ACKNOWLEDGMENTS OF ILLUSTRATIONS

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

CONTENTS

SOILS, THEIR ORIGIN AND CLASSIFICATION

CHAPTER

INTRODUCTION

I. THE SOIL AND ITS ORIGIN.

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

3. The Weathering Agents: (a) Heat and cold, (b) frost, (c)

wind, (d) ice, (e) water, (f) gases; aided by other forces of

nature and by plants and animals. 4. Soil Formation Is a

Complex and Slow Process. 5. Most Soils are Carried Away

or Moved After They Form. 6. Soil of Many Kinds.

II. SOIL COMPOSITION, CLASSES AND TYPES.

1. Common Meanings of Soil and Subsoil. 2. The Compo-

sition of Soil: (a) Mineral particles sand, silt, clay-from

rock. (b) Organic matter remains of plants. 3. Soil a

Complex Medium for Plant Growth: (a) Sand, silt, clay con-

stitute the framework-and contains: (b) water (moisture);

(c) soil organisms; (d) air; (e) salts in greater or less amounts.

4. Soil Classification: (a) On the basis of texture (grouped

into classes): sand, fine sand, sandy loam, fine sandy loam,

loam, slit loam, clay loam and clay. (b) On the basis of mode

of formation: residual, cumulose, alluvial, glacial, marine,

lacustrine, loess and colluvial. (c) On the basis of types

(grouped into series): Dunkirk sand, Genesee loam, Knox

silt loam, Cecil loam, etc., as types.

SOILS FROM A CHEMICAL POINT OF VIEW

III. CHEMICAL COMPOSITION OF SOILS AND ITS RELATION TO PLANTS

AND ANIMALS.

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

IV. How ROCKS AND CLIMATE AFFECT SOILS.

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

2. A Rock is an Aggregate of Mineral Particles. 3. Rock

Minerals the Sources of Mineral Plant-food Elements.

4. The Relation Between the Presence of Particles of Rock

Minerals and the Richness of Soils. 5. Products of Rock

Weathering: (a) Sand, silt, clay-breaking-up products;

(b) True clay (kaolin). (c) Carbonate of lime. (d) Salts.

6. Different Soils from Different Rocks. 7. The Effect of

Climate on Soils: (a) Soils in humid regions are leached.

(b) Alkali soils-formed in dry regions. (c) Much organic

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CHAPTER

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

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

found in humid regions.

SOIL AND PLANT RELATIONS

IV. SOIL AN IMPORTANT FACTOR AFFECTING PLANT GROWTH.

1. Conditions Surrounding Plants Must be Favorable.

2. Three Periods of Life History of Plant Passed in Contact

with the Soil. 3. The Germination Period: (a) Life in seed

strives for existence. (b) Requirements-moisture, oxygen,

favorable temperature and good tilth. (c) Tilth, good tilth,

poor tilth defined. (d) Absorption of water by seeds influ-

enced by contact between soil and seed, moisture, warmth

and presence of salts. 4. The Vegetative or Growing Period:

(a) Period of greatest activity. (b) Conditions and require-

ments. (c) Full meaning and importance of good tilth,

factors affecting development. (d) Availability of plant-food

elements. (e) Special function of the plant-food elements.

5. The Fruition Period.

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VI. CROPS AS FEEDERS ON THE PLANT-FOOD ELEMENTS IN THE SOIL 61

1. Soil Particles are not Plant Foods. 2. Amount of Ele-

ments Removed by Harvested Crops. 3. Some Facts Con-

cerning the Feeding of Crops: (a) Most of phosphorus goes

into grain, and potassium into stalk and straw. (b) All

plants do not take the same amounts of the elements. (c)

Alfalfa a "heavy feeder." (d) Timothy is not a "soil rob-

ber." (e) Some plants have strong feeding powers. (f)

Barley requires a richer soil than oats. (g) Fertilizer needs

best determined by tests. 4. Amount of Plant-food Ele-

ments Removed by Fruit Crops. 5. Supply of Nitrogen,

Phosphorus and Potassium in Soils: (a) Supply varies in

different soils. (b) Per cent vs. pounds of plant-food ele-

ments in soils. (c) Peat soils are usually deficient in the

mineral elements (K and P). (d) Peat lands are sometimes

deceptively advertised. (e) Subsoils contain plant-food

elements.

CROP PRODUCTION

VII. CROP PRODUCTION AND SOIL FERTILITY.

1. Factors in Successful Crop Production: (a) Fertile soil,

determined by moisture in soil, air in soil, good tilth, pres-

ence of helpful organisms, plant-food elements, absence of

harmful agents. (b) Good seed: high test, adaptability,

purity, disease resistant, high yielding, etc. (c) Favorable

temperature. (d) Light: some crops require much light,

some less; shading a factor in weed-killing; weeds may shade

crops; one crop may deprive another of light. (e) Protection

from injury: proper fencing, spraying, treating seed, drain-

age, etc. 2. Soil Fertility (Defined). 3. Factors which

Determine Soil Fertility Same as Those Which Make a Fertile

Soil. 4. Soil Exhaustion: (a) Illustrated by draft upon the

phosphorus supply. (b) Soil exhaustion usually the result

of the removal of organic matter; the removal of available

plant-food elements; the removal of carbonate of lime;

improper tillage. 5. Most Soils can be Improved in

Some Way.

75

CONTENTS

FACTORS DETERMINING SOIL FERTILITY

VIII. SOIL WATER AND ITS RELATION TO SOIL FERTILITY. . .

1. Why Plants Require Water. 2. Crops Require Much

Water. 3. Water Requirements of Some Crops-Based on

Dry Matter Produced. 4. Water Commonly Limits Crop

Production. 5. Forms of Soil Water-Gravitational, Capil-

lary and Hygroscopic. 6. Capillary Water of Most Import-

ance: Held by soils in form of films around the soil particles,

in organic matter, and within soil crumbs. 7. Movements

of Water in Soils: Percolation, seepage, capillary rise of

water. 8. Water-holding Capacity of Soils. 9. Moisture

Conservation and Control-(a) Lessen surface run-off by

aiding soils to trap water. (b) Increase water-holding

capacity by adding organic matter. (c) Aid capillary rise of

moisture by compacting the seed bed. (d) Lessen surface

evaporation by developing a soil mulch. (e) Conserve mois-

ture by killing weeds.

IX. LAND DRAINAGE AND IRRIGATION.

1. Too Much Water is Harmful. 2. Benefits of Proper

Drainage. 3. How Drainage is Accomplished: (a) Surface

drainage. (b) Subsurface drainage. (c) Vertical drainage.

(d) Combined methods. 4. Tile Drainage: (a) Drain tile

and how they are laid. (b) Distance to lay lines of tile. (c)

Systems of tile drainage natural, gridiron, herring-bone

and combination of systems. (d) Cost and benefits of tile

drainage. 5. Drainage by Means of Pumps. 6. Irrigation

Defined: (a) Objects of irrigation and how irrigation water

is secured. (b) How irrigation water is applied-flooding,

furrow irrigation, spray irrigation and sub-irrigation. (c)

Irrigated farms require good management. (d) Many

irrigated lands need drainage. (e) Profits in irrigation

farming. (f) Irrigation an art of antiquity.

X. TILTH AND TILLAGE.

1. Tilth and Tillage in General: (a) Factors determining

development of good tilth. (b) Tillage tools are many. (c)

Objects and principles governing tillage. 2. Preparing the

Seed Bed: (a) Plows and plowing. (b) Subsoiling, deep till-

ing and dynamiting soils. (c) Harrows and harrowing. (d)

Rollers, plankers and clod crushers. 3. Seeding and Plant-

ing: (a) Good firm seed bed favors planting. (b) Drills vs.

broadcast grain seeders. (c) When discing is better than

plowing. (d) Listing. 4. Cultivation and Intertillage:

(a) Why crops are cultivated. (b) Cultivators and their

adaptability. (c) When and how to cultivate.

XI. SOIL ORGANISMS IN RELATION TO SOIL FERTILITY..

1. Organisms of Decomposition: (a) No crops without de-

cay. (b) Organisms cause decay of organic matter. (c) Decay

of organic matter aids decay of mineral particles. (d) Some

fertilizers would be valueless without decay. 2. Bacteria

Which Cause Nitrification: (a) Importance of nitrification.

(b) Catch and cover crops conserve nitrates. (c) Nitrifica-

tion results in loss of organic matter. 3. Bacteria which Fix

Atmospheric Nitrogen in Soils: (a) Two groups of nitrogen-

fixing bacteria. (b) Amount of nitrogen gathered per acre.

(c) How nodule bacteria work. (d) How the growing of

legumes improves soils. (e) Soil inoculation and methods.

(f) Conditions favoring soil bacteria.