91
63

‘“ QUESTION SUMMARY

TO ACCOM PANY
“SOIL FERTILITY’AND PERMANENT
AGRICULTURE”

BY

CYRIL G. HOPKINS, Pu.D.

PROFESSOR OF AGRONOMY IN THE UNIVERSITY OF ILLINOIS
CHIEF IN AGRONOMY AND CHEMISTRY AND VICE
DIRECTOR OF THE ILLINOIS AGRICUL—

TURAL EXPERIMENT STATION

GINN AND COMPANY

BOSTON - NEW YORK : CHICAGO - LONDON

COPYRIGHT, 1912, BY GINN AND COMPANY

QUESTION SUMMARY

TO, ACCOMPANY

“SOILAEERTILITY AND PERMANENT
AGRICUL F URE”

BY

CMRI Ge) PhO RIUN SS: Baek),

PROFESSOR OF AGRONOMY IN THE UNIVERSITY OF ILLINOIS
CHIEF IN AGRONOMY AND CHEMISTRY AND VICE
DIRECTOR OF THE ILLINOIS AGRICUL—

TURAL EXPERIMENT STATION

GINN AND COMPANY

BOSTON - NEW YORK - CHICAGO - LONDON

COPYRIGHT, 1912, BY GINN AND COMPANY

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PREEAT ORY. NGPEE

While the author recognizes that there is at least as much of
mental culture in a study of plant-food compounds and of the
bacteria of clover roots as there is in a study of Latin com-

pounds and Greek roots, he also realizes that a course in soil

fertility should do more than develop the mind. If there is any
place for the ‘“ educated” man who is graduated with largely
increased mental power but with little positive addition to his
own knowledge of facts and principles, that place is not in agri-
culture. The educated farmer should have ready for his own use
and defense some actual data supporting and establishing the
most fundamental facts and principles upon which permanent
agriculture must be based. It is worth many times the effort,
for example, to memorize some half-century averages given to
us by those noble men, Lawes and Gilbert, of Rothamsted.
The following list of questions should help the student to
understand what is important to know, and how to study with
effectiveness and with economy of time and mental energy. The
teacher may direct the class to check off certain questions which
he feels are of too little importance or too difficult for the par-
ticular class or for the time that can be devoted to this course of
study ; and it is expected, of course, that additional questions
will be asked, especially such as have large local interest which
may be discussed in lectures embodying material supplementary
to that contained in the text. (The local State Experiment
Station bulletins should be of much value in this connection.)
Many of the questions may be assigned as subjects for written

articles, for the preparation of which the student should be
812.3 iii

iv QUESTION SUMMARY

allowed a week or more, and often required to do some supple-
mentary reading; but the most important and most carefully
written paper required of the student should be in the nature
of a definite plan and rather complete specifications or directions
for the future management of his own farm in a system of truly
permanent agriculture. The analysis of soil, made by himself
if possible (in an accompanying laboratory course in soil fertility),
should serve as a substantial basis for intelligent thinking, and
it is highly desirable that he base his final plans upon such
crop yields as he feels he has reason to assume can and will be
produced.

While some may plan to operate a grain farm and others a
live-stock farm, the average student will probably plan a system
of mixed husbandry, selling the more valuable grains, and pos-
sibly hay too, when worth as much or more than grain, pound
for pound (as with corn at 50 cents a bushel and hay at $18
per ton), feeding the less valuable grain and forage, and saving
labor by allowing live stock to gather the pasture crops and to
return the resulting manures directly to the land. Aside from
computing the amounts of fertility removed and returned to the
soil, he should state the forms of plant food to be purchased,
the rotation of crops, the substitute crops to be used in case of
any crop failure, the rations to be fed (based upon his animal-
husbandry: courses), the farm equipment, and probable labor
required. Finally, he should assume reasonable prices and costs,
and make as safe an estimate as possible upon the financial
outcome.

In the author’s experience this is the most interesting and
valuable work performed by his students, for it enables them
to make definite plans to fit the principles of science into a
knowledge of the actual practice of agriculture on a farm which
is different, perhaps, in some respects, from any other farm.

CYRIL G. HOPKINS
UNIVERSITY OF ILLINOIS

OUESTION SUMMARY

“SOIL FERTILITY AND PERMANENT
eo (Cone (GON Bg MN Oa ia See

CHAPTER I

1. Define science, element, atom, atomic weight, symbol.

2. Define valence, compound, molecule, formula, chemical
action.

3. State the law of constant proportions.

4. Discuss briefly the number and relative abundance of
known elements.

CEA PAE Re: Eh

5. Name fourteen common elements and give the symbol,
atomic weight, and valence of each.

6. Name the eight abundant elements in the earth’s crust
and state the approximate percentage of each. (47, 28, 8, 44,
eeaand three 24.)

7. Give the exact percentages of potassium, phosphorus, and
sulfur reported for the earth’s crust.

8. Name five important elements in the ocean and give the
percentages of potassium and of sodium chlorid.

9. Name the four elements of the air and state the per-
centage of each.

10. Name the elements known to be essential for plant
growth and give percentages of the three that are most abun-
dant in corn.

2 QUESTION SUMMARY

11. Name six acid-forming elements and six base-forming
elements; give formulas for common acids and alkalis, and
equations representing the formation of six salts containing
these twelve elements.

12. What element is contained in all acids?

13. Explain and illustrate acid salts, and monobasic, dibasic,
and tribasic acids.

CHAPTER’ Ii

14. Discuss photosynthesis and condensation in the forma-
tion of sugars, starch, and fiber.

15. Explain the carbon-oxygen cycle.

16. Give names and formulas for five fatty acids and two fats.

17. Discuss the relative abundance of atmospheric carbon
and nitrogen for plant growth.

18. Give chemical names, formulas, and natural occurrence
of oxalic acid, asparagin, and two intermediate products.

19. Give names and occurrence of two proteids and discuss
their composition and possible way of formation.

20. Give formula and occurrence of allyl sulfid.

21. Discuss occurrence and composition of nuclein.

22. Name the elements known to exist as part of the plant
structure or living tissue, and discuss the possible uses of the
other elements essential for plant growth.

23. Explain possible common functions of elements.

24, Explain and illustrate the difference between requirement
and toleration of elements by plants.

CHAPTER VY

25. Name the controlling element in organic compounds and
the corresponding element in the abundant mineral compounds.

26. Name two common rocks of the earth’s crust and dis-
cuss their formation.

27. Name four important rock minerals and discuss their
composition.

SOIL FERTILITY 3

28. Give names and formulas of three silicon compounds of
natural occurrence.

29. Discuss composition and properties of zeolites, sand,
clay, and quartz.

30. Discuss carbonates and give formulas of calcite, mag-
nesite (MgCO,), and dolomite.

31. Discuss losses of rock constituents by weathering and
leaching.

32. Give names and formulas of compounds of phosphorus
and sulfur found in extensive natural deposits.

CHAP EIR WV

33. Define loess, glacial drift, alluvial soil, residual soil, and
cumulose soil (see also page 75).

CHARTER. VI

34. Discuss the operation of natural laws with respect to soil
enrichment and depletion on levei uplands in humid climates.

35. Explain the benefits of soil erosion.

36. State the number of pounds of nitrogen, phosphorus, and
potassium required (1) for the grain, and (2) for the straw or
stover, for a 50-bushel crop of wheat, for roo-bushel crops of
corn and oats, and for 4 bushels of seed and 4 tons of clover;
also the magnesium and calcium required for the 4 tons of clover,
and the total for the four crops of each of seven elements (see
also pages 75 and 154).

37. State the potassium content of the common prairie soil
(surface) of the lower Illinoisan, middle Illinoisan, early Wisconsin,
and late Wisconsin glaciations, and of west-central Minnesota ;
and give reason for differences.

38. Discuss the nitrogen content of the common upland soils
of the southern, northern, and western states, and give reasons
for regional differences.

4 QUESTION SUMMARY

39. Explain the presence of carbonates and of acidity with
reference to climate and to age of soil.

40. State the phosphorus content of the black cotton soil of
India, black earth soil of Russia (Von Ugrimov’s report), of soil
from Turkey in Asia (Massachusetts report), of Bavarian barrens,
of Holland alluvium, of Blue-Grass surface soil and lower subsoil
at the Kentucky Experiment Station, of New Mexican adobe
soil, of Red River Valley soil, and of Illinois deep loess subsoil.

41. State the number of pounds of nitrogen, phosphorus, and
potassium in 2 million pounds of surface soil at Rothamsted,
England, at State College, Pennsylvania, at Wooster, Ohio, at
Urbana, Illinois, and at Columbia, Missouri.

42. Give approximately the average composition of the princi-
pal type of soil in each of five great soil areas in this state.
(The teacher should furnish data in lectures to supplement the
text where necessary and locally possible. )

43. State approximately the average composition of Florida
sand, of Wisconsin residual sand, of Illinois glacial sand, of
Illinois black clay loam (early Wisconsin glaciation), and of
deep peat soil (see also page 498).

CHAPTER Ul

44. Describe Kossowitsch’s experiment to ascertain if the
presence of living plant roots influences the availability of
plant food.

CHAP Bika Vid

45. Name and locate (by map drawing) the fourteen soil
provinces of the United States.

CHAPTER * 1X

46. Describe the location, topography, history, composition,
productive power, and agricultural value of the ‘‘ Leonardtown
loam” and the “ Marshall black clay loam.”

SOr BERTIE Y 5

47. The total phosphorus and calcium in 2 million pounds
of the surface soil of the “ Leonardtown loam” would provide
for how many 4-ton crops of clover ?

48. Describe King’s investigation to ascertain the plant food
made available in poor and good soils.

CHARTER, 2€

49. State the number of pounds of nitrogen and phosphorus
in 100 bushels of ear corn, in 2 bales of cotton lint, in 1000
pounds of fat cattle, in 10,000 pounds of milk, in 500 pounds
of butter.

CHAP TERS xt

50. State the number of pounds of nitrogen, phosphorus, and
potassium in 1 ton of average fresh manure, of average barn-
yard manure, of corn stover, of oat straw, and of wheat straw.

51. State the amount of nitrogen per ton in each of three
nitrogen fertilizers, giving name of each.

52. Name three bone fertilizers and state the average amount
of nitrogen and phosphorus per ton of each.

53. Give the amount and average market value of the phos-
phorus ina ton of steamed bone meal, raw rock phosphate, acid
phosphate, double superphosphate, and basic slag phosphate.

54. Name three potassium salts used as fertilizers and state
the number of pounds of potassium per ton of each.

55. State the amounts of three important constituents in a
ton of average wood ashes.

56. How many pounds of nitrogen, “ available’ phosphorus,
insoluble phosphorus, and of potassium are contained in a ton
of average “complete ”’ fertilizer ?

57. What yield of corn is provided for by 200 pounds per
acre of average “complete”? fertilizer: (1) with respect to
nitrogen? (2) phosphorus? (3) potassium ?

6 QUESTION SUMMARY

CHAPTERS xtt

58. Name the three materials that must be applied to normal
soils to provide systems of permanent agriculture (see page 159).

59. In maintaining fertility without the purchase of potassium,
how many years might be allowed for the removal by erosion of
tr inch of common corn-belt prairie soil from which one third
of its potassium had been removed by cropping and leaching,
if 50 bushels of wheat per acre were sold annually from the
farm ? (See also page 561.)

60. In power to correct soil acidity 1 ton of common lime-
stone is equivalent to how many pounds of quicklime, of hydrated
lime, of dolomitic limestone, of thoroughly air-slacked lime, purity
being assumed ?

61. Describe the Pennsylvania experiments with caustic lime
and ground limestone, and give figures to show their comparative
effect upon crop yields, soil nitrogen, and organic matter.

62. Describe the Maryland experiments with carbonate and
caustic lime.

63. At what rate and frequency should limestone be applied
per acre in humid sections in order to insure its maintenance?
(See also page 561.)

64. Give a reason for testing the subsoil for acidity and
evidence indicating that soil acidity is due in part to inorganic
acid salts.

65. Why should limestone and phosphate not be applied in
intimate contact ?

66. Discuss the degree of fineness desirable for limestone to
be used in soil improvement in humid sections.

CHAPTER iit

67. Name the three great natural sources of phosphorus.
68. As an average what proportion of the phosphorus re-
quired for grain crops is retained in the straw and stover,

SOIL FERTILITY 7

and what proportion is possibly recoverable in the manures in
average live-stock farming?

69. Explain the manufacture of acid phosphate and double
superphosphate. Show reactions and state the percentage of
phosphorus in each, if made from pure materials.

CHAPTER Sly.

70. Discuss active and inactive organic matter and define
humus.

71. Explain ammonification and nitrification, and name three
important requirements in the process.

72. Name three decomposition products of organic matter
which may aid in liberating plant food from insoluble minerals,
and express a quantitative comparison with respect to nitrogen
and phosphorus.

73. Name three practical methods of supplying organic matter.

74. Describe the experiments in Maryland and Canada on
losses of organic matter by exposing manure.

75. As an average what proportion of the organic matter and
nitrogen in feed is possibly recoverable in the manure in live-
stock farming ?

76. Describe the Cambridge experiments with losses of plant
food from manure and from oil-cake fed.

77. Explain parasitism, symbiosis, nitrogen fixation.

78. Discuss the relative abundance, in existing suitable form,
of oxygen and nitrogen for the production of legume plants
properly infected.

79. Explain the need and most practical method of inoculation.

80. On soils of moderate productivity, about what proportion
of the nitrogen for well-infected legume plants is secured from
the soil? Give basis for opinion.

81. About what proportion of the total nitrogen in the plant
is contained in the roots and stubble of red clover? of cowpeas?

8 QUESTION SUMMARY

82. Discuss the Illinois investigation with sweet clover, and
express its manurial value per acre in terms of farm manure.
83. Discuss nitrogen fixation by nonsymbiotic bacteria.

CHAPTER jay

84. Plana practical system of grain farming which shall main-
tain soil fertility without the purchase of nitrogen in any form,
giving figures (on assumed yields) for organic matter and fertility
elements removed and supplied per acre for one rotation period.

CHARTER pov

85. Plan a practical system of live-stock farming which shall
maintain the fertility of the soil without the purchase of nitrogen
in any form, giving figures (on assumed yields) for organic matter
and fertility elements removed and supplied per acre for one
rotation period.

CRAP agi Rs ov eul

86. Name four neutral insoluble phosphorus fertilizers of
animal origin, seven insoluble mineral phosphates, one insoluble
alkaline phosphate, and four soluble phosphorus fertilizers of
acid reaction.

87. Discuss the use of phosphatic marl as a source of phos-
phorus for crops.

88. Name three important points to be kept in mind
when trying to determine fertilizer requirements from culture
experiments.

89. Describe the Ohio manure-phosphate experiments, giving
exact figures to show comparative returns from raw phosphate
and acid phosphate.

90. Describe the Maryland experiments with different forms
of phosphorus, giving some specific information as to results.

91. Describe the Pennsylvania experiments with different
forms of phosphorus, and give some specific data as to results.

SOIL EERTILIZCY 9

92. Give some definite information as to the results of the
Rhode Island experiments with different phosphates.

93. Summarize the results of the Maine and Massachusetts
experiments with different phosphates.

94. Discuss the Indiana and Illinois experiments with
phosphorus.

95. Discuss briefly the report of the National Fertilizer
Association on “‘ Raw Rock Phosphate.”

CHAP PE RA x VIbE

96. Describe Van Helmont’s experiment and state Bradley’s
opinion concerning the food of plants.

97. Discuss Jethro Tull’s plant-food theories, and also state
the views of Thaer and Hunter.

98. Name the discoveries of Priestly, Sénébier, and De
Saussure.

99. Name the important truth established by Lawes and
Gilbert, and the late discovery by Hellriegel, relating to
nitrogen.

100. Discuss Liebig’s views as to the principal source of
nitrogen for plants; also state how many pounds of nitrogen
are contained in normal rainfall per acre per annum.

101. Describe Decandolle’s theory as to the need and value
or reason for crop rotation.

102. Describe and discuss briefly the soil-fertility theories of
Whitney and Cameron, especially with reference to the law of
solution, the rise of plant food from the lower subsoil, and the
effect of manures and fertilizers on crop yields (see also
page 366).

103. Give some facts and figures concerning the early and
continued use of phosphorus in European countries, and estimate
the amount of phosphorus applied in 20 loads of bones of 40
bushels each (see also page 636).

IO QUESTION SUMMARY

104. Give some reasons for changes in crop yields in western
Europe during the last century.

105. Contrast the agricultural conditions and practices of the
Aryan race in Russia and India with those of the Mongolian
race in China and Japan (see also page 594).

CHAPTER XIX

106. Discuss the origin and conduct of the Rothamsted
Experiment Station, name the principal field experiments, and
state the duration of each.

107. Give some definite figures from Agdell field showing the
effect on crop yields of long-continued cropping without fertilizing.

108. At prices given on page 359, state exactly the cost and
value of the increase produced per acre by phosphorus in 36
years in the legume system with the turnips fed on Agdell field.
(Problem to be assigned in advance and answer memorized.
See notes on pages 346, 354.)

109. Give the treatment and average yields on plots 2, 3, aa
8 on Broadbalk field.

110. Discuss the effect of successive increments of nitrogen
on the yield of wheat on Broadbalk field.

111. Give in round numbers the average annual rainfall at
Rothamsted, and in northern and southern Illinois, in Tennessee,
and in this state. (Teacher to supply data in class.)

112. Give the treatment and average yields of barley for
three plots on Hoos field (e.g. O1, A 4, N 2).

113. Compare the durability in the soil of farm manure,
soluble nitrogen, and minerals applied.

114. Give the treatment and average yields of potatoes for
four plots on Hoos (e.g. 1, 2, 8, 9).

115. Discuss the use of acid phosphate as a top-dressing for
permanent grass lands.

116. Give the treatment and approximate average yields of
hay for five plots on The Park at Rothamsted (e.g. 3, 5,7, 9, 11).

SOIL FERTILITY II

117. Compare the effect of salts containing potassium with
that of other alkali salts on the yield of wheat, barley, and hay
at Rothamsted. (Memorize differences between average yields
of plots 12 and 13 on Broadbalk, A 4 and N 2 on Hoos, and
note 4-2, 10, and 9 on The Park.)

118. Discuss the apparent influence of potassium on the bo-
tanical composition of the herbage on The Park, and the resulting
effect on total yield. (Compare plots 7 and 8 with g and tro.)

119. In what different ways may alkali ‘salts bring about
increases in crop yields? (Note the effect of phosphorus on
Agdell clover in 1874 and 1882 and compare with results from
plots 3 and 12, 4-1 and 7 on The Park.)

120. Discuss the effect of enriching the surface upon the
plant food removed from the subsurface and subsoil. (Com-
pare plots 3, 4, and 5 with 7, 12, 13, and 14, page 411.)

121. Discuss the relation between the yields of crops and
their content of phosphorus and of potassium. (Compare plots
4-1 and 7, plots 4-2 and 9, etc., page 418.)

CHAPTER XX

122. Describe the Pennsylvania field experiments with ferti-
lizers, and state briefly the effect of nitrogen, phosphorus, and
potassium, singly and combined.

123. Give figures from the Pennsylvania experiments to show
the effect upon productivity of crop rotation without fertilization.

124. Explain why it is practically impossible to completely
exhaust the fertility of any soil.

125. Explain how apparent increase from long-continued soil
treatment in comparison with no treatment may really represent
no increase in productivity.

126. Discuss the variation due to soils and crops in the agri-
cultural value of a ton of manure.

127. Discuss the Pennsylvania experiments with reference
to the maintenance of soil nitrogen.

12 QUESTION SUMMARY

128. In permanent agriculture should the apparent increase

from the return of plant food needed to maintain initial produc- -

tivity have any place in the computed profits ?

CELA PAN: exe

129. Discuss (1) the common effects of a good rotation in
comparison with no rotation or with a poor rotation previously
practiced ; and (2) the probable relation of crop yields during the
second or third rotation period in comparison with the first and
with the subsequent periods.

130. Describe the Ohio experiments with various fertilizers
at Wooster and Strongsville.

131. Summarize the results of the Ohio experiments with
special reference to the need and effect of nitrogen, phosphorus,

°

and potassium.

132. State the return per dollar invested in phosphorus when
applied in addition to nitrogen and potassium in the five-year
rotation at Wooster and Strongsville, and suggest a practical
method of utilizing this knowledge. (Problem to be assigned in
advance and answers memorized. )

133. State the essential facts secured in the Ohio experi-
ments with bone meals in comparison with factory-mixed “ com-
plete” fertilizers.

CHAPTER oer

134. Four-ton crops of clover (or go-bushel crops of corn)
per acre each year since Columbus discovered America would
have required the total phosphorus to about what depth in the
common Illinois corn-belt prairie soil ?

135. Describe the Illinois field experiments at Urbana, and
give some definite figures showing the effect of rotation and of
soil treatment upon the yield of corn.

136. What important facts are emphasized by the results from
the Illinois experiments at Sibley?

SOIL PER TIEILY 13

137, Summarize the ten years’ results from the Illinois experi-
ments at Bloomington.

138. Compare rock phosphate and feldspar or granite with
reference to their use in soil enrichment.

139. Describe the Illinois experiments on sand soil at Green
Valley, giving some figures to show the most important results.

140. Describe the Illinois experiments on peaty swamp land
at Manito, and discuss the effects of limestone, phosphorus,
potassium, sodium, land-plaster, and manure.

141. Discuss peaty alkali soils. (Alkali soils in humid sections
are formed by the evaporation from exposed land surface of
drainage or seepage waters, as from old swamps or along
their borders.)

CHARTER: Soci

142. Give figures showing the effect of green manure, lime-
stone, and phosphorus on wheat on the Illinois experiment field
at Odin.

143. Give data from the Illinois experiments at Fairfield
bearing upon the use of potassium.

144. If 50 bushels of wheat per acre were sold annually from
the common prairie land of southern Illinois, how many years
would be required to thus take from the farm as much potassium
as is contained in 2 million pounds of the surface soil?

145. Suggest practical treatment for the loess-covered hill
lands of the South Central states, citing results of experiments to’
support the suggestions.

146. Why is the application of phosphorus usually less impor-
tant on sloping uplands than on those of more nearly level
topography ?

147. Compare the general results of field experiments reported
from southern Iowa and from northern Mississippi.

148. What general conclusions are indicated by the Georgia
and Alabama experiments with fertilizers for corn and cotton?

14 QUESTION SUMMARY

149. Describe the Louisiana experiments at Calhoun and
give figures summarizing the average results secured.

150. Compare the values per acre of corn and cotton and
the draft upon the stock of fertility when corn and cotton lint
are sold.

CHAPTER Ay,

151. Discuss the Minnesota experiments with reference to
the maintenance of nitrogen.

CHA PIPER, XOavi

152. Describe and summarize the Canadian field experiments,
especially with reference to fresh and rotted manure and differ-
ent forms of phosphorus.

CHAPTER] DOC vV

153. Discuss the value of the short-time culture methods of
Whitney and Cameron in comparison with long-continued field
experiments for determining fertilizer requirements.

CHAPTER, Xv i

154. Give the average composition and discuss the cost and
use of common “ complete ” commercial fertilizers.

155. What percentage increase in crop yield might reasonably
be expected from the nitrogen and “ humus effect’ of 50 pounds
of dried peat soil applied as a filler in 200 pounds of “ com-
plete ” fertilizer (1) on the brown silt loam of the corn belt, and
(2) on the soil at Wooster, Ohio? (In humus the ratio of nitro-
gen to carbon approaches 1 to ro, and the ratio of carbon to
organic matter is nearly 1 to 2.)

156. Name four forms of commercial nitrogen and give
examples and pounds of nitrogen per ton of each.

157. Describe two commercial processes for the artificial
fixation of atmospheric nitrogen.

SOM VPERTILITY 15

158. Name three different sources of commercial potassium
and three commercial products from the present most important
source, giving pounds of potassium per ton of each.

CHAPTER, 2Oov Til

159. Discuss crop stimulants and protective agents, giving
illustrations.

CHAB TER: ox 1s

160. Mention some critical periods in plant life and explain
the possibility of exaggerated effects from materials applied as
plant food.

CHAPTER XXX

161. Name four factors governing the composition of manure.

162. State the number of pounds of nitrogen, phosphorus,
potassium, and organic matter in r ton (1) of average fresh
stable manure, (2) of average rotted yard manure.

163. How much manure containing 85 per cent of moisture
is equivalent to 4 tons of the same kind of manure containing
624 per cent of moisture ?

164. About how would it affect the composition of a ton of
average fresh manure to replace the urine with rain water ?

165. Name four factors influencing the agricultural value of
average or “‘standard”’ manure.

166. Give data from field experiments showing some actual
variations secured in the agricultural value of manure.

167. Discuss the use of materials for preserving or increasing
the value of manure, and cite some definite results secured.

168. Give data showing losses from exposure of manure.

CHAP THR: XOX XT

169. Discuss briefly the removal of plant food from plants
exposed to the weather. :

16 QUESTION SUMMARY

CHAPTERY XXOxaT

170. Name four ways in which plant food may be lost or
removed from the soil.

171. State about the average amounts of phosphorus, potas-
sium, magnesium, and calcium lost per year in drainage water
from an acre of normal land in humid sections.

172. Discuss the Rothamsted investigations showing loss of
nitrogen by leaching, and give method of prevention and data to
prove its effectiveness.

173. Discuss loss of nitrogen from soils as reported from the
Minnesota and Canadian investigations.

174, Explain how erosion may contribute toward the main-
tenance of mineral plant food in the surface soil.

175. Where the upland surface soils are poor in minerals and
nitrogen compare the probable effects of gullying and sheet
washing from the hills upon the fertility content of the over-
flowed bottom land.

176. Suggest methods for preventing the loss of plant food
caused by erosion.

CHAPTER. XXX

177. Explain the fixation of bases and phosphorus' in soils,
giving possible reactions, and state how nitrate nitrogen may be
fixed in the soil.

CHAPTER: XXXTV

178. Describe practical qualitative tests for soil acidity and
for limestone in the soil.

179. Name suitable materials in which to supply nitrogen and
phosphorus in fertilizer experiments; also name objectionable ma-
terials for nitrogen, phosphorus, and potassium, and give reasons.

180. If the soil is deficient in calcium or magnesium capable
of ready liberation for plant food, in what form could they be
economically applied ?

SOLE BE RVILITY ET,

CHAPTER. XX V

181. What element or elements are likely to be deficient or
abundant (1) in peat soils? (2) in “clay” soils? (3) in residual
sand soils? (4) in glacial sand soils? (5) in limestone soils?

CHAP TEREX XXavVi

182. Name the six essential positive factors in crop produc-
tion, and mention one example of possible improvement for
each factor.

183. Discuss briefly the rainfall records of North Platte,
Nebraska, as representative of the semiarid region. (Late
records show 22.41 inches for 1909, and ro.70 for 1g10, which
is the lowest record in 36 years, averaging 18.63 inches, with
19.14 for 1875-1892, and 18.12 for 1893-1910. By nine-year
periods the averages are 19.95, 18.33, 14.54, and 21.70, with
23.07 as the average for the eight years ending 1909, or almost
60 per cent above the previous nine-year average. )

184. Compare roughly (by map drawing) the humid and
semiarid regions of the United States, receiving more and less,
respectively, than 20 inches as the average annual rainfall.

185. Compare the total area of farm land in the United States
(873,729,000 acres, United States Census of 1910) with the
area possible to be added by irrigation and drainage. (The
United States Department of Agriculture estimates the total
area of land capable of cultivation at 950,000,000 acres.)

CHAP TERS XXOCViE

186. If $2 per acre yearly invested in soil improvement would
increase the crop yields by the equivalent of 2 bushels of corn
per acre each year above the preceding year, what would be the
cost per bushel for the increase in the fifteenth year?

18 QUESTION SUMMARY

CHAPTER XXXVIII

187. If it costs $4 an acre to grow corn and 5 cents a bushel
to harvest and market the crop, with interest at 5 per cent, taxes
at .5 per cent, and corn at 4o cents a bushel, what is land
apparently worth that will produce 20 bushels of corn per acre?
40 bushels? 80 bushels? roo bushels? At what yield does the
land become valueless? What other necessary item of expense
should be included to protect capital invested in land, and what
are some of the results in the United States from neglecting
this item?

CHA PACER EXexie

188. Summarize the history, rules, and ultimate results of the
agricultural teaching and practice of the ancient Mediterranean
countries (see also page 302).

APPENDIX

SECTION I

189. Name four Western and three Eastern states in which
extensive high-grade phosphate deposits are known to exist.
(Montana is now in this list; and some high-grade rock has
been found near Midway, Kentucky, for which point some soil
analyses are given on page 65. A United States Geological
Survey press bulletin, released for publication on November 10,
Ig1i, states that the work of the Geological Survey shows
approximately 2} billion long tons of phosphate averaging
14 per cent phosphorus, corresponding to 70 per cent of tri-
calcium phosphate, in the Western states. The bulletin adds:
“Nor does this include the tonnage of the Montana phosphate
withdrawals, which aggregate nearly 34,000 acres.”

190. Discuss the domestic supplies, consumption, and exporta-
tion of natural phosphates.

191. Discuss the source and consumption of phosphate in
other countries.

SEC LION tt

192. Discuss the advantages and disadvantages of using the
element system of nomenclature for reporting analyses of soils
and fertilizers.

SECTION. III

193. Compare the composition of unleached wood ashes and
soft coal, also of wheat flour and wheat bran, as foods for
growing animals (domestic or human).

32)

20 QUESTION SUMMARY

SECTION fv:

194. Compare the average estimated production, price, expor-
tation, and apparent percentage increase in domestic consump-
tion of corn and wheat for 1896-1900 and 1906-1910 with the
percentage increase in population for the same decade. (See note, _
page 617. The Illinois corn acreage is reported for 1899 and
1909, respectively, as 10,266,335 and 10,045,837 by the
United States Census; as 6,941,548 and 7,288,563 by the
Illinois State Board of Agriculture; and as 6,865,287 and
10,300,000 by the United States Department of Agriculture.)

195. Give the increase or decrease in yield per acre by
twenty-year averages (1866-1885 and 1886-1905) for corn
and wheat in the United States; also compare the total pro-
duction of wheat in the Dakotas with that of all states east of the
Mississippi (excepting Indiana and Illinois) for the year 1909.

196. Compare the ten-year average yields of wheat of Russia,
the United States, this State, Germany, United Kingdom, and
Denmark, and give your opinion as to the causes for the
greater yields in western Europe.

197. Compare the phosphorus content of the phosphate ex-
ports with that of the wheat produced in the United States.

198. Compare the plant-food content of the wheat crop and
of the butter exports of Denmark with that of the foodstuffs
imported into that country. (Denmark imports about as much
barley as corn, and about as much mill products as oil cake.)

SECTIGN: ¥.

199. Name the determinations that should be made in ana-
lyzing a soil from the humid section, in order to secure definite
information upon which to base plans for a practical system of
permanent agriculture.

200. What is the significance in soil analysis of dry matter,
of organic carbon, of total calcium, of calcium carbonate equiva-
lent to carbonate carbon, of calcium carbonate required ?

APPENDIX Oi

SECTION VI

201. Compare the average phosphorus content of the soils
of the British Isles with that of the common corn-belt prairie
land, and with that of the abandoned “ Leonardtown loam ’”’ of
Maryland.

202. How do you account for the great variation in phos-
phorus content of English soils of the same soil type or forma-
tion? (See also pages 304 and 324.)

203. Suggest some specific improvement which in your
opinion might well be made either in the textbook or in the
teaching of the subject.

ANNOUNCEMENTS

SOLE PERTILIFY AND
PERMANENT AGRICULTURE

By Cyrit GrorGE Hopkins, Professor of Agronomy in the University of Illinois; Chief
in Agronomy and Chemistry and Vice Director in the Illinois
Agricultural Experiment Station

8vo, cloth, xxiii + 653 pages, $2.25

‘Soil Fertility and Permanent Agriculture ”’ sets forth many facts
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that the present most common American practices in the art of agri-
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world,” lead absolutely toward land ruin not only for the grain farmer
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To prevent this depletion of soil fertility, the basic support of
every form of agriculture, Professor Hopkins gives statistics which
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Then, by a careful investigation of the agricultural processes to which
those soils have been submitted, and of the experiments conducted
by the agricultural stations in those districts, he explains the proc-
esses by which the land shall be brought to its greatest productivity.

SOIL PER TILITY
EaaOrmALORY MANUAL

By Cyrit GrorGce Hopkins, Professor of Agronomy in the University of Illinois, and
Vice Director in the Illinois Agricultural Experiment Station; and JAmMEs
Harvey Perrir, Assistant Professor of Soil Fertility in the College of
Agriculture, and Assistant Chief of Soil Fertility in the Agri-
cultural Experiment Station, University of Lllinois

8vo, cloth, vi+ 70+ 12 pages, 60 cents

A GUIDE to laboratory work in soil fertility, including experiments
outlined to help the student to appreciate the amount of plant food
removed from soils in cropping by various systems, the total stock
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plant food may best be maintained or increased.

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THE PRINCIPLES OF BREEDING: THREMMATOLOGY

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SOIL FERTILITY AND PERMANENT AGRICULTURE

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Chief in Agronomy and Chemistry and Vice Ee in the Illinois Agricultural
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A BOOK of the times, for the farmer and eral student. By means of
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EXAMINING AND GRADING GRAINS

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