 221, 222
for sandy soils, 312
for soil improvement, 326
home projects on, 253
results from, 188, 189, 199-201
rock vs. acid phosphate, 202
soils needing, 199
testing value of, 189, 364, 365
rock. (See Rock phosphate)
"Phosphoric acid," defined, 30, 34
Phosphorus, defined, 30, 32

amount removed by crops, 62, 63

by fruit, 69

analysis, value of, 359
available rather than total, 199
contained in feeds, 383
distribution of, in plants, 63
fertility relations, 85, 187
function of, in plants, 55
lost in growing tobacco, 267
purchased in feeds, 199
supply of, in soils, 70, 72
Phosphorus-nitrogen balance sheet, 347
illustrated, 352, 353
in grain farming, 348
on a dairy farm, 348
Planker, 154
Plant, a factory, 50

growth of, affected by soil, 34, 51

by temperature, 51
in nutrient solutions, 58
laboratory exercises on, 59
relation to soil and air, 34, 36

to animals, 36
Plants, conditions for growth of, 47

Plants, feeding power of, 66
great work of, 37
growth of in darkness, 59
subjects for study, 67
Plant-food elements, defined, 54

account with in farming, 347-353

amount regained in manure, 350

available vs. total, 356

crops feed on, 61

exchange of, in farming, 350-353

gain and loss of, in farming, 349

gain of, how determined, 351-353

gained from purchased feeds, 350-
352

in soils, 71

in subsoils, 72

laboratory exercises on, 58

loss and gain of, illustrated, 349, 350

losses of, how determined, 351-353

lost by pasturing, 351
by soil erosion, 283

leaching, 349

in feeding transaction, 349, 350
materials supplying, 190
total vs. available amount, 356
Planting and seeding, 156
Plow, 138-150

best time to, 144
disk, 142

equipment for the, 138
gang, 149, 150
general purpose, 141
hillside, 147
its work, 138-140
left-hand, 148
parts of a, 140
prairie breaker, 144
right-hand, 148
sod, 141
stubble, 141
subsoil, 145
walking, 140, 141
Plowing, 138-150

chain for turning weeds, 194
clay soils, 325
fall, 144, 146
hillside, 147, 149
moderately deep best, 146
no substitute for liming, 248
retarded nitrification, 357
sands, 315
sod, 140, 143
spring, 146
stubble land, 138
tractor, 149, 150
vs. disking, 159
when green manuring, 193
with subsoil plow, 145
Plow sole, defined, 147
Pot tests for soil needs, 204, 223, 298, 360

not fully reliable, 204, 360
Potash, defined, 30, 34

true meaning of, 34
Potash fertilizers, 202

absorbed by soils, 213

availability of, 202

cost of, 207

determining equivalents, 202

expressing equivalents, 202

for clay soils, 324

for marsh lands, 203, 204, 297

for peat soils, 203, 208, 297

for sands, 312, 313

soils needing, 360

source? of, 202

394

INDEX

Potash fertilizers, uses of, 203, 204
Potassium, amount removed by crops, 62.
63,69

carbohydrate relations, 64

chloride, fertilizer, 202

denned, 30, 32

distribution of, in plants, 63

fertility relations, 187, 360

fertilizers. (See Potash)

function of, in plants, 55

in feeds, 383

protein relations, 64

sulfate, 202

supply in soils, 70, 71

in subsoils, 72
Potato, cultivation for, 168

elements removed by, 63

for clay soils, 325

for marsh lands, 305

for eandy soils, 316

high yield of, 82, 87

response to fertilizers, 188

rotations for, 276

scab, disease, 265
lime and, 233
rotation a remedy, 265
Press drills, 156, 314
Profitable crop production, 369-375

acre profits, 371

fertilizer, determining, 371

liming, 231, 232
Profits and fertilizers, 207

basis on which to compute, 372 :

determining from fertilizers, 371

per acre, 371

relation of, to cost of production, 375
Protein and nitrogen in crops, 63
Pulverized limestone, 238
Pulverizers, 152-155
Pyrite, defined, 40 /

Quartz, defined, 40
Quartzite, defined, 39
Quicklime for liming, 243

Rainfall, at right time, 91
amount evaporated, 91

lost, 100

used by crops, 100
map of the United States, 101
Rape for green manure, 192
Raspberries, elements removed by, 69
Residual soil, defined, 15

origin and extent, 16
Rice, rotation for, 280
Rich soil, defined, 66
Ridge terraces, defined, 288, 289
River bottom erosion, 287
Rocks, affecting soils, 39
classes of, 39
defined, 40
field studies on, 46
laboratory exercises on, 46
Rock phosphate, fertilizer, 197, 198

availability of, 197

choice of, 201, 202

deposits of, 198

for black, prairie soils, 201, 202

for clay soils, 324

for depleted silt loams, 326

for marsh soils, 200, 300

for reinforcing manure, 220, 222

for sands, 313

how to use, 198

in relation to decay, 173

Rock phosphate, results with manure, 220,

vs. acid phosphate, 202

weathering, defined, 6-9

products of, 41
Rock-forming minerals, 40

laboratory exercises on, 45
Roller and tilth, 54, 154-156
for marsh soils, 302
for sandy soils, 313
Rollers, 154, 155
Roosevelt Dam, 129
Root, growth and drainage, 110

hairs, 68, 69

of corn plant, 53

maggots, 256

systems of plants, 68
Root-knot, 257
Rotation. (See Crop rotation)

chart, 331

Rothamsted Experiment Station, 374
Rowen, defined, 195
Rye, elements removed by, 63

for green manure, 192

lor marsh soils, 305

for sands, 316

rotations for, 276

Salt of the sea, 43

Salts, and germination, 49

in soil medium, 13

products of nitrification, 175

of rock weathering, 41
Sand grains, defined, 12

soil, defined, 14
Sands, advantages in cropping, 309

blowing of, 314

crop rotations for, 317

crops for, 315

dune, 309

fertilizers for, 310-313

field studies on, 320

grain drills for, 315

green manuring for, 194, 310

home projects on, 320

improvement of, 311

kinds of, 14, 309

lime for, 240, 245, 312

liming, 312

management of, 309-320

manure for, 310

mixed fertilizers for, 313

moisture supply in, 313

nitrogen fertilizer for, 311

organic matter important in, 310

pasture on, 317

peat for improving, 315

phosphates for, 312

plowing, 315

potash for, 312

problems in cropping, 310
• rock phosphate for, 313

rotation improves, 266

rotations for, 276

seed-bed preparation, 313

soybeans for, 312, 316

stock farming on, 329

subsoiling, 313

sugar beets for, 317

tiling, 120

types of soils, 309

of farming on, 318

vegetation indicates value of, 309

velvet bean for, 310

water-holding power of, 98, 313

INDEX

395

Sands, weight of, 15, 71
Sandstone, defined, 39

soil derived from, 42
Sandy loam, defined, 14
rotation for, 276
Sandy soils, defined, 14
kinds of, 309
(See under Sands)
Schist, denned, 39
Sedentary soils, 15
Sedimentary rocks, 39
Sediments, amount in streams, 17
carried into Gulf of Mexico, 18
soils from, 17
source of, 17

Seed bed, 48, 49, 135, 156
good, defined, 54

favors planting, 156
for peat soils. 302
for sandy soils, 313
preparation of, 48, 138
Seeders, 157, 158
Seeding and planting, 156
Seeds, absorption by, 49

contact with soil, 49, 156
fate of, when planted, 47
laboratory exercises on, 47
relation to seed bed, 51, 156
what constitutes good, 76, 77
Seepage, defined, 95
Semi-arid climate, 49

soils, 378
Shale, defined, 39
formation of, 43
soil derived from, 42
Shavings for bedding, 351
Sheet erosion, defined, 286
Shells, for liming, 243
form limestone, 43
origin of, 43
Shoe drills, 158
Silica, defined, 30, 31
Silicon, defined 31
Silt, defined, 12

loam, defined, 146
Skinner svstem of irrigation, 130
Slate, defined, 39

soil' derived from, 42
Smoothing harrow, 152
Sod plowing, 140, 142, 143
Sod plows, 141, 144
Sodium, defined, 30, 32

nitrate fertilizer, 196
Soil, defined, 5

acidity, defined, 45, 229

alfalfa and clover indicating, 234
blueberries indicate, 234
cause of, 237
chemical tests for, 234
cranberry indicating, 234
crops injured by, 233
crops tolerating, 233
demonstrations on, 251
fertility relations, 229
field studies on, 253
gypsum for, 244
harmful effects of, 229
horsetail rush indicates, 236
how determined, 233
laboratory exercises on, 253
land-plaster for, 244
lime to correct, 229
litmus paper test for, 234
lowers fertility, 229
low wet lands indicating, 236

Soil, mild alkali indicating, 236

mineral acids cause of, 239

nature of, 238

not harmful to roots, 248

not necessary to correct all, 249

organic acids cause of, 237

plants indicating, 234

prevalence of, 23?

roots not injured by, 248

sheep sorrel indicating, 235, 236

Truog test for, 234

unfavorable to bacteria, 230

weeds indicating, 235
a complex medium, 12
alluvial, defined, 15, 17
a reservoir, 98
bacteria, 171.

(See Soil bacteria)

affected by liming, 230

conditions favoring, 184

nodule bacteria, 180

non-symbiotic, 178

number in soils, 171

symbiotic 178
barley, 66
carried away, 9
chemical analysis of, 355, 356
collecting for, 358
for lime needs, 358
for nitrogen, 359
for organic matter, 359
for phosphorus, 359
for potassium, 360
how made, 358
uses of, 358

composition of, 29

affecting plant growth, 34
classes of, 14
classification, 14

on basis of origin, 15

on texture, 14

on type, 22-24

laboratory exercises, 26, 27
colluvial-soil, 15, 22
components of, 11
common meaning of, 11
cumulose, defined, 15, 16
depletion, defined, 84, 85

indicated by nitrogen analyses, 359
phosphorus analyses, 85, 250

in grain farming, 344

in stock farming, 345
descriptions of, 22
erosion, 17, 95, 283

a serious problem, 283

causes of, 285

causing loss of elements, 283, 350,
351

effect of, on irrigation, 284
on water power, 284

field studies on, 292

grazing in relation to, 286

injures crop production, 285

injuries resulting from, 283, 284

interferes with navigation, 284

in the United States, 17, 18, 283

kinds of, 286

on steep slopes, 285

pasturing in relation to, 286

prevention of, 287

problem in clay management, 324

soil organic matter relations, 287

projects on, 292

exhaustion. (See Soil depletion)
factor in plant growth, 47

396

INDEX

Soil fertility, defined, 79

affected by harmful agents, 255,
262

determined by chemical analysis,
355

diseases affecting, 255, 261

factors determining, 80
in maintaining, 271
to be considered, 355

grain farming and, 344

home projects on, 353

how to test, 80

illustrated, 82

indicated by crop yields, 80

in relation to fertilizing elements,

187, 206
fertilizers, 206
grain farming, 344
liming, 229, 231, 250
soil organisms, 171
stock farming, 345
systems of farming, 343

lowered by acidity, 229

maintained in grain farming, 344,
347

maintained in stock farming, 345

maintaining, 206, 271

not restored by liming, 250

problems on, 354

regulated by liming, 250

surveys, exercises, 353

unfavorable factors, 83

work problems on, 353
field studies on, 27, 46, 73
formation of, 5-9, 16-22, 40-45
forming processes, 6-7
from limestone, acid, 242, 248
glacial, defined, 15, 18
grains. (See Particles)
heavy, defined, 15
how described, 22
humid vs. arid, 44, 378
improvement, general, 87

crop rotations for, 263-274

by legumes, 180

green manuring for, 194, 195

home projects on, 368

in clay management, 321

in marsh management, 294

in sand management, 310

in silt loam management, 325

liming, first step in, 230

rotations best for, 274
in dry climates, 44, 378
in humid climates, 44
kinds of, 14, 15, 24
lacustrine, 15, 21
leaching of, 349, 351
light, defined, 15
loess, defined, 15, 22
mapping, 22-25

exercises on, 27
management increase crops, 2

in England, 2

in Germany, 2

in France, 2
marine, defined, 15, 21
mechanical compostion of, 15
mineral, defined, 41
moisture, 89-132. (See Soil water)

amount soils give up, 91

capillary rise of, 96

conservation of, 100, 313, 380

control of, 100

cultivation to conserve, 104,313,380

Soil moisture, factor in crop production,
92

forms of, 93

how held in soils, 93

importance of, in soil, 89

in relation to germination, 49

in soil medium, 12

laboratory exercises on, 105, 107

most important form of, 93

movement of, 95-98

mulches to conserve, 103, 104, 313

robbed by weeds, 104, 380

supply in soils, 98-100
mulch, cultivation to maintain, 104, 313

defined, 102

how conserves moisture, 103

laboratory exercises on, 105, 106 .

self-forming, 104

value during dry periods, 104
of, in dry-farming, 380

what constitutes a good, 103
needing phosphates, 199
needs, determining, 355

chemical analysis for, 355

factors to consider in, 355
of many kinds, 9, 14, 15, 24
of national interest, 1
organisms and fertility, 171. (See Soil

bacteria)
origin of, 5

our nation's problem, 2
particles, names of, 11

composition of, 29, 30

not plant food, 61

size of, 11, 12

porosity of, exercises on, 106
relation to seeds, 49
rich, defined, 66
rocks in relation to, 39
series, defined, 24
sour, 45, 229

source of mineral elements, 35
standards for comparing, 72
structure, defined, 13

and mulch formation, 104

destroyed by plowing, 54, 322

illustrated, 13

in clay management, 322

organic matter relations, 266

renewed, 54, 322

rotation relations, 266

seed-bed relations, 54, 135

tilth relations, 54, 322
survey, 22-25
temperature, 48, 109

and germination, 49

drainage relations, 48, 109

field studies on, 60

laboratory exercises on, 57, 59, 132

of clay soils, 322

marsh soils, 302
sands, 309

plant-growth relations, 51, 77
texture, defined, 13

basis for soil classification, 13

clay of fine, 13

drainage relations, 120

dry-farming relations, 378

factor in capillarity, £6

in water-holding, 98, 99, 102

fertility relations, 40, 72, 81

influence on capillarity, 96, 97

laboratory exercises on, 26

liming relations, 247

percolation and teepage relations, 95

INDEX

397

Soil texture, plowing relations, 142, 147, 148
sand of coarse, 13
seed-bed relations, 54, 135, 155, 322
soil classes determined by, 14

mulch relations, 103, 104
tilth relations, 54, 135, 322
unchangeable, 13
tight, denned, 112
transported, denned, 15
transporting agents, 15
tropical, 45
type, denned, 24
washing. (See Soil erosion)
water, 89

laboratory exercises, 105, ICG
(See Soil moisture)
weight of, 71

exercises on, 27
when formed, 5

why some deficient in K and P, 40
Soybeans, elements removed by, 63
for green manuring, 192
for sands, 312, 316
illustrated, 193
response to liming, 233
Spading disk harrow, 152
Spray irrigation, 130
Springs, why some dry up, 285
Stock farming, defined, 343

crop rotation in, 329
grain and, compared, 343, 344
popularity of, 344, 345
soil fertility relations, 343
Strawberries, elements removed by, 69
Stubble land, defined, 138
plows for, 141
plowing, 138

Sub-humid climate, defined, 42
Sub-irrigation, 130
Sub-main, tile, defined, 121
Subsoil, defined, 11

plant-food elements in, 72
tight, defined, 112
Subsoiling, 145, 147, 148

for sandy soils, 313
Subsurface drainage, 113

covered drains for, 116, 117
open ditches for, 115
Succession of crops, defined, 280
Sugar beets, desirable type, 55
a heavy feeder, 64
elements removed by, 62, 67
for marsh soils, 305
for sands, 317
need potash, 263
response to liming, 233
root system of, 68
rotation for, 2SO
where grown, 280
Sugar cane, rotation for, 280
Sulfate of ammonia, 196

of potash, fertilizer, 202, 203
Sulfur, defined, 30, 32

as fertilizing element, 33
function of, in plants, 56
Summer fallowing, defined, 153

in rotation, 277
Superphosphate fertilizer, 199
Surface drainage, defined, 112
plow furrows for, 114
surface runs for, 114
use of spade for, 114
run, defined, 114, 123

with tile, 123, 124
Swamp, defined, 39

Sweet clover, illustrated, 193, 323
for alkali soils, 258
for clay soils, 323
for green manuring, 193
for soil improvement, 193 323

Syenite, defined, 39

Systems of farming, 343

in relation to fertility, 343-353
of tile drainage, 121, 122

Tankage, fertilizer, 196
Temperature. (See Soil temperature)
Terracing, defined, 288
Testing soils for needs, 355-368

(See under Fertilizers)

(See under Lime)
Thomas slag, fertilizer, 197, 198
Tile (drain), defined, 117

drainage, defined, 117, 126

better than open ditches, 122
for alkali soils, 131, 258
for alkali spots, 44, 111
for "bogus" spots, 302
for heavy clays. 322
for irrigated lands, 131
for marsh soils, 110, 304
for slopes, 95, 111
gridiron system of, 121, 122
herringbone system of, 122
in relation to toxins, 262
natural system of, 120, 121
parallel system of, 121, 122
profitable, 124, 125
systems of, 121
tools for, 118

drains, explained, 117

better than ditches, 122
distance apart to lay, 119
how to cover, 119
how to make, 117, 119
how they work, 120, 124
laboratory exercises on, 133
must have fall, 117
protected outlets for, 122, 123
with surface runs, 123
Tillage, general discussion, 135

in relation to toxins, 262

objects of, 137

of clay soils, 212

of dry-farming lands, 378, 380

of marsh soils, 295, 297

of sands, 313, 315

principles governing, 137

relation to erosion, 287

seed-bed preparation, 138

tools, 136-169
Tilth, defined, 48

cultivation and, 135

factors determining good, 135
in development of good, 54

fertility relations, 356

field studies on, 60, 88

full meaning of good, 52-54

good, defined, 48

green manure and, 190

importance of good, 49

influences plant growth, 51

laboratory exercises on, 58, 59

liming favors, 230

of clay soils, 321

organic matter and, 266

poor, defined, 48

rotations to improve, 266

seeding and planting relations, 156
Timothy, elements removed by, 63

398

INDEX

Timothy, not a soil robber, 65

where grown, 275
Tobacco, a heavy feeder, 63, 64, 199, 203

phosphorus lost in growing, 267

response to liming, 233

rotations for, 276, 278, 280

stems as fertilizers, 202, 203

where grown, 277
Toxin theory of infertility, 261
Transported soils, 15
Tropical soils, 45
Truck crops and liming, 233
rotations for, 280
where grown, 281
True clay, denned, 41
Truog test for acidity, 234
Turnips, as feeders, 63, 67

for clay soils, 325

Unferilized plot, value of, 370

Vegetative period, defined, 49

activities in, 50

conditions and requirements, 50, 51
Velvet bean, for green manure, 193

for sands, 310, 312, 316

for soil improvement, 310
Vertical drainage, defined, 113, 124, 126

forms of, 124, 126
Vetch, for green manuring, 193
for sands, 316
rotations for, 280

Waste lime, 243
Water, a part of soil medium, 12
amount crops require, 89, 90
soils give up, 91
held by peat, 94

by soils, 93, 98
available water in soils, 98
capillary, defined, 93
conservation and control, 100
forms of, in soil, 93
free, defined, 93
gravitational, defined, 93
hygroscopic, defined, 93
laboratory exercises on soil, 105, 106,

133, 185

limiting factor in dry farming, 92
limits yields in humid regions, 92
movements of soil, 94
percolation of, 95

Water problems in farming, 92

required for germination, 49

required by plants, 89

too much is harmful, 109, 258, 260

why crops require, 89
Water-holding capacity of soils, 98, 99
how to increase, 102
laboratory exercises on, 107
Watermelon, response to lime, 233
Water requirement of plants, 90

factors influencing, 91
Water-table, defined, 113
Weathering, defined, 6, 172

agents, 6, 7

continues indefinitely, 9

products of rock, 41
Weed problem on marsh soils, 301
Weeders, defined, 168

illustrated, 168, 315

light harrows for, 168
Weeds, as moisture robbers, 104

controlled by liming, 230

controlled by clover, 78

exercises on, 87

field studies on, 107

for green manure, 195

how to kill, 164, 166

killed by shading, 78
Weight of soils, 71
Wheat, elements removed by, 63

production on decline, 1

rotation for, 275-277

where grown, 276, 277
White alkali, defined, 44

grubs, 255
Wind, a transporting agent, 15, 22

a weathering agent, 6

breaks in sand farming, 314
Winter wheat, rotations for, 267, 279

where grown, 276
Wire worm, 255
Wood ashes, as fertilizer, 202, 203

for acid peats, 204

for marsh soils, 301

for mixed fertilizers, 211

Yeast plants, illustrated, 171
Yield, affected by temperature, 51

relation to cost expense, 369
to profits, 369

relatively low, 2

YC

UNIVERSITY OF CALIFORNIA LIBRARY