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AN INTRODUCTION TO
AGRICULTURE
AN INTRODUCTION
TO
AGRICULTURE
BY
A. A. VWPHAM
TEACHER OF SCIENCE, STATE NORMAL SCHOOL
WHITEWATER. WISCONSIN
AND
G. A. SCHMIDT, M.S.
TEACHER OF AGRICULTURE, STATE NORMAL SCHOOL
WHITEWATER, WISCONSIN
NEW EDITION THOROUGHLY REVISED.
NEW PROBLEMS AND QUESTIONS.
D. APPLETON AND COMPANY
NEW YORK CHICAGO
rat
COPYRIGHT, 1910, 1919, BY
D. APPLETON AND COMPANY
‘
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~
219043
a
— \ 4 »' 4
y
PRINTED IN THE UNITED STATES OF AMERICA
Pg
PREFACE
The progress that has been made in the teaching of
agriculture and the emphasis given to the subject
through the pressure of the world war have made a re-
vision of the ‘‘ Introduction to Agriculture” desirable.
When this book was published eight years ago, few of the
states of the Union had published courses of instruction
in agriculture. Most of the states have now done so and
the authors have compared these courses and selected the
salient points as a basis for an elementary book. Any
state will find this book a text:admirably fitted to its
required course of study in agriculture.
The high cost of living has turned the attention of
many people towards the raising of poultry and garden
products; the book will be found especially strong in
these two particulars and will therefore serve as a val-
uable reference book in public libraries and in homes
of amateur farmers. Throughout the volume special
emphasis has been given to those phases of agriculture
in which a child is most easily interested and in which he
can most readily become useful. The new chapter on
home projects directs him in such work.
The book contains many questions and problems,
mostly new, and of a kind that the practical student
Vv
v1 ) OPREFACH
ought to be able to answer. These questions and prob-
lems are not directly answered in the text but require the
student to think, investigate, or act.
Grateful acknowledgment is made for cuts furnished
us by the United States Department of Agriculture, by
colleges of agriculture and by business concerns inter-
ested in agriculture. Credit has in all cases been given
unless by accident it has been overlooked. If any such
omissions have occurred the authors will be glad to make
the necessary correction in subsequent editions if their
attention is called to the omission.
A. A. Upnam.
G. A. ScuMipT.
CHAPTER
iE
II
EL
ROVE
XVII
XVIII
XIX
XX
XT
XLT
XXII
CONTENTS
IMPORTANCE OF THE STUDY OF AGRICULTURE .
Tue NATURE oF PLANTs .
THE Soin
WATER IN THE SOIL
TILLAGE
ELEMENTS OF PLANT Foop IN THE SoIL
Som FERTILITY
LreGuMinous Crops AND RoTaTION oF CRops .
Corn
WHEAT, BarteY, RYE, anpD Oats
Forace Crops .
OTHER Farm Crops
SEEDS
PLant ENEMIES
THe FarRMeEr’s FRIENDS: Birps, Toaps, BrEEs
GARDEN Crops
Home GARDENS
PROPAGATION BY CUTTINGS AND BY OTHER
MEANS
THE ORCHARD .
SPRAYING AND SPRAYING SOLUTIONS .
FEEDING ANIMALS
POULTRY
CATTLE .
203
eke
. 128
4136
151
,ch61
. 168
we
78S
. 203
. 214
erp!
. 248
CHAPTER
XXIV
XXV
XXVI
XXVIT
XXVIII
XXITX
CONTENTS
PAGE
Mik ann Ivs' Propuers:. <. ba 2 eee
TIGRS ES Nery ele oh ta dec eal Mai ict Atte Soa rr
SWINE AND SHEEP ee RM em RS
Goop Roaps — Forestry — HomME AND ScHOOL
GROUNDS AR ee ee
SCHOOL-HOME’ PROJECTS’ .) 4. “sroe. 2 Saas
SCHOOL. GARDENS? 4) (ag co! 2 Oe
APPENDIX. (4006 (6 G04 oop ab?
AN INTRODUCTION TO AGRICULTURE
CHAPTER J
IMPORTANCE OF THE STUDY OF AGRICULTURE
1. Why Agriculture Should be Studied.— Agri-
culture touches the life of all of us. The three great
needs of a human being are food, shelter and clothing.
With the exception of sea foods and salt most of our
food is produced by the farmer. Nearly all our cloth-
ing is made from cotton, wool, silk and leather which
are the products of agriculture. Our houses are
largely built of wood which grows on the land and even
now in some parts of the world requires attention like
other crops. While many of the pupils who study
agriculture in school never become farmers, an increas-
ing number are finding that they have need of what
agriculture teaches. Every one should know some-
thing about the production and the qualities of the
different foods he eats. In rural schools, especially,
pupils need to learn both the reasons for the work
which is done on the farm, and the ways in which suc-
cessful farmers do it.
Schools to-day are trying everywhere to give pupils
knowledge which will be of practical use to them in
life; and, from this point of view, no study is more
1
2 AN INTRODUCTION TO AGRICULTURE
important than agriculture. No pupil comes to under-
stand the subject by crowding his mind with facts or
by memorizing his text book. He must observe the
things he is studying about, wherever he finds them —
in the fields or on the home farm. These facts of agri-
culture are always about him, and are full of interest-
ing matter for thought and for careful study, so that
the subject of agriculture offers any pupil plenty of
opportunity for the mental discipline which his grow-
ing mind needs, even while at the same time, it gives
him knowledge he can put to practical use.
2. Relation Between Success of Farmers and
Their Education.— On reading the preceding topic,
the thought may arise, ‘‘ The more education a man has,
the poorer farmer he will be.” If education means, as
it formerly did, a knowledge of the classics, ancient
history, and the higher mathematics, the thought may
very likely be true. But the word education, in this
connection, means gaining the knowledge and the judg-
ment regarding the underlying principles by which the
farmer works, in order to get successful results. Any
sensible boy readily can see that knowing the princi-
ples of raising and feeding dairy cattle, and practice
and skill in the use of the Babcock test, will lead to
more success in dairying; that a knowledge of plant
growth will lead to a more productive orchard; or that
knowing how to improve plants and make the soil
more fertile, will lead to the production of bigger and
better crops. More than that, any boy or girl who has
studied agriculture should be able to conduct a home
garden project, or any other farm project, and get
IMPORTANCE OF THE STUDY 5)
better results than he would if he had not studied agri-
culture.
3. Increased Production Due to Better Knowl-
edge.— There are on record many cases, where a per-
son, having more carefully appled the underlying prin-
ciples of agriculture, has obtained unusually good re
sults in the very places where before, when these princi-
ples have been ignored, the results have been complete
failures. One of the most striking of these occurred
on * Poorland Farm,” in southern Illinois. In 1903
Prof. Cyril G. Hopkins bought this farm of 300 acres
for less than $20 an acre. On a 36 acre-field of this
farm, which was so poor that it had been abandoned,
he raised, in 1913, 1278 bushels of wheat, or 354%
bushels to an acre. He got this result in a very prac-
tical and economical way; he spent $1.75 per acre each
year for the materials with which he improved the
field.
Here is another case —one which shows what in-
telhgence did for an Iowa farmer. In three years, by
keeping dairy records, by weeding out poor cows, and
by proper feeding and management, this farmer in-
creased the average yearly yield of butter fat of his
herd from 207.7 lbs.. to 341.98 lbs. This made the
products of each cow worth $75 more a year to him
than the cost of keeping her, while, at the beginning
of the three years, each cow had been worth only
$22.12 more than the cost of her keep. Thus, by put-
ting to practical use his knowledge of dairying, this
farmer increased the average net income of each of his
cows 39 per cent.
4 AN INTRODUCTION TO AGRICULTURE
Eighteen Ohio farmers kept records of their flocks
of hens for one year. The best flock of 100 hens showed
a profit of $247. over the cost of feed, and the poorest
flock showed a profit of only $15. Here again better
knowledge of the underlying principles of poultry
management made a difference in net income of $222
in favor of the best flock.
4. Growth of Agricultural Instruction.— The last
fifteen years has seen a remarkable development in the
teaching of agriculture. This development has been
due largely to the activity in agricultural interest
aroused by the United States Department of Agriculture
and by the State Colleges of Agriculture. Under their
guidance, agriculture, the oldest industry of man, and
the most necessary for sustaining life, has reached a
stage where its importance is appreciated by every
thoughtful man. No intelligent citizen to-day is en-
tirely ignorant of the science of agriculture.
As a result of this aroused interest, there has de-
veloped a mass of good writing on agricultural sub-
jects. Hundreds of books on all phases of agriculture,
written by trained specialists, are found in public
libraries. The circulation of agricultural periodicals
is wide-spread throughout the country; and the Govern-
ment, State Agricultural Colleges and Experiment Sta-
tions, as well as railroads, and private business organiza-
tions, are constantly putting forth the results of their in-
vestigations in the form of bulletins. No student in the
public schools of America to-day can afford to overlook
or slight a subject of such universal importance as
agriculture.
IMPORTANCE OF THE STUDY 5
QUESTIONS AND PROBLEMS
1. Give at least three reasons why agriculture should be
taught.
2. Give some instances where a better knowledge of farm-
ing has given better results.
3. What should a man know who wishes to buy: good po-
tatoes? Good corn? Celery? Meat? Butter?
4. What do you know about the growth of the agricultural
instruction in the high schools of your county? In your
state agricultural college ?
5. What are some of the things your state college of agri-
culture has done which have benefited the farmers in your
community ?
6. What agricultural bulletins and periodicals does your
father receive? In what articles in them are you most inter-
ested ?
7. Do the grade cows in your community give better milk
and butter fat yields than the scrub cows?
CHAPTER II
THE NATURE OF PLANTS
5. Importance of Plants.— Plants are very impor-
tant, for without them animals could not live. Animals
depend upon plants for
their food. A cow eats
grass and changes this into
milk and meat. We eat
both plant and animal
matter but the animal mat-
ter we eat, such as meat,
eges, milk, etce., comes
from animals that have
made these substances
from plants. Later we
shall learn how all green
plants can make, from the
materials they absorb from
the soil and air, the sub-
stances we commonly call
foodstuffs, such as protein,
TYPICAL PLANT (Columbine) sugar, starch, and fat.
Showing. @. Huwer; 70. leat, No animal can make these
c, stem; d, roots
foodstuffs but all green
plants can.
6. The Parts of a Plant.— Most plants have roots,
stems, leaves, flowers, fruits, and seeds.
6
Pon NATURE, OF PLANTS it
Roots.— The roots reach out through the soil, hold
the plant in place, and absorb raw food material for it.
They conduct the absorbed liquids up to the stem of the
plant. In plants which live more than one year, the
roots also act as a storage house for reserve food ma-
terials. Large roots
branch into smaller
roots, until they be- Wises y (
come fine, delicate hin?
rootlets. The tiny QS IL. vd.
rootlets bear the still Aan b
finer root hairs.
These root hairs are
so very fine and deli-
eate that they appear CROSS SECTION OF A ROOT
Pere brid fuze, ovine Un Seat Hake. 6 Bae te
on young seedlings.
When corn, oats, or other seeds are tested for their
germination power the root hairs may be seen easily.
The root hairs are very important, as it is they which
_absorb from the soil the substances which the plant uses
in making food.
Stems.— The stem is the framework on which leaves,
flowers and fruits are borne. It may be very short and
thick as the “ crown ”’ of the turnip or beet; it may be
very slender and light as in grains, or it may be large
and strong as in the trunk of a tree. By means of
numerous tubes the stems also connect the leaves with
the roots. The water and other raw food materials
absorbed by the root hairs must be taken up into the
leaves where these raw food materials are manufactured
g§ AN INTRODUCTION TO AGRICULTURE
into plant food. Some of this manufactured plant food
must then be carried back from the leaves down to the
stem and roots, so that these parts may be nourished and
grow. Roots and stems, or any other parts of a plant,
cannot be nourished by the raw food materials absorbed
from the soil, until these materials are made into manu- |
factured plant food in the leaves.
Leaves.— The leaves of plants are generally broad,
thin and green. The leaves are the factories in which
the raw food materials, gathered by the roots and by the
leaves themselves, are made into plant food for the use
of the entire plant. The large part of the leaf is the
blade. Running through the center of the blade is the,
thickened midrib, and branching out from the midrib
are the veins.
The midrib and
veins have vessels
which are in di-
rect communica-
tion with the ves-
vels of the stem.
Flowers. — In
order to get a clear
idea of the parts
of a flower, sepa-
FLOWER OF PEONY.—SHOWING THE FOUR SETS ‘ ;
OF FLORAL ORGANS rate into its parts
k, the sepals, together called the calyx; ¢, .
the petals, together called the corolla; a, the a simple flower
numerous stamens; g, the two carpels, which like a morning’
ome
contain the ovules.— Strasburger.
glory or a single
petunia. You will notice first a sort of a cup where
the flower rises from its stem. This is the calyx. It
Peat NATURE OF (PLANTS 9
is generally green and often divided into parts, like
little leaves. Inside this green calyx cup is the corolla,
the colored or showy part of the flower which attracts
our attention. The divisions of the corolla are called
petals. In the heart of the flower you will find a
eluster of slender threads, called stamens, each with an
enlargement containing a fine powder, called pollen.
In the very center of the flower, surrounded by the
stamens, is the pistil or seed forming organ. ‘This is
usually largest at the base, just above the point where
it connects with the stem, and it is in this enlarged
part that the seeds form and develop.
7. Pollination and Fertilization.— In order that
a seed may be formed in the seed organ of a flower, it
is necessary that pollen shall fall or be placed on the
upper part of the pistil. This transfer of pollen from
the upper part of the stamen to the upper part of the
pistil is called pollination. Sometimes the wind does
this work for the flower, and sometimes an insect.
When the upper part of the pistil is ready to receive the
pollen, it is usually sticky so that the pollen will cling
to it. The pollen grain soon begins to germinate and
sends a shoot down into the enlarged part of the pistil,
or ovary, where it reaches the forming seed. ‘The con-
tents of the pollen grain mingle with the contents of the
forming seed and make a fertilized seed. The process
is called fertilization. If a forming seed has been fer-
tilized it will grow and develop into a seed; if not, it and
all the parts of the flower will wither and die. Miss-
ing kernels of corn are a common example of forming
seeds which have never been fertilized.
10 AN INTRODUCTION TO AGRICULTURE
8. Fruits and Seeds.— When a flower has been fer-
tilized, the ovary, and in some cases, adjacent parts,
continue to grow and develop into the fruit. When a
flower is not fertilized, no fruit is formed. A mature
or ripened ovary, together with its contents, always is
the fruit of a seed forming plant. Sometimes, as in the
case of corn or oats, the seed constitutes the entire fruit ;
and often, as in the apple, the seed is but a very small
part of the fruit.
Seeds.— The fruit continues to grow until the seeds
are ripe. At first the seeds contain much water and
they must be dry before they can be stored away safely.
This is why corn and grains are shocked in the field at
harvest time, and seed corn is gathered and hung where
it will dry quickly and not freeze while it contains so
much water. After seeds are dry, freezing does not
injure them. ‘There are many different kinds of seeds,
but all of them contain both a little immature plant,
called the germ, and some stored up food. In a bean
seed the little plant is easily seen.
Soak some lima beans and some kernels of corn in water
for a few days. Then remove the seed coat of the bean and
notice the little root projecting up between the halves of the
seed and the little leaves between them. Cut the kernels of
corn lengthwise through the center and notice the little
stem and root.
Classes of Seeds.— There are two common classes
of seeds. The bean is a good example of one class and
corn of the other. If you try to divide the bean seed,
you will see how easily it separates into two halves.
Each of these halves is a thickened seed leaf and is
Tae NAR OF PLANTS is
called a cotyledon. Projecting out between the cotyle-
dons is a small pointed root-like structure and between
them is a pair of little leaves. These parts are all at-
tached to each other and form the new plant when the
seed germinates. The corn seed differs from the bean
in that it has only one cotyledon, in which the little root
and leaves are imbedded.
9. How a Plant Grows.— You have seen how a
plant begins to grow from the seed. It sends a shoot
upward toward the light and a root downward into the
soil. The upward shoot becomes the stem and leaves,
and the downward shoot, the root. The root, as it
grows, soon divides into many branches which penetrate
the soil in all directions.
Place some large seeds, as beans, peas and corn, in water.
Put some in damp sand and sawdust. Watch their develop-
ment and continue to study the little plants as they grow.
10. How the Plant Gets Its Food.— The plant
starts its life by feeding on the manufactured food
stored in the seed. But as soon as its leaves have
reached the sunlight and the roots have developed root
hairs, the plant absorbs the raw materials out of which
it makes its own food. Air, water, and mineral salts
in the soil water are the plant’s raw food materials.
The green tissues of a plant have the power to com-
bine the water and the mineral substances from the soil,
and the gases from the air, to make food for the plant.
This process can take place only in the sunlight and
the leaves are the principal organs manufacturing this.
food. In the process the leaves return to the air,
12 AN INTRODUCTION TO AGRICULTURE
through their breathing pores, both a gas which we call
oxygen, and water, in the form of vapor.
11. Conditions of Growth.— In order to grow well,
) the plant must have the
=e proper conditions of
——— Sie . .
a heat, water, air, light,
ee and raw food. Until
Er ZS :
me SE ~=©60 the ~ weather is warm
2
nee = most seeds do not even
S sprout. Light is very
essential to the life of
plants; in the dark they
stop growing or grow
only a little and weakly.
A certain amount of
water must be in the
ROOT TIPS OF CORN soil within reach of the
Showing root-hairs and their position in - :
reference to the growing tip plant, or it will wither
cen
. - ar
ee E eal
neeRetenitt
and die. There must
be free circulation of air, and the proper amount and
kinds of raw food materials must be in the soil.
In two wide-mouthed bottles place some damp sand or saw-
dust. After soaking a handful of oats in water over night,
place half of the seeds in each bottle. Cork one bottle very
tightly, and leave the other open. Watch the results. How
ean you account for the difference?
QUESTIONS AND PROBLEMS
1. Give a list of flowers pollinated by insects. By the
wind.
2. Would it be better to bunch the corn in a garden or
plant it in a single row? Explain.
Tae NATURE OF PLANTS 13
8. Make a list of plants having one cotyledon. Having
two.
4. The seeds of what plants are used for the manufacture
of oil? Of starch?
5. Draw a longitudinal section of some flower and label
all parts.
6.. Why cannot the plant use stones for food materials?
7. In what form is the raw plant food usually found in
the soil? Is this good or bad?
8. In transplanting plants why should they not be pulled
out of the ground?
9. Name the plants whose seeds are especially rich in pro-
tein.
CHAPTER III
THE SOIL
“The soil is the greatest natural resource of the Na-
tion.”
12. The Composition of Soils.— By soil we mean
that part of the earth’s crust in which plants grow. It
is a loose, decomposed layer of mineral matter mixed
with more or less vegetable and animal matter. The
soil furnishes plants with water and raw food materials,
and gives them an ideal place in which to spread their
roots so that they may easily support the parts which
live above the ground. The soil varies greatly in depth.
In some places it may
be only a few inches
deep, and in others,
many feet. The top
layer of the soil is
often called the top or
surface soil, and it is
generally darker in
. color than the layer
SOIL FORMED FROM ROCK UNDERNEATH beneath it, ealled the
a, soil with grass growing in it; b, sub- : :
soil, coarser and more rocky; c, coarse, loose subsoil. The subsoil
rock; d, rock in layers, cracked. d changes : 1 1
to c, c changes to b, and b to a. Varies greatly -
depth and _ extends
down to the underlying layer of bed rock. The top soil
14
PHE SOLL 15
is darker than the subsoil because it contains more
vegetable matter. The subsoil is generally harder,
colder, and less suitable for plant growth than the top
soil.
13. Origin of Soil Materials. All the mineral
particles in soils have been formed from the breaking
down or crumbling, and decomposition of rocks. These
processes never cease in the soil and are continuously
leaving rock particles of various sizes. In many soils
there is a gradual grading from fine particles on top,
down through coarser and coarser materials until the
solid rock is reached. The different agents which
nature uses to bring about the breaking down and the
decomposition of rocks are: — water, frost, changes of
temperature, wind, plants, animals, gravity, acids, and
the gases, oxygen and carbon dioxide.
Refer to your geographies and find out how each of these
agents accomplishes this work.
14. Source of Organic Matter.— Plants on the
surface of the ground, and also their roots, wither and
die, and some of the materials they contain slowly be-
come a part of the soil. The original richness of the
pioneer soils of the western prairies was due to the
benefits of the vegetable matter which the roots and
tops of the prairie grasses had been forming for many
years.
The animal matter in the soil comes from the re-
mains of animals which have died. The amount of
this is always very small. The dead animal and vege-
table matter, accumulating both in the soil and on the
16 AN INTRODUCTION TO AGRICULTURE
surface decays and gives the dark color to our soils.
We call this decaying animal and vegetable matter
humus. Quite often the term organic matter is used
in speaking of soils. This term refers to all the animal
and vegetable matter. It includes not only all the
humus in soils but also the plant and animal matter not
sufficiently decayed to be called humus.
15. Formation of Soils.— The soil on which your
schoolhouse is built has been formed in one of two
ways. The soil particles may have been brought to
the place by some agent such as a glacier, running
water, the wind, gravity, or by voleanic action; or else
the particles were formed by the breaking down of the
solid rock which once covered that particular spot.
Refer to your geographies and read again just how these
agents have formed, or transported and deposited soils.
16. Classes of Soils.— Most soils are made up
chiefly of four different kinds of materials — sand, silt,
clay, and humus. Sand, silt, and clay are the mineral
parts of the soil; the coarsest of these is sand, the finest
is clay, while silt is finer than sand but coarser than
clay.
Sandy Sotls— When you rub sandy soils between
your fingers, you find that they feel gritty. They drain
and dry out quickly because the pore spaces between
the particles of sand are large. Air circulates freely
in them and they warm up quickly. Sandy soils are
adapted to early crops.
Clay Soils.— Clay when dry and loose is like a very
fine powder. Clay soils are just the opposite of sandy
THE SOIL 17
soils. The pore spaces between the particles are ex-
ceedingly small; in fact, so small that the tiny particles
of clay can easily unite themselves into a sticky mass.
Clay soils drain and dry slowly and admit little air.
When they dry after rains, they are compact and often
form on the surface a hard crust which makes it diffi-
cult for the air to circulate in them. Clay soils are
spoken of as cold soils. They are best adapted to the
small grains and grasses.
Loam Soils.— When sand, silt, and clay are found
in a soil so evenly mixed that there is not much more
of one kind of soil than of another, we call the soil a
loam. Loam soils are generally considered the best, be-
cause they may be used to grow to advantage all. of
our common crops.
They have none of
the disadvantages of
sandy and clay soils,
and still they have
most of their good
qualities. There are
o> Gb .
i
SOIL Piaeene HUMUS
many kinds of loam Notice how hard and compact this soil
soils, such as: silt ae sed of the International
loam, sandy loam,
clay loam, ete.; in these the silt loam contains slightly
more silt, the sandy loam, slightly more sand, than is
found in a loam soil. |
Marsh Soils.— There are also soils which contain so
large a part of organic matter that they are very black
in color. Once upon a time these have been marshes,
but they are now drained, and have become what is
18 AN INTRODUCTION TO AGRICULTURE
known as muck and peat soils. Peat soils contain more
organic matter than muck soils, and both kinds, when
: properly drained,
generally make good
soils.
Inght and Heavy
Sovls.—If we had
equal volumes of
sand, silt, and clay,
all in a loose and dry
condition, and should
weigh them, we
would see that the
sand would weigh the most, and that the clay would
weigh the least. Usually, however, you will hear a
sandy soil spoken of as light and a clay soil as heavy.
These terms do not refer to the actual weights of soils,
but to the ease with which they are worked. Sandy
souls are easier to plow and to cultivate than clay soils,
as the “ pull” required is less.
17. Other Constituents of Soils.— Besides mineral
and organic matter, soils also contain water, air, and
many kinds of living organisms, such as worms, insects,
molds and bacteria.
SOIL RICH IN HUMUS
Note the difference between this soil and
the hard, baked soil.— Courtesy of the In-
ternational Harvester Company.
EHarthworms.— Earthworms are very beneficial to
soils, because the channels or burrows they make allow
water and air to penetrate more rapidly. Earthworms
help drain the soil and by means of their channels give
roots an easy chance to penetrate into the harder
subsoil. ‘
Sow Bacteria.— Good soils literally teem with bac-
THE SOIL 19
teria. There are both good and bad bacteria in the
soil. Some of the good bacteria act upon the organic
matter and change it in such a way that much of the
insoluble matter which composes it, 1s made soluble.
This process sometimes is called decay. From this
decay, nitrogen, one of the necessary raw foods of
plants, is set free in such a way that the plant can use
it for raw food.
Other soil bacteria live upon the roots of leguminous
plants, as on the bean, clover, alfalfa, ete. These also
are good bacteria, because they make use of the nitro-
gen in the soil air and change it into a nitrate, a soluble
compound which the plant, upon whose roots the bac-
teria lives, uses for a raw food material.
Soil also contains bad bacteria. These bad bacteria
are most numerous and active in wet soils. The bad
bacteria do not aid in making raw plant food ready for
the use of plants.
Air in the Soil.— Roots of plants, germinating seeds,
worms, insects, and bacteria, all need air to live. Air
in the soil is necessary also because the gases it con-
tains, oxygen and carbon dioxide, help in the decom-
position of substances in the soil.
Humus in Soils.— Humus is one of the most impor-
tant constituents of all our soils, and without humus
no soil is of much value. A soil containing little or no
humus is generally barren. Humus adds to the soil
raw plant food, principally nitrogen. Humus not only
feeds the bacteria in the soil, but it is their principal
source of food.
18. Humus Forming Materials.— Manure forms
20 AN INTRODUCTION TO AGRICULTURE
a great deal of humus, and this fact makes manure of
more value to the farmer than commercial fertilizers
in the improvement of most poor soils. Sod, stubble,
and roots of crops, weeds, corn stalks, straw, and in
fact, all vegetation, add humus to the soil. This shows
us why manure should never be allowed to lie in piles in
a barnyard for a long period of time until it has de-
composed and lost much of its value as a fertilizer, and
why straw stacks and corn stalks should never be
burned, but be made use of by farmers to improve their
land. Another excellent way to add much humus form-
ing material to a soil is by growing. a crop which is
adapted to being plowed under; such crops planted for
such a purpose are called green manure crops.
1g. Soil Acidity When we mentioned the differ-
ent agents by which soil is
made, we spoke of acids.
Vinegar and lemon juice are
good examples of acids. The
greater part of many acids is
water, and this is also true of
vinegar and lemon juice. If
we put a little piece of old
plaster in a glass and cover it
with vinegar or lemon juice
we shall see little bubbles
Courtesy of the Soil Improve-
Fertilizer Association.
and if we put the glass close
to our ear we shall hear a sizzling noise.
Try this experiment.
THE SOIL 21
If we put a drop of vinegar or lemon juice on a
piece of blue litmus paper we shall see the blue paper
turn red.
Any druggist will give you a few strips of litmus paper
with which you can try this experiment.
All substances which act toward old plaster and lit-
mus paper as the vinegar and lemon juice do are called
acids. The small roots of plants contain an acid, some
of which is always entering the soil.
Prove this by crushing a little root against a piece of blue
litmus paper.
The decay of organic matter and the decomposition
of certain mineral soil particles also add acids to the
soil. The gas carbon dioxide which occurs in the air
makes a mild acid when it unites with water and some
of this acid enters the soil. If there are any substances
in the soil which have the same properties which the
piece of plaster has, these soil acids act upon them just
as the vinegar or lemon juice acts upon the plaster in
the glass. If there is enough of these materials pres-
ent in the soil, the acids will soon be destroyed. Lime-
stone and other forms of lime have the same proper-
ties which the plaster has and this is why these ma-
terials are often put upon an acid soil to destroy its
acidity or to sweeten, it.
20. Testing Soils.— It is a simple matter to test
soils for acidity. Take a handful of wet soil and form
it into a ball. Break the mud ball into halves, and
place a piece of blue litmus in the center on one of the
halves, and cover with the other half. After five
22 AN INTRODUCTION TO AGRICULTURE
minutes break the ball, and if the paper now appears
pink, the soil is sour. If you need water to moisten
the soil, use soft water which has no effect upon the
IN MOST CASES LIME SHOULD BE APPLIED TO THE LAND AFTER IT IS
PLOWED AND PARTLY FITTED.— The Country Gentleman published by the
Curtis Company, Philadelphia.
litmus paper. Handle the soil as little as possible as
the hands generally contain an acid which changes the
color of the paper.
Test soils with litmus paper.
We also can tell easily if a soil itself contains lime
by adding vinegar or hydrochloric acid to it as we did
to the plaster in the glass.
THE SOIL 23
Try this experiment. Bubbling and sizzling indicate the
presence of some form of lime.
We can safely say that the majority of our farming
soils contain too much acid and too little lime for the
greatest crop ylelds. In every state the liming of soils
is a regular farm practice.
21. Disadvantage of Acid Soils.— The acid in the
soil checks the growth of our good bacteria which make
nitrates from the humus and from the soil air; in many
places the actions of bacteria almost stop because of the
large amounts of acid in the soil. The lack of lime
also has an effect upon the physical structure of the soil
so that it is apt to be more compact than if lime were
present.
22. Appearance of Acid Soils.— Acid soils often
bear certain outward signs which show that they are
acid, such as the failure of clover, alfalfa, and other
legumes to grow well; often these crops will not make
any growth at all on acid soils. The appearance of
sheep sorrel, moss, and horsetails is also an indication
that the soil is acid. Liming the soil destroys the acids,
and when this is done, we say the soil has been sweet-
ened, because the soil acids have a sour taste just as
vinegar and lemon juice have.
To each of two tumblers, three-fourths full of water, add
and stir a tablespoonful of soil. Add enough lime water to
one tumbler to fill it. Note how the settling and clearing
of the two tumblers differs. Adding lime to a soil granulates
it as the lime did in this case.
23. Soil Surveys.— The United States Government
in connection with the State Agricultural Colleges, is
94 AN INTRODUCTION TO AGRICULTURE
making soil surveys in all the states. A soil survey is a
very careful study of the soil, made in the field and
usually considers the following: —
Origin and formation of the soil.
The lay of the land.
Whether originally timbered or prairie.
Structure and depth of soil.
The physical and chemical composition.
The kind of soil — class and type.
The drainage.
The value, based on productiveness,
The reaction.
Suggestions for improvement.
In brief, a soil survey is an inventory of a soil and is
intended to be of practical help to farmers so that they
may, without any cost, be able to study how to make
the best possible use of their soils. Each soil survey
usually covers a county; that is, the county is the unit.
A map showing the topography, and by means of dif-
ferent colors, the soil types, accompanies each bulletin
containing a survey. ‘These surveys may be obtained
from the State Agricultural Colleges or from the United
States Department of Agriculture at Washington. Not
all counties in the United States have been surveyed,
but the plan is to make a survey of every county which
has much agricultural land and which is fairly well
populated.
Each school should inquire from its State Agricultural
College whether its county has been surveyed, and, if it has,
obtain the soil survey bulletin and map. There is no better
THE SOIL 25
way to get as large an amount of valuable information about
the soil of any particular county as by studying its survey.
QUESTIONS AND PROBLEMS
1. How deep is the surface soil in your garden ?
2. What do you suppose was the origin of the surface soil
you removed to get its depth ?
3. Is the soil in your garden a clay, sandy, or loam soil ?
How do you know?
4. Have you ever seen any muck soils in your vicinity?
Describe their location.
5. What do you suppose is the cause of the bogs so often
seen on muck land?
6. Would a rock crumble more where the climate is even
or where it is changeable?
7. What are your reasons for believing that the surface
soil is better than the subsoil ?
8. If 96% of a sample of limestcne may be dissolved and
earried away by water how many cubic feet of such limestone
would make 12 cubic feet of soil?
9. Do the farmers in your community make a regular
practice of liming the soil?
10. Has a soil survey been made of your county ?
Bulletins for Sale by Superintendent of Documents, Wash-
ington, D. C.
Soil Surveys 15 cents each. Send for list of your state.
Also issued by the State Agricultural Colleges.
Soils of the United States, Soils Bulletin 55, 45 cents..
Study of Soils of the United States, Soils Bulletin 85, 25
cents..
Soil Erosion, Soils Bulletin 71, 35 cents.
Some Organic Soil Constituents, Soils Bulletin 88, 10 cents.
Important American Soils, Yearbook Sept. 563, 5 eents.
26 AN INTRODUCTION TO AGRICULTURE
Farmers’ Bulletins.
Liming Soils, F. B., 257.
Renovation of Worn-Out Soils, F. B., 245.
Management of Muck Soils in Ind. and Mich., F. B., 761.
Management of Sandy Farms in Ind. and Mich., F. B., 716.
A Simple Way to Increase Crop Yields, F. B., 924.
The Principles of Lining Soils, F. B., 921.
CHAPTER IV
WATER IN THE SOIL
24. The Importance of Water to Plants.— With-
out plenty of water in the soil, plants cannot thrive.
You already know why this is so. Water itself is a
raw food material, and in the water is also dissolved
all the other raw food materials which a plant takes
from the soil. More than that, water is necessary to
conduct the raw food materials from the roots to the
leaves and to conduct some of the manufactured food
from the leaves back to the stem and roots.
25. The Movement of Water in the Soil.— Part
of the water that fails during a rain sinks into the soil
in the little pore spaces between the soil particles. You
know how the water sometimes runs through the soil
in a flower pot and comes out of the hole at the bottom.
If the soil is dry, and you give the plant only a little
water, none of the water runs out, but all of it is held
among the soil particles, which now look moist instead
of dry. That water which sticks to the particles of soil
is called film or capiulary water, because it surrounds
the particles and also partly fills the small pore spaces,
or capillaries, between them. The water which runs
through the soil is called free water because it is free to
drain. The water that comes into a hole which is being
dug in the ground, is free water.
27
28 AN INTRODUCTION TO AGRICULTURE
Hvaporation.— If we add considerable water to a
flower pot, the free water will run out through the hole
in the bottom. The soil on the top soon begins to dry
out. The water in this top soil passes off into the air
in the form of vapor. We call this process evaporation
and we say the water evaporates.
How Water Rises in the Soil.— When the water from
the upper surface evaporates, the film of water sur-
rounding these upper particles gets thinner. The film
of water is thickest
nearest the bottom
and this is why the
bottom soil is always
more moist than the
surface soil. Slowly
the water from the
lower surface begins
to creep up around
_ the soil particles, just
as the oil creeps up a lamp wick, or as ink moves up a
piece of blotting paper. Each particle, however, will
continue to be covered with a film of water and when this
reaches its thinnest stage, upward movement ceases.
When roots take water from the soil, the films of water
in contact with the roots get thinner, and this causes a
movement of water toward the roots, just as in the case
of evaporation, there occurred.a movement toward the
upper soil particles. We call the force which brings
about this movement of water capillary attraction.
EXPERIMENT SHOWING CAPILLARITY
Take two glasses, fill one with water, and place them side
by side. Place one end of a lamp wick in the glass contain-
WATER IN THE SOIL 29
ing the water, as shown in sketch, and let the other end hang
into the empty glass. Watch the results.
Increasing Upward Movement of Water.— It is pos-
sible to increase the upward movement of the water in
soils and to draw up water from the subsoil by keeping
the soil particles fine and close together. Naturally,
then, in a well prepared seed bed there would be more
3 Fs fhe ATE oY rea OT it Hs
Ne
APPARATUS TO TEST THE POWER OF SOILS TO TAKE UP MOISTURE FROM
BELOW.— Farmers’ Bulletin No. 408, United States Department of Agri-
culture.
water near the surface than in a seed bed which is not
well prepared, but cloddy and loose. The upward
movement of water may also be illustrated with lamp
chimneys, as shown in the sketch.
To the bottom of three lamp chimneys securely tie a piece
of cheese cloth. Fill one chimney with gravel, one with
sifted sand, and one with any fine soil. Set the bottom of
each chimney in a glass of water and watch for the results.
You probably have noticed that in a garden which has
just been spaded and raked, the soil under your foot-
steps looks more moist than that in other places. If a
30 AN INTRODUCTION TO AGRICULTURE
soil is well prepared, and shghtly compact, the water
rises readily and much will be lost by evaporation unless
the process of evaporation is checked.
26. Checking Evaporation.— The evaporation can
be checked by loosening the particles of soil near the
surface. This loosening breaks up the tubes, sepa-
yates the particles, and prevents the film water of the
lower particles from pressing too tightly together, or
from coming into too close contact with one another.
In this way, the movement of evaporation is greatly
checked, and this explains why cultivation checks evapo-
ration and helps to keep moisture in the soil.
27. Amount of Water Used by Plants.— The
, mantener ee. | amount of water which
| MoisTuRe REQUIREMENTS OF PLANTS | plants contain, even when
(POUND OF REQUIRES OF WATER ~ :
eae apparently dry, varies
greatly. To keep healthy
and secure enough raw
50 LBS
food material from the
soil, a plant must contin-
uously have a great quan-
tity of water passing
through its stems and
branches to the leaves.
Committee of the National Fertitizer ‘Lhe greater part of this
ete: water, when it has reached
the leaves, evaporates from them into the air. Experi-
ments have shown that, for each pound of dry grain to
be harvested, from three hundred to five hundred pounds
of water pass through the plants producing the grain.
28. Effects of Too Little Water.— When plants
WATER IN THE SOIL 31
do not receive enough water they stop growing, or grow
very little. This is both because water is a raw food
material and because it carries to the leaves the other
raw food materials which the plant gets from the soil.
When a plant does not receive enough water, it partly
closes its breathing pores so that less water evaporates.
But if the amount of water still given off by the leaves
is so much that not enough is left to keep the plant stiff
and rigid, the leaves, and the other green and tender
parts wilt.
A leaf is very much like a little toy balloon; as long
as the balloon contains enough air, it is round and
smooth, but, when it does not contain enough air, it
loses its shape and shrivels. In just the same way, a
leaf stays firm and in shape as long as it contains enough
water, but as soon as it holds too little water, it begins
to wilt and droop.
29. Effects of Too Much Water.— Plants may
suffer from too much water in the soil as well as from
too little. If it rains so hard that water stands for
some time in a cultivated field, where corn, clover, or
erains are growing, you know that the plants will die.
We commonly say they are drowned out. You see, the
soil has become so wet that the water fills all the spaces
among the soil particles, and there is no room for the
air. Good soils must have air in them. The roots of
plants need air and so do the good bacteria which are
needed in the soil.
30. Effects of Water on the Development of
Roots.— The roots of plants will not grow down into
any free water in the soil. When plants find the
32- AN INTRODUCTION TO AGRICULTURE
ground too wet, the roots stop growing down and begin
to spread out near the surface. This develops a shal-
low root system and crowds all the roots near the sur-
face. Later, when the weather gets hot and dry, the
top soil dries out rapidly and the roots being near the
surface, dry up, because they cannot then grow down
quickly enough to reach the moisture deeper in the soil.
It sometimes occurs that when land is tile drained the
crops dry out. In such a case one would naturally con- ©
clude that the tile removed too much water, but this is
generally not so. On the contrary, drying out is due
to the fact that the tile did not remove enough water,
soon enough. Thus a shallow root development oc-
curred. Had the roots gone down deeper earlier in the
season, the crops would not have dried up.
31. Wet Soils are Cold and Sour.— A soil that is
very wet is cold. ‘There are two principal reasons for
this; the warmer air cannot enter the soil, and also,
large amounts of water are evaporating from the sur-
face. Evaporation of a liquid takes away heat. Wet
soils are generally sour or acid because there is little
opportunity for the acid to drain off.
32. The Amount of Water Held by Soils— The
amount of water held by soils depends upon the size of
the soil particles and the amount of humus the soils
contain.
Sandy soils hold about 15 per cent water
Loam cc (79 (<3 95 (74 (<3 “
Clay cc (74 (74 30 (73 (q5 (<4
Marsh “ (74 ce 150 “cc (<3 “cc
WATER IN THE SOIL 33
This means that 100 pounds of an average, air dried,
sandy soil will hold about 15 pounds of water when
water is added to it, and 100 pounds of a loam soil,
about 25 pounds, and so on.
33. How the Soil can be Made to Hold More
Water.— Humus acts like a sponge in holding water.
It not only soaks up water but at the same time covers
itself with water. By soaking up, we here mean that
water enters into the material. ‘The mineral soil par-
ticles take no water into
the inside of themselves.
The water they retain as
we have already seen, is
found only in the form of
EXPERIMENT SHOWING INCREASE OF
SURFACE BY SUBDIVISION
a film on the outer surface
of the soil particles. If
we take a stone one inch in diameter and break it up into
one thousand pieces, and then compare the surface area
of all the pieces with that of the original stone, we shall
find that the sum of the surface area of all these pieces, is
very much larger than that of the original stone. There-
fore the amount of film water held by all the pieces would
be very much greater than that held by the stone. Now
let us take an illustration of this. A cube of cheese one
inch square has an area of six square inches. By three
cuts with a knife, the inch cube can be made into eight
half-inch cubes. The surfaces of these eight cubes to-
gether is now twelve square inches or twice that of the
inch cube. Furthermore, the inch cube offered no space
into which a liquid could be poured, but the eight smaller
cubes thrown together offer many little spaces.
34 AN INTRODUCTION TO AGRICULTURE
34. Humus and Water Holding Capacity.— It
has been estimated (Farmer’s Bulletin 245), that one
ton of humus will absorb two tons of water and give it
up readily to growing crops. This would make its
water capacity 200 per cent. Therefore, we readily con-
clude that as the amount of humus in a soil increases,
the water holding capacity of the soil increases. This
shows us again the great value of manure, straw, sod,
and in fact, all forms of organic matter, in the soil, and
makes us realize why an effort should always be made
to return them to the soil instead of permitting such
materials to decay in piles, or to be- burned, or otherwise
neglected.
35. The Benefits of Underdrainage.— When in
any soil free water is inclined to accumulate near the
surface, so as to interfere with the downward develop-
ment of the roots, drainage is necessary. There are
many reasons why soils often contain too much water.
The land may be too low or too flat. The nature of the
subsoil may be such that it does not allow the free water
to pass away quickly enough. Or there may be too
much seepage from some higher land near by. Under-
drainage is absolutely necessary to remove this excess
of free water. When the free water, which in wet
soils is cold, stale, and foul, and often acid, is carried
off, there will be more room for air in the soil, the roots
will grow deeper, and the soil will be warmer. LEspe-
cially in the spring do we need warm air in the soil to
allow early preparation of the seed bed to hurry the
growth of young plants, and to hasten the making of the
raw plant food they need.
WATER IN THE SOIL 35
36. Methods of Drainage.— There are four com-
mon methods used in draining land: the surface drains,
which are generally open ditches; tile drains; vertical
drains; and dynamiting the subsoil.
Tile Drains.— One of the most satisfactory ways of
draining land is with tile. The tiles are generally one
foot long and vary in diameter, four inches being the
smallest diameter commonly recommended. ‘These tiles
are laid in a ditch which is three or more feet deep, ac-
Guu Wry
Wifi rag N\\ val
Her it AN (\ i WANG) AU pi \\ Nh) a
sty sus yy Nt UNeene \ tra =
~Saees Wa NCCE Nall am i ae
V//
A TILE DRAIN
cording to the soil condition. The tiles are placed end
to end, without cementing, on a uniform grade of two
or more inches per hundred feet, and the trench or ditch
in which they are laid is filled with earth. The free
water from the soil gets into the tiles through the small
spaces where the ends join one another and flows through
the pipes of hollow tiling. The rows of tile are placed
through the field at distances apart varying from three
to eight rods, according to the character of the soil.
They are put closer together in heavy soils than they
are in light. :
Surface Drains.— Farmers sometimes drain their
land by open ditches, but it is hard to work a field cut
36 AN INTRODUCTION TO, AGRICULTURE
up in this way. When it is necessary to have such
ditches, it is best, if possible, to make them so broad
and so gently sloping as to permit them to be planted
to grass and to be mowed readily with a mower.
37. Irrigation.— By irrigation we mean the addi-
tion of water to soil which does not get enough from the
rainfall. Large areas of land, amounting to millions
of acres, which naturally do not receive enough rain-
fall, have by means of irrigation been brought into culti-
vation. Irrigation mostly is confined to arid and semi-
arid regions. On a small scale, it is, however, also
practical in some of our southern states where the sum-
mers tend to be too dry. Some of our richest and most
valuable soils are found in irrigated regions, land which,
without irrigation, would be useless. All our large irri-
gation projects are found in the western states.
38. Sources of Water.— The most common source
of water for irrigation is rivers. These are dammed
quite frequently in a number of places, so as to make
large storage reservoirs which hold back the fall, winter,
and early spring water when it is not needed. From
these reservoirs, canals carry the water to be distributed,
by means of smaller canals, over the land. Generally
the amount of water allowed each farmer in an irrigated
section is limited, and this limit checks all waste and
insures the most economical use. Thus in the height of
the growing season, when much water is needed, it is
available. Small projects often are irrigated by means
of pumps. That is, the water is pumped from a river
or from wells into canals, to be distributed. In like
WATER IN THE SOIL 37
manner artesian wells also are used for irrigation.
Although there are many disadvantages to irrigation,
there is one great advantage and that is that the crops
can be watered when they need the water most. Two
to four irrigations a season are generally enough to pro-
duce most of our common crops.
QUESTIONS AND PROBLEMS
1. If an inch cube were cut into 64 equal cubes, how many
cuts would you have to make, how much surface would be
added by each cut, and how would the final surface compare
with the original surface ?
2. Give illustrations of capillary attraction not mentioned
in the book.
3. Which would be better, to water a lawn or garden a
little and do it often, or give it a thorough soaking once in
a while? Why?
4. Would you pick lettuce early in the morning or in the
middle of the forenoon? Why?
5. Can every piece of land be drained? What conditions
are necessary in order that it may be drained?
6. If the wheat plant uses 450 Ibs. of water to produce one
pound of dry matter, how many tons of water per acre would
be required to produce a crop of 30 bu. of wheat to the acre?
7. If one inch of water over an acre weighs nearly 100
tons, what is the weight of the annual rainfall per acre in
your locality ?
8. Why does draining the soil enable a farmer to work it
earlier in the spring?
9. Why will plants on well drained land stand a drought
better than plants on poorly drained land?
88 AN INTRODUCTION TO AGRICULTURE
Bulletins for Sale by Superintendent of Documents, Wash-
weton, 1. :C.
Studies on Movement of Soil Moisture, Soils Bulletin 38,
10 cents.
Mechanics of Sow Morsture, Soils Bulletin 10, 5 cents.
Moisture Content and Physical Condition of Soils, Soils
Bulletin 50, 15 cents.
Water Requirements of Plants, B. P. I. Bul. 284, 15 cents.
Methods of Applying Water to Crops, Yearbook, Sept., 514, 5
cents.
Agricultural Duty of Water, Bulletin 526, 5 cents.
Farmers’ Bulletins.
Management of Semi-arid Soils to Conserve Moisture, F. B.
266.
Tile Drainage on the Farm, F. B. 524.
Drainage of Farm Lands, F. B., 187.
Practical Information for Beginners in Irrigation, F. B. 864.
Farm Reservoirs, F. B. 828.
Irrigation of Orchards, F. B. 882. ‘
Surface Irrigation for Eastern Farms, F. B. 899.
CHAPTER V
TILLAGE
“Tillage is manure.”
39. The Ideal Condition of the Soil.— If a seed is
to germinate readily it needs air, warmth and moisture ;
and if a plant is to thrive, and have a vigorous root de-
velopment, it needs a mellow, slightly firmed seed bed.
Such a seed bed is in a good physical condition or is in
good tilth. Good tillage, proper drainage, organic mat-
ter, and lime have much to do with the tilth of a soil.
40. Objects of Tillage— The term tillage gener-
ally covers all those operations used in fitting the soil
for the seed, and in caring for the growth of the crop.
The principal reasons for the tillage are: to provide a
good home or growing place for the crop; to conserve
moisture ; to liberate raw food materials; and to destroy
weeds. The better the physical condition, the greater is
the water capacity of any particular soil, the more is
evaporation reduced, and the more satisfactory is the
capillary movement. Earth brought to the surface from
a depth of a few feet is not very productive until it has
been exposed to the weather for some time. Such earth
needs the action of the air, sunlight, etc., to make it
productive. To some extent, the same is true of our
39
40 AN INTRODUCTION TO AGRICULTURE
upper soil in the fields. Weeds must be destroyed
promptly, as they not only occupy space which belongs
to the crop but they also rob the soil of moisture and of
raw food materials which should go to the crop.
41. The Preparation of the Seed Bed.— Plowing.
— Generally the first important work necessary in the
preparation of a good seed-bed is plowing. Thorough
plowing is essential, and if this work is poorly done
the benefits of all the other operations will be greatly
lessened. Good plowing is just as essential as good
soil and good seeds, and unless plowing is done in the
best manner and at the right time, the best results can-
not be obtained. The pride of every plowman is a
straight, well-turned furrow. Its true merit is meas-
ured by its depth, the manner in which it 1s turned, and
the way in which it lies. When properly turned, it
will present a loosely pulverized furrow-slice which
completely covers all the vegetation which was on the
surface. If the land is plowed while it is too wet or
too dry, not only is good plowing impossible, but the
soil even may be ruined for at least a year. When land,
which is not going to be put into crop until the follow-
ing spring, is plowed in the fall, the complete pulverizing
of the furrow-slice is not so important, because the lumps
and clods will crumble and pulverize under the action
of the weather.
Mixing the Soil with Vegetable Matter.— Land which
is heavily manured, or which contains much vegetable
matter, such as a green manure or a sod, is benefited by
being disked before it is plowed, so that the organic
matter may be mixed thoroughly with the soil. In-
TILLAGE 41
jurious effects often result when too much organic mat-
ter, which has not been thoroughly mixed with the soil,
is plowed under. ‘This organic matter is likely to form:
a layer between the furrow-slice and the soil directly
A GANG PLOW.— Courtesy of the Janesville Machine Oo., Janesville, Wis:
beneath it, which may prevent the capillary rise of
water. ‘This fact may be demonstrated easily with the
lamp chimney used in the experiment to illustrate the
rise of water.
Half fill the lamp chimney with fine sand or any dry soil.
Add to this lawn clippings or chopped hay to make a layer:
about an inch thick, and then fill the remaining space in the
chimney with the soil material. Now set the bottom in
water, as you did in experiment before, and note the results.
Disking.— Disking is especially useful in pulverizing
plowed sod land, and in loosening any crusted condition.
of the surface of a field which has lain for some time
after it has been plowed, or on which many small weeds.
42 AN INTRODUCTION TO AGRICULTURE
have started to grow.
NH
a
a
A SOIL FERTILITY BARREL
The water level can rise no higher than the lowest stave. The fertility
of the soil is limited by the lowest amounts of its most indispensable ele-
ments.— From Wisconsin Bulletin 265.
sium; and 50 bushels of oats and 114 tons of oat straw
remove 26.6 lbs. of nitrogen; 6 lbs. of phosphorus, and
67.6 lbs. of potassium. These figures are here given
merely to show that no two crops use the elements of
plant food in similar amounts or in similar proportions.
50. The Use to a Plant-of the Elements of Plant
Food.— Potassium.— Most of the potassium goes into
58 AN INTRODUCTION. TO AGRICULTURE
the straw and stalks of the plants. It strengthens and
stiffens these parts. Weak stalks and weak stems in
common farm crops are an indication that not enough
potassium is available. Besides strengthening and
stiffening plants, an ample supply-of potassium hastens
the maturing of plants.
Phosphorus.—Much of the phosphorus found in
plants is in their seeds. Phosphorus helps to fill out
the seeds and make them plump. Some of the phos-
phorus in the grain is discarded in the bran when
flour is made, and for this reason white flour is not
‘so complete a food for man as whole wheat flour.
Phosphorus also causes plants to ripen more quickly.
When the conditions for plant growth are favorable,
the occurrence of small, shriveled grains is an indi-
cation that there has not been enough available phos-
phorus for the plant.
Nitrogen.— The greater part of the nitrogen is also
found in the seed. An abundant supply of nitrogen
also results in the production of large, healthy leaves
and stalks. Hence nitrogen is especially valuable for
the plants which are raised for their leaves and stems,
such as hay, asparagus, and lettuce. Too much nitro-
gen in a soil tends to retard maturity.
51. Evidence of Lack of Plant Food'— A lack
of any of these elements, potassium, phosphorus, and
nitrogen, will greatly lessen a crop. Whenever a crop
is increased by adding to the soil a material contain-
ing any of these elements in an easily available form,
you may know that the soil itself is failing to furnish
enough of that particular element of plant food.
SOIL FERTILITY ao
52. Fertilizers.— An important question for every
farmer to consider is how he is going to provide the
plant food needed by his growing crops. Often he
has to do this by adding to the soil some substance con-
taining one or more of the three essential elements of
plant food, phosphorus, potassium, and nitrogen.
Any substance so added is called a fertilizer. ‘There
: aaa oF Tilinois Circular 168
LAND TREATED WITH MANURE, LIMESTONE AND A PHOSPHATE FERTILIZER
are two classes of fertilizers, the natural and the arti-
ficial or commercial. Natural fertilizing products
such as manure, weeds, and crop residues like roots,
straw, stalks, and leaves, are examples of natural
fertilizers. Manufactured fertilizing products such
as nitrate of soda and bone meal, which are prepared
and sold in the commercial market, are examples of
commercial fertilizers.
60 AN INTRODUCTION TO AGRICULTURE
53. Manure.— Close at hand for every farmer is
a most valuable source of plant food. Barnyard
manure contains all of the three essential elements of
plant food. The average composition of farm manure
compiled from many analyses is approximately as fol-
lows: Water 75% and organic matter 25%. One ton
of manure will contain on an average 10 lbs. of nitro-
Circular 168
LAND TREATED WITH MANURE ONLY
University of Illinoi:
gen, 3 lbs. of phosphorus, 8 lbs. of potassium, and about
500 lbs. of organic matter. The remainder will be
mostly water. This analysis, however, will vary
greatly according to the kind of animals from which
the manure comes, the amount and kind of bedding
used, the feed fed to the animals, and the manner in
which the manure has been kept. Much of the value
is often wasted by the slipshod way in which many
SOIL FERTILITY 61
farmers take care of the manure. Manure which has
been ‘“ fired ” or been exposed to rain has lost much of
its raw food materials. To preserve its full value,
manure should be kept moist and compact, or else it
should immediately be spread upon the land.
Value of Manure If the same amounts of raw
plant food which are found in a ton of average farm
manure were purchased in the form of commercial
fertilizers, they would cost between two and three dol-
lars. The organic matter which manure adds to a
soil also has a little value which is not figured in the
estimate just given. For in addition to the elements
of plant food and the organic matter, manure contains
enormous numbers of beneficial bacteria.
Manure Contains Inttle Phosphorus.— In spite of
all its good ingredients manure is, however, very low
in phosphorus. You can see this from the analysis
already given. In most of our soils, too, phosphorus
is the element of plant food most lacking. For these
two reasons it is becoming a wise farm practice to add
to manure, or to reinforce it, with some phosphorus
fertilizer. Raw phosphate rock, very finely ground,
is being widely used to reinforce manure and often used
as an absorbent in the barn.
Amounts of Manure to Apply.— It is estimated that
ten tons of manure applied to an acre of land once
every four or five years is a fair application of manure
for ordinary farming. It is not unusual, however, for
a truck farmer to apply as much as twenty tons to
one acre in one year. It has been repeatedly proven
that manure put on the soil evenly and rather lightly
62 AN INTRODUCTION TO AGRICULTURE
over a large area will give larger returns than manure
applied irregularly and heavily over a small area.
This is why a manure spreader should be used on all
farms which have enough stock to justify the farmer
in buying one.
If a farmer adds to his land ten tons of average
manure per acre once in four years, he will be adding
about 100 lbs., of nitrogen, 30 lbs. of phosphorus, and
80 lbs. of potassium. The question he should then ask
himself is: Will this be sufficient to replenish the
amount of these three elements removed by four years
of cropping? It is safe to say that proper calculations
on his part will show that there is much more raw
plant food removed from the soil than there is returned
to it. He now faces a new and serious problem,
namely, how long with such a system of farm practice
will his soil continue to be productive. This will de-
pend on the amount of plant food in the soil. If our
land is to remain productive, farmers everywhere
must face and work out these problems. In making
calculations like the one just suggested, it is customary
to omit the amount of nitrogen removed by a legume
such as clover, because the nitrogen which such a crop
contains is said to come from the air.
Care of Manure.— The best method of handling
manure is to haul it to the field day by day, as it is
made. Unless manure is kept moist and compact and
is preserved in such a manner that the liquid part of
it cannot be washed away by rains, much of its value
will be lost. Manure should never be allowed to lie
exposed in piles for very long periods. All records
SOIL FERTILITY 63
show that it loses in weight and in value rapidly if
allowed to accumulate in large piles. Knowing how to
properly care for manure and how to get the most value
out of it is indeed an art for a farmer.
54. Crop Residues.— Whenever crop residues, such
as stubble, corn stalks, sod, ete., are plowed into the soil,
they decay rapidly and leave the elements of plant
food in such a form that these elements become easily
available for the succeeding crops. The roots of deep-
rooted plants add considerable plant food to the surface
soil, and thus some plant food, which ordinarily would
be out of the reach of the roots of shallow-rooted crops,
is put where these shallow roots can get it. Every one
knows that a crop which follows clover, alfalfa, or some
other legume is usually better than it is when the same
crop follows a non-legume, such as corn or wheat. This
improvement is partly due to the fact that stubble and
roots of legumes contain more nitrogen than do the
roots of non-legumes, and partly, also, to the fact that
these legume residues decompose more readily and
liberate the plant food more quickly than do the residues
of non-legumes.
55. Commercial Fertilizers.— Commercial fertiliz-
ers are materials, prepared and sold in the market,
containing nitrogen, phosphorus, and potassium, in a
form suitable for use. These fertilizers are commonly
sold by the ton in two hundred pound sacks. Many
of them look like a coarse powder much like wood
ashes. Others are much like salt in texture but are
never as white and clean as salt.
If the school has samples of any commercial fertilizers
64 AN INTRODUCTION TO AGRICULTURE
make a study of them. Note their color, texture, solu-
bility in water and their reaction with litmus paper.
The value of any commercial fertilizer depends upon
the amount and the solubility of the three essential
elements it contains.
The price of com-
@ mercial fertilizers
varies greatly. Dur-
No. 6019
JOHN DOE & COMPANY, ing the European
of Columbus, Ohio, War the value of
Guarantee this
SNOWFLAKE FERTILIZER
nitrogen and potas-
to contain not less than sium became so high
2.4 per cent. of total nitrogen, (N), . that it almost pro-
10.0 per cent. of potash, (K2O), soluble in ;
water, hibited the use of
8.0 per cent. of soluble and reverted
phosphoric acid, (P:Os), and these elements for
1.0 per cent. of insoluble phosphoric acid, -
(P20:). agricultural — pur-
Purdue University YA 5 om pb poses. Ordinarily
Experiment Station, 5 /
LaFayctte, Indiana. Pit 18 eents per pound
State Cnemist. . .
is the average price
of nitrogen in com-
Purdue University Agricultural Experiment
Station Bulletin 199
mercial fertilizers,
that of phosphorus 8 cents and potassium 6 cents
per pound, depending upon the materials from which
they are made.