Franklin Stewart Harris.

The principles of agronomy; a text-book of crop production for high-schools and short-courses in agricultural colleges online

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I



RURAL TEXT-BOOK
SERIES




PRINCIPLES

OF
AGRONOMY




HARRIS S. STEWART



Jllili



L, H. BAI LE

EDITOR



WBaaaaaeKoanaj



-.■-4b.



XTbe IRural TLcxUBoo\\ Series

Edited by L. H. BAILEY



THE PRINCIPLES OF AGRONOMY



Eht Eural Erxt^Book Series

Editkd by L. H. bailey

Ma7in, Beginnings in Agriculture,

Warren, Elements of Agriculture.

Warren, Farm Management.

Lyon, Fippin and Buckman, Principles of
Soil Management.

J. F. Duggar, Southern Field Crops.

B. M. Duggar, Plant Physiology, with
special reference to Plant Production.

Harper, Animal Husbandry' for Schools.

Montgomery, The Corn Crops,

Wheeler, Manures and Fertilizers.

Livingston, Field Crop Production.

Widtsoe, Principles of Irrigation Prac-
tice.

Piper, Forage Plants and their Culture.

Hitchcock, A Text-book op Grasses.

Gay, The Principles and Practice of
Judging Live-Stock.

White, Principles of Floriculture,



THE PRINCIPLES OF
AGRONOMY



A TEXT-BOOK OF CROP PRODUCTION FOR HIGH-
SCHOOLS AND SHORT-COURSES IN
AGRICULTURAL COLLEGES



BY

FEANKLIN S: HARRIS, Ph.D.

PE0FE8S0K OF AGKONOMY AND DIRECTOR OF THE SCHOOL OF AGBICULTtTKAL
ENGINEERING, UTAH AGRICULTURAL COLLEGE



GEORGE STEWART, B.S.

INSTRUCTOR IN AGRONOMY, UTAH AGRICULTURAL COLLEGE



THE MACMILLAN COMPANY
1915

All rights reserved



YV\



vi Preface

ences have been made to state experiment station pub-
lications, since many of them are not available.

The teaching of agriculture is valuable only as it
is made practical. It is suggested, therefore, that stu-
dents work in the laboratory and field as much as
possible in order to become directly familiar with soils,
crops, and applications of principles instead of relying
solely upon what the text says about them.

The authors are indebted to a number of their col-
leagues at the Utah Agricultural College for encour-
agement and friendly criticism during the preparation
of this book. They are under special obligation to
President J. A. Widtsoe, Director E. D. Ball, Pro-
fessor N. A. Pederson, and Messrs. A. F. Bracken,
C. L. Anderson, and N. I. Butt, all of whom have
read the manuscript and offered valuable suggestions.

FRANKLIN S. HARRIS,
GEORGE STEWART.
Logan, Utah,

May 1, 1915.



CONTENTS

CHAPTER I

PA6K8

Introductory ......... 1-5

What is agriculture ? 1 i Agriculture and the sciences,
2 ; Agriculture and the industries, 2 ; Opportunities in
agriculture are varied, 3 ; Divisions of agriculture, 4 ;
Phases of agTonomy, 4 ; Scope of this book, 4.

PART I. THE PLANT

CHAPTER II

Thk Plant and Its Environment 9-22

Factors of plant growth, 10 ; Length of season, 12 ;
Frost, 13 ; Temperature, 14 ; Water, 16 ; Sunlight, 18 ;
Wind, 19 ; Soil, 19 ; Pests, 20 ; Adapted crops, 21.

CHAPTER III

Plant Structure ........ 23-38

Cells, 23 ; Tissues, 25 ; Kind of plant, 26 ; Crop plants,
26 ; Plant parts, 27 ; The root, 27 ; The stem, 30 ; The
leaf, 35 ; The flower, 35 ; The seed, 37 ; Buds and
branches, 37 ; Underground stems, 37.

CHAPTER IV

Plant Functions 39-49

Growth, -39 ; Respiration, 41 ; Photosynthesis, 42 ;
Osmosis, 44 ; Transpiration, 46 ; Translocation, 48 ;
Transportation, 48 ; Response, 49.



viii Contents



CHAPTEU V

PAGES

The Plant as a Factory 50-63

Interdependence of plants and animals, 51 ; Depend-
ence of man on plants, 51 ; Domestication, 53 ; Plant
compounds, 54 ; Flavors, 54 ; Water, 55 ; Carbohydrates,
55 ; Protein, 56 ; Ash, 56 ; Fats and oils, 56 ; The plant
factory, 57; Animal concentration, 59; Storage, 59;
Harvest, 61 ; Control of the harvest, 62.



PAET II. THE SOIL

CHAPTER VI

What the Soil Is 67-69

Definition, 67 ; Permanence of soils, 68 ; Economic
importance of the soil, 68 ; Conservation of the soil, 68 ;
Need of better soil management, 69.

CHAPTER Vll

Origin and Formation of Soils 70-80

Minerals and rocks, 70 ; Soil-forming minerals, 70;
Quartz, 71 ; The feldspars, 71; Hornblende and pyrox-
ene, 71 ; Mica, 71 ; Chlorite, 72 ; Zeolites, 72 ; Calcite,
72 ; DolQmite, 73 ; Gypsum, 73 ; Apatite, 73 ; Soil-form-
ing rocks, 73 ; Methods of soil formation, 74 ; Action of
heat and cold, 74 ; Action of v?ater, 75 ; Ice, 76 ; The
atmosphere, 78 ; Plants and animals, 78 ; Classification
of soils, 79.

CHAPTER VIII

Physical Properties of the Soil 81-89

Soil texture, 81 ; Groups according to texture, 82 ; Re-
lation of texture to water-holding capacity, 83; Soil
structure, 83 ; How to modify structure, 84 ; Specific
gravity of soils, 86 ; Air in the soil, 86 ; Heat of the soil,
87 ; The organic matter of the soil, 88 ; Maintaining the
organic matter, 88.



Contents ix



CHAPTER IX

PAGES

The Water of the Soil ....... 90-97

Origin of soil water, 90 ; Variations in soil moisture,
91 ; The condition of soil moisture, 91 ; Free water, 91 ;
Capillary water, 92 ; Hygroscopic water, 92 ; Other crit-
ical points, 93 ; Quantity of water in field soils, 9.3 ;
Methods of expressing the quantity of water, 94 ; Loss
of soil moisture, 9-1 ; Need for preventing evaporation,
94; The water-table, 95; The movements of soil mois-
ture, 96 ; Use of soil water, 90 ; Quantity of water used
by plants, 96.



CHAPTER X

The Control of Soil Water 98-117

Irrigation : Increasing the soil moisture, 98 ; Sources
of water supply, 100 ; Measurement of water, 102 ; Meth-
ods of applying water, 103 ; The amount of water to use,
104 ; When to irrigate, 105 ; Over irrigation, 106 ; Need
for economy, 106. Drainage : Removing excessive
water, 107 ; Removing alkali, 108 ; Benefits of drainage,
108 ; Kinds of drainage, 109 ; Installing the drains, 110.
Dry-farming: Scope of dry-farming, 111; The ques-
tion of rainfall. 111; Dry-farm soils, 113; Dry-farm
crops, 115; Tillage methods, 116.



CHAPTER XI

Plant-food of the Soil ....... 118-124

What plants use from the soil, 118 ; Composition of
soils, 119 ; The analysis of soils, 120 ; Available and re-
serve plant-food, 121 ; Making plant-food available, 121 ;
Quantity of plant-food removed by plants, 121 ; Plant-
foods that are scarce, 122 ; Exhausticm of the soil, 123 ;
Losses in plant-food, 123 ; Plant-food in organic matter,
124 ; Relation of plant-food to value of a soil, 124.



Contents



CHAPTER XII

PAGES

Manures and Fertilizers 125-137

Types of fertilizers, 126 ; How to determine fertilizer
needs, 126; Nitrogen fertilizers, 127; Nitrogen fixation,

128 ; Phosphorus fertilizers, 128 ; Potassium fertilizers,

129 ; Lime, 129 ; Indirect fertilizers, 130 ; Home-mixing
of fertilizers, 130 ; Value of farm manure, 131 ; Kinds
of farm manure, 132 ; Losses in manure, 133 ; Handling
farm manure, 131 ; How to fertilize different crops, 136 ;
Green manures, 136.

CHAPTER XIII
Organisms of the Soil ....... 138-144

Kinds of soil organisms, 138; Bacteria, 139; The
number of bacteria in the soil, 139 ; Kinds of bacteria,
139 ; How bacteria grow, 140 ; Relation to humus for-
mation, 141 ; Relation to nitrogen, 141 ; The fixation of
nitrogen, 142 ; Nitrification and denitrification, 143 ;
Bacteria and the farmer, 144.

CHAPTER XIV
Tillage and Crop Rotations ...... 145-153

Improving soil structure, 145 ; Controlling weeds, 147 ;
Covering manure and plant residues, 148 ; Conserving
moisture, 149 ; Tillage of various crops, 150 ; Reasons
for rotation of crops, 151 ; Methods of crop rotation, 152.

CHAPTER XV

Special Soil Problems 154-163

Alkali : Kinds of alkali, 155 ; Effect of alkali on plant
growth, 156 ; Reclamation of alkali lands, 156. Acidity :
Indicators of a soil acidity, 157 ; Correction of soil
acidity, 157. Erosion : Methods of preventing erosion,
158. Blowing : Prevention of blowing, 160. Methods
of judging soils : Indicator value of native vegetation,
161 ; Topography of the land, 161 ; Depth and structure
of the soil, 162 ; Chemical analysis, 162 ; Mechanical
analysis, 163 ; Productivity, 163.



Contents xi



PART III. FIELD CROPS
CHAPTER XVI

PACiES

Wheat 167-190

Relationships, 1(38 ; Roots, 168 ; The plant above
ground, 170 ; The kernel, 170 ; Varieties, 171 ; Distri-
bution and adaptation, 173 ; Preparation of seed-bed,
175; Seed and seeding, 175 ; Harvesting, 178 ; Diseases,
179 ; Closed smut, 179 ; Loose smut, 180 ; Rust, 180 ;
Insects, 180 ; Weeds, 181 ; Quality in wheat, 182 ; Uses
and value, 183 ; Storage, 184 ; Elevators, 186 ; Market-
ing, 187 ; Prices, 188.

CHAPTER XVII

Corn or Maize 191-207

Relationships, 191 ; Roots, 192 ; The culms, 193 ; The
leaves, 193 ; The flower, 194 ; The ear, 194 ; Types, 195 ;
Dent corn, 195 ; Plint corn, 196 ; Sweet corn, 196 ; Pop
corn, 196 ; Soft or flour corn, 197 ; Pod corn, 197 ; Va-
rieties, 197 ; Distribution, 197 ; Factors in production,
198 ; Adaptation, 198 ; Preparation of the seed-bed, 199 ;
Seed and planting, 200 ; Treatment of the growing crop,
201 ; Harvesting, 203 ; Silage, 203 ; Enemies, 204 ; Uses
and value, 204 ; Storage and marketing, 205.

CHAPTER XVIII
Other Cereals 208-223

Oats : Origin and relationships, 208 ; Description, 209 ;
Distribution, 210 ; Varieties, 212 ; Seeding and cultiva-
tion, 212 ; Harvesting and marketing, 212 ; Uses, 213 ;
Enemies, 214. Barley : Description, 215 ; Distribution
and adaptation, 216 ; Sowing and cultivation, 216 ; Har-
vesting and marketing, 217 ; Enemies and uses, 218.
Bye : Description and distribution, 219 ; Handling the
crop, 220 ; Uses, 220. Bice : Description and distribu-
tion, 221 ; Uses, 221. Enemies: Description and use,
222. Buckwheat : Description, distribution, and uses,
222.



xii Contents



CHAPTER XIX

PAGES

Potatoes 224-240

Origin, 224 ; Relationships, 225 ; Description, 225 ;
Varieties, 227 ; Distribution and adaptation, 228 ; Prep-
aration of land, 230 ; Seed, 231 ; Cutting and planting,
233 ; Treatment during growth, 234 ; Harvesting and
marketing, 235 ; Storage, 235 ; Weeds and insects, 236 ;
Diseases, 236 ; Use and value, 239.

CHAPTER XX

Root Crops 241-255

Stig ar -beets : History,, 241 ; Description, 243; Adap-
tation and distribution, 243 ; Preparation of the land,
seed, and seeding, 245; Treatment during growth, 247 ;
Diseases, 248 ; Insects, 249 ; Harvesting, marketing, and
storage, 249 ; Use and value, 250 ; Manufacture of sugar,
251. Mangel-ivurzels : Description, 251 ; Use, 2-52 ;
Culture, 252. Turnips and Rutabagas : Description,
253 ; Culture, 253 ; Value, 254. Carrots : Description,
264 ; Culture and use, 255.

CHAPTER XXI

Alfalfa 256-270

Name and origin, 256 ; Relationships, 258 ; Roots,
258 ; Stems and leaves, 259 ; Flowers and seed, 260 ;
Varieties, 261 ; Distribution and adaptation, 261 ; Prep-
aration of the land and seeding, 263 ; Treatment during
growth, 263 ; Harvesting, 264 ; Storage, 265 ; Use and
value, 266 ; Mixtures, 267 ; Enemies, 268 ; Seed produc-
tion, 269.

CHAPTER XXII

The Clovers and Other Legumes ..... 271-285
Bed clover : Description, 272 ; Distribution and adap-
tation, 272 ; Culture, 273 ; Use and value, 273. Other
clovers : Alsike clover, 274 : White clover, 274 ; Sweet
clover, 274 ; Crimson clover, 275. Field Peas : Descrip-



Contents



Xlll



tion and adaptation, 275 ; Sowing, 276 ; Culture and
harvesting, 277; Use, 277. Beans: Description, 278;
Culture, 278 ; Use, 280. Cowpeas : Description, 280 ;
Culture, 282. Soybeans : Description, 282 ; Cul-
ture, 283. Miscellaneous Legumes : Vetch, 284 ; Other
legumes, 284.

CHAPTER XXIII

Grasses 286-301

Timothy : Description, 288 ; Adaptation, 289 ; Cul-
ture, 289 ; Use and value, 291 ; Enemies, 292. Bedtop :
Description, 292 ; Adaptation, 292 ; Culture, 293 ; Value
and use, 293. Kentucky Blue-grass : Description, 293 ;
Adaptation, 294 ; Culture, 294 ; Use and value, 294.
Orchard- grass : Description, 29.5 ; Adaptation, 29.5 ; Cul-
ture, 295 ; Value and use, 296. Smooth Brome-grass :
Description, 297 ; Adaptation, 297 ; Culture, 297 ; Value
and use, 298. Other grasses: Tall meadow oat-grass,
299 ; Bermuda-grass, 299 ; Johnson-grass, 300 ; Miscel-
laneous grasses, 301.



CHAPTER XXIV

Pastures, Meadows, and Soiling Systems

Definition, .302 ; Kinds of pasture, 302 ; A good pas-
ture, 303 ; Importance, 303 ; Native grass, 304 ; Crop
plants, 304 ; Mixtures, 304 ; For different animals, 307 ;
Condition of pastures, 308 ; Improving pastures, 308 ;
Over-stocking, 309 ; Management, 310 ; Meadows, 311.
Soiling : Use, 312 ; Value, 312; Soiling crops, 316.



302-317



CHAPTER XXV

Sorghums and Millets

Sorghum: Origin, 318; Relationships, 320 ; Descrip-
tion, 320 ; Varieties, 322 ; Distribution and adaptation,
323 ; Preparation of seed-bed and seeding, .325 ; Treat-
ment during growth, 325 ; Harvesting, 326 ; Use, 327 ;
Enemies, 328 ; Storage and marketing, 328. Sudan-
grass : Description, 329 ; Culture, 329. Millets : Rela-
tionship and description, 330 ; Culture and value, 330 ;
Other types, 331.



318-3.32



xiv Contents



CHAPTER XXVI

PAGES

Fibers and Miscellaneods Crops ..... 333-352

Fibers : Cotton. History, 333 ; Relationships, 334 ;
Description, 335 ; Adaptation, 335 ; Culture, 336 ; Har-
vesting and marketing, 337 ; Use, 337. Flax: Descrip-
tion, 338 ; Adaptation, 338 ; Culture, 338 ; Use and
value, 340. Other fibers : Hemp, 340 ; Miscellaneous
fibers, 341. Miscellaneous crops : Cabbage and kohl-
rabi, 342 ; Rape, 343 ; Kale, 343 ; Enemies, 343. To-
bacco : Distribution, 345 ; Culture, 345 ; Curing and
marketing, 345 ; Sugar-cane, 346 ; Sweet potatoes, 347 ;
Fruits, 349 ; Truck crops, 349 ; Timber crop, 351 ; Other
crops, 351.

CHAPTER XXVII

Improvement of Crop ....... 353-365

What is improvement ? 354 ; Ideal sought, 356 ;' Cul-
tivation, 357 ; Seed-testing, 367 ; Reproduction, 359 ;
Variation, 359 ; Natural selection, 360 ; Artificial selec-
tion, 360 ; The be.st plants should be chosen, 361 ; Va-
riety tests, 362 ; Steps in breeding, 362 ; Crossing, 362 ;
Mendel's law, 363 ; Importance of large numbers, 364 ;
Better seed, 364.

CHAPTER XXVIII

Weeds 366-378

Definition, 366 ; Classification, 367 ; Occurrence, 368 ;
Dissemination, 364 ; Losses from v^eeds, 370 ; Preven-
tion, 372 ; Eradication, 373 ; General principles, 375 ;
Herbicides, 376; Summary, 377.

PART IV. FIELD MANAGEMENT

CHAPTER XXIX
Planning the Farm ........ 381-386

Plan should be stable, 381 ; Number of enterprises,
383 ; The farmstead, 383 ; Arrangement and number of
fields, 384 ; Size and shape of fields, 384 ; Fences and
ditches, 385 ; Use of waste places, 386.



Contents xy



CHAPTER XXX

PAGES

What Crops to Grow 387-391

Crop adaptation, 387 ; Diversity of crops, 388 ; CroQ
specialties, 389; Conditions for various crops, 391;
Work in producing various crops, 391.



CHAPTER XXXI ,

Equipment of the Farm ....... 392-399

The farmer as a mechanic, 392 ; Extremes in farm
equipment, 393 ; Machines that get out of date, 394 ;
Machines that are seldom used, 395 ; Size of machinery,
395 ; The duty of machinery, 395 ; Depreciation, 396 ;
Caring for machinery, 397 ; Suitable farm buildings, 398.

CHAPTER XXXII

Factors of Success in Crop Production . . . 400-406

Size of farm, 300 ; Capital, 401 ; Proper type of farm-
ing, 402 ; Good management, 402 ; Keeping records,
403 ; Profits to a farmer vs. yields to the acre, 403 ;
Profits from man and horse labor, 404 ; Understanding
each crop, 404 ; Markets, 404.

APPENDICES .... 407-430

Addresses of Agricultural Colleges and Ex-
periment Stations and of the United States
Department of Agriculture . . . 408

Laboratory Guides 411

Fertility in Farm Pi'oduce .... 412

Composition, Amount, and "Value of Manure
Produced by Different Kinds of Farm

Animals 413

Weights and Measures ■ 414

Quantity of Seed Planted to the Acre . . 416

Most Common Weights of Seeds to the

Bushel 417



Appendix


A.


Appendix


B.


Appendix


C.


Appendix


D.


Appendix


E.


Appendix


F.


Appendix


G.



XVI



Contents



PAGE

Appendix H. Measuring Rules 418

Appendix I. Rules for Measuring Hay in the Stack . . 419

Appendix J. Wheat Harvest Calendar .... 420
Appendix K. Prices of Wheat on a Chicago Market (1863-

1910) 421

Appendix L. Crop Statistics for Continental United States 423

Appendix M. Plowing as affected by Shape of the Field . 424
Appendix N. Average Depreciation a Year and Cost to

the Acre for Farm Machinery . . . 425

Appendix O. Glossary 426



THE PRINCIPLES OF AGRONOMY



THE PRINCIPLES OF AGRONOMY



CHAPTER I
INTRODUCTORY

Agriculture is so broad in its scope and practice, that
it is related to almost every branch of human learning.
All the industries and professions of man are in some
way connected with the land and its products. The
welfare of manufacturer, merchant, railroad man, lawyer,
and doctor is so dependent on agricultural prosperity
that these men are necessarily interested in this great
subject. Since agriculture embraces such a wide field,
it is necessary to define and subdivide, in order to obtain
a clear idea of its various branches.

1. What is agriculture? — Agriculture may be defined
as the art, the science, and the business of producing
plants and animals for economic purposes.

As an art, it embraces aFnowledge of the way to per-
form the operations of the farm in a skillful manner,
but does not necessarily include an understanding of the
principles underlying farm practices. The ability to
plow well, to make a good stack of hay, and to handle
live-stock indicates training in the handicrafts of agri-
culture.

The science of agriculture deals with the principles
underlying the production of plants and animals, with-
out regard to skill in the practices of farming. A person
B 1



2 The Principles of Agronomy

may understand the methods by which hay is digested
in the stomach of a cow, and how milk is secreted ; he
may be familiar with the composition of milk and the
processes it undergoes in the manufacture of butter or
cheese ; and still he may not know how even to milk a
cow. He has training in the underlying scientific prin-
ciples of agriculture, but not in the art or handicraft.

Agriculture is a business, since it is practiced primarily
as a means of securing a living. Usually a farmer is not
interested in the art and science of agriculture except as
they contribute to his making a better livelihood. Science
helps him to understand why he does certain things, and
gives him a foundation for his practices ; he acquires skill
in the practices in order to increase production and,
through it, to extend his income.

2. Agriculture and the sciences. — The assertion is
sometimes made that if a person were familiar with all
the sciences, he would not need to study agriculture.
This is probably true, but no one person is able to master
all the sciences ; even if he were able to do so, he would
need to learn some of the applications of science to the
land before finishing his studies of pure science.

The real condition, however, is that those who have
most to do with the land have little time for extensive
study of science, although they desire a brief knowledge
of some of the principles underlying the industry in which
they are engaged. This justifies the teaching of agri-
culture even to those who have had little training in the
so-called pure sciences. The better one understands the
natural and social sciences, however, the better will one
be able to comprehend the principles and problems of
agriculture.

3. Agriculture and the industries. — Agriculture is at
the very foundation of all industries. Manufacturing,



Introductory 3

mining, and commerce are dependent on the products of
the soil for their existence ; indeed, the very Hfe of man
himself would be impossible if the soil did not directly
or indirectly yield him food. The advance of civiliza-
tion and the development of industrial enterprises are
limited by the agricultural conditions of the world. Agri-
culture, instead of being a problem merely for those en-
gaged directly in its practice, is a world problem affecting
all the activities of man. It is evident, therefore, that
it merits serious consideration.

The farm, in addition to being a place where a great
industry is condvicted, is a home for those engaged in
this industry. It should, therefore, be considered not
entirely from the point of view of economic efficiency,
but of social efficiency also, as the home of that part
of the coming generation which will probably have
most to do with the future welfare of the nation. Agri-
culture, as a consequence, has social and educational
aspects quite as important as its scientific and economic
phases.

4. Opportunities in agriculture are varied. — The most
important opportunities are those connected with the
work on the land in its various phases. Never in history
has the land called with a louder voice than at present,
for young men of intelligence, industry, and training.
There are opportunities on every hand for him who knows
how to use the forces of nature, and who can secure joy
and satisfaction in being a direct producer.

Other phases of agriculture, such as teaching it in the
schools, engaging in demonstration and experimental
work for the states and the government, and working as
an expert adviser for corporations, are assuming greater
importance every year, and offer good opportunities to
young men of ability and training.



4 The Principles of Agronomy

5. Division of agriculture. — Agriculture may be sub-
divided in many ways. It may be classed as intensive
or extensive, specialized\ or diversified, exploitive or
restorative, tropical or temperate ; or it may be divided
according to the source of income. For instructional
purposes in agricultural colleges, it has often been divided
into three main parts : agronomy, animal husbandry,
and horticulture.

The subject of agronomy has usually included a study
of^soils, field crops, and farm management. Under animal
husbandrypEhe various phases of the live-stock indus-
try, including dairying, have been studied. The study
of horticulture has included the production of fruits,
vegetables, and flowers.

In addition to these three applied divisions, there are
also a number of scientific divisions, such as entomology,
chemistry, and plant and animal pathology. Each of
these bears a relation to all three of the applied divisions.
It is difficult, therefore, to find a subdivision of agriculture
that is logical and at the same time entirely practical,
since the difi^erent branches are so closely interrelated.

6. Phases of agronomy. — The present volume deals
with that phase of agriculture sometimes called agronomy.
The meaning of this word is not widely known outside
of the schools, and even there it is used somewhat loosely.

It comes from two Greek words meaning " the use of (.J
fields." At present, it is usually understood to mean the
management of the land in the production of field crops.
It is sometimes divided into three distinct phases : soils,
crops, and farm management. The term " agronomy "
may be applied to any one of these branches.

7. Scope of this book. — To give the beginner in
agricultural study a general idea of the principles of suc-
cessful production of crops, and to furnish him a basis for



Introductory 5

study in the other branches of agriculture, is the object
of the present volume.

Part I discusses the principles of plant growth, and
will be of service to students who later take up horticulture
as well as to those studying agronomy. In Part II, a
study is made of the soil and its management. This
part is likewise fundamental to horticulture as well as to
agronomy. Part III is devoted entirely to the study of
field crops ; and in Part IV, numbers of problems relating
to field management are discussed.. Some of these also
apply to other phases of agriculture.



PART I
THE PLANT



CHAPTER II
THE PLANT AND ITS ENVIRONMENT

On every side are evidences that plants (Jjear more or
less definite relations to the nature of their surroundings.
An environment that favors one crop may prevent the
culture of another. Tropical plants do not thrive in
temperate or frigid zones ; neither do lilies grow in deserts,
nor roses on barren cliffs.

Great forests spread for hundreds of miles over cer-
tain sections ; wide grassy plains stretched almost end-
lessly east of the Rockies before settlement ; valleys in
the West were covered with sagebrush, except for patches
of willows or Cottonwood along the streams, or for rushes
and sedges in the sloughs. In many sections scrub oak
covers the foothills ; groves of quaking aspens line the
swales in the mountains ; pines and spruces cover the



Online LibraryFranklin Stewart HarrisThe principles of agronomy; a text-book of crop production for high-schools and short-courses in agricultural colleges → online text (page 1 of 28)