School agriculture, with experiments and exercises; a text book for rural and graded schools

Preface

WE are now in the midst of a great agricultural awakening. The population of the United States, which is increasing so rapidly as to be out of proportion to the increase in farm products, must be supplied with food; consequently, more land must be cultivated, haphazard methods of farming must be abandoned, and better systems along all agricultural lines must prevail. The trend of agricultural development is plainly visible. Soils once depleted by systems of farming which were the results of ignorance now respond to intelligent care by yielding bountiful crops; desert lands upon which grew scattering cacti and sage brush now produce under irrigation marvelous yields of fruit, vegetables, and other products; swamp lands, once thought worthless, are being drained and furnish homes for thousands of people; even soils that contained such large amounts of harmful salts as to make the growth of common plants impossible are being acted upon by irrigation and drainage until the salts are reduced to such an extent that farming is practicable.

In the past the tillers of the soil longed for the life of the city. At the present time, high prices and the attractiveness of country life cause city people to long for the farm, and "Back to the farm!" is the cry. All

PREFACE of this tends not only to arouse interest in agricultural problems, but to demand instruction in agricultural methods. A large part of such instruction must be done in the schools. The legislatures of a large number of states have placed agriculture in the common school curriculum as a result of the demands of the people. Truly this is a sensible thing to do. Why should not some of the time to be spent in school be used in acquiring knowledge of a subject which is not only of a disciplinary value, but which will help the pupils to earn a living?

While instruction in this subject in graded, and rural schools must be of an elementary character, it should be sufficiently comprehensive to include most of the principles of general agriculture; it should not deal entirely with theory; it should include demonstrations of practical value; and the subject should be taught so as to appeal to the intelligence of the pupil rather than to his memory.

It is for the purpose of promoting these ends that this book has been written. Throughout its preparation constant thought has been given the subject from the teacher's standpoint as well as from the pupil's. It is desired to make the work teachable. As the book is intended for classes in rural and graded schools, an effort has been made to have the language simple enough so that the pupils will find no difficulty in understanding

PREFACE the subject matter. Many interesting topics have been omitted, but it is hoped that those given are sufficiently comprehensive to be of lasting value to the pupil.

It is believed that the experiments, which follow each chapter, will prove of great value in making the subject a living subject, in connecting it with the home life of the pupil, in arousing the interest of the class, and in imparting knowledge of the fundamental principles of agriculture. Whether the exercises should precede the subject matter and the topics be developed inductively, whether they should be worked out in the class period, or whether they should follow as a means of illustrating principles under consideration, depends upon the class, the teacher, the time given to the particular topic, and the nature of the topic. The experiments are placed where the teacher can use the method best adapted to the conditions, and there are enough of them given so that selections can be made. It is not possible for most schools to have elaborate apparatus. The apparatus and materials necessary for performing the experiments given are very simple, easily obtained, and inexpensive.

It is of value to the pupils to make an extensive study of some branch of agriculture upon which particular attention is needed by people in the community. If the school is in an apple district, the growing of apples would form a profitable study; if in a potato belt, potato growing should be studied; if in a swamp region, the

PREFACE study of drainage would be profitable; if in an irrigated section, irrigation should receive special attention. Furthermore, it is of importance that the pupils be encouraged to read agricultural literature, such as bulletins farm papers, and books. As an aid to the teacher in accomplishing these purposes, a suggestive list of reference books follows each chapter.

Questions like those usually asked at the end of each chapter in most text-books of agriculture have been omitted, because it is believed that they are of no value to the teacher or to the pupils. On the contrary, they tend to make the work of the teacher mechanical and to discourage originality on the part of the pupil. Neither does a summary following each chapter aid to develop the thinking power of the pupil. A suggestive outline summary follows each chapter when it is deemed advisable to call the pupil's attention to particular points. For the most part the outlines are to be prepared by the pupil, and only a few suggestions in each case are given, to show him what is expected. After a pupil has completed an outline of this type, it should prove of assistance in topic recitations, in his written work on agriculture," and in reviewing. Its value will depend largely upon the extent of its use by the teacher.

A great deal of attention has been given to the illustrations in order to make them of practical use in developing the different topics.

PREFACE vii

It is hoped that this book will help to bring about a closer relation between the community and the school, as well as to help make the study of agriculture interesting and profitable.

Thanks are due the following for valuable suggestions, or for reading parts of the manuscript: W. A. Henry, Emeritus Professor of Agriculture, University of Wisconsin; G. H. Drewry, and W. H. Hunt, State School Inspectors of Wisconsin ; C. W. Burkett, Editor of the American Agriculturist; E. M. Griffith, State Forester of Wisconsin; Mary D. Bradford, Superintendent of the Kenosha Schools; W. E. Smith, Principal of the Reedsburg Training School for Teachers.

Grateful acknowledgment is made to the Orange Judd Company for many of the photographs and line drawings, also to the United States Department of Agriculture, and to the University of Wisconsin for a number of photographs.

Special acknowledgment is due to G. E. Culver, Professor of Chemistry and Geology, and W. F. Lusk, Professor of Agriculture and Physics in the State Normal School at Stevens Point, for carefully reading and criticizing the entire manuscript.

M. N. W.

Pittsvillle, Wisconsin, March, 1912.

Table Of Contents

TABLE OF CONTENTS

Chapter Page

I Soil Formation 1

Chapter I

MAN is the highest form of life upon this earth. He obtains his food from plants and animals. Animals obtain their food from other animals or plants, and plants depend upon the soil for part of their food supply.

We see, then, how important the soil is to all forms of life. Naturally, we desire to know what materials compose the soil, how it was formed, its relation to plant life, and the means by which man can c^id nature in bringing forth harvests from the ground.

How Soil Is Formed — If two pieces of sandstone are pounded together, they break up into small grains of sand. In other words, the small particles of rock have been caused to separate. There are many agents of nature that form soil by breaking up and dissolving rockmaterial, and that add organic matter by causing the decay of plants and animals. The following assist in forming soil:

1. Moving water.

2. Moving ice.

3. Heat and cold.

4. Winds.

5. Earthworms, ants, and living animals.

6. Living plants.

7. Gases in the air and water.

8. The decaying of plants and animals.

Moving Water — The amount of work done in soil formation by moving water is very great. The rain water from the eaves wears trenches in the ground, and in the course of time may wear depressions in solid rock. The amount of work that moving water can do is increased to a great extent when it carries some rock particles to help grind the rock. It also depends upon the quantity of water in motion, the velocity with which the water flows, and the hardness of the rock. Moving water transports soil material. As a

A Portion of a Flood Plain

Fig. 2. Soil Builders at Work Leaves, roots, stems, find their way back to the soil, and enrich It

stream will carry coarser particles where it is swift than where it is slow, the material deposited is sorted. Moving water, then, wears, carries, sorts, and deposits material.

The flood plains of rivers serve as examples of the work that moving water can do. Soils left by rivers in this way are called alluvial soils.

Moving Ice — Ages ago the northern part of North America was covered by a great ice sheet. As this large ice sheet moved slowly along, it scraped up sand, gravel and rocks, which it ground together until much of it was reduced to fine particles. Some of the hard rocks which were not completely pulverized had their corners worn off and are called glacial bowlders. The rocks over which the glacier passed are grooved and scratched because of the rock material frozen In the bottom of the glacier. When the ice melted, it left the soil and the bowlders all mixed together without any definite arrangement.

Because the material was not left in layers it is said to be unstratified; but in some cases it was sorted and deposited by the water which flowed from the melting glacier, therefore stratification resulted.

Heat and Cold —

Changes In temperature will cause pieces of rock to chip off. When the change of temperature is slow we may not notice this, but when it is rapid we sometimes see the effects in a short time. If a rock is heated and suddenly cooled by throwing on cold water, it is apt to break in pieces. The effect of a change in temperature becomes more prominent where the water freezes in the cracks of rocks ; the expansion of the freezing water causes the rocks to split. The great power exerted by freezing water is seen in the bursting of water pipes in winter.

Fig. 3. Section of Hill Left by Ice Sheet The materials are mixed together

Winds — When sand is blown violently against rocks, it possesses considerable cutting power. Winds also transport soil. Sometimes they leave the transported soil in large heaps, known as sand dunes.

Earthworms — Earthworms increase the porosity of the soil by digging tunnels in the ground where they live.

They bring the soil from these tunnels to the surface, where it is left in worm - shaped piles, called worm casts.

Darwin has stated that worms often bring as much as one inch of soil to the surface in five years. In this way the renewing of the top soil is continually going on. Worms also assist in adding organic matter by dragging partly decayed leaves and vegetable matter into the ground.

Ants — The work of ants in improving the soil lies chiefly in the tunnels which they dig. The earth does not pass through their bodies, as is the case with worms; consequently they do not materially aid in pulverizing the soil.

Fig. 4. Disintegrating Rock The foices of nature are gradually breaking up this rock

Other Animals — Other animals which burrow in the ground are gophers, field mice, moles, prairie dogs, and woodchucks. Their aid in soil formation is much less than that of earthworms or ants.

Fig. 5. Roots of Trees Breaking Up a Rocky Subsoil

Living Plants — The higher forms of plant life aid in breaking up rocks and in making the particles of soil finer. Not only do plant roots grow into the cracks of rocks and break off pieces, but they produce acids which dissolve some materials in the rocks.

Besides the higher plant forms, we find in the soil very small one-celled plants called bacteria. They are so small that hundreds of them could be placed on the point of a pin. There are various varieties of bacteria, as there are various varieties of corn or other plants. At present we do not fully understand all varieties of bacteria found in the soil, but we know that some of them cause the decomposition of organic matter, and that some fix nitrogen in the soil in a form that can be made use of by plants.

Gases in Air and Water — When water takes up carbon dioxide, its dissolving action on some rocks is greatly increased. Oxygen combines with the minerals of rocks and forms oxides. A familiar example is that of iron rusting. The crumbly iron rust, or iron oxide, is formed by the oxygen uniting with the iron.

The Decaying of Plants and Animals — Plants and animals decay and form the organic part of the soil. When partially decayed, they form humus. As has been said before, humus increases the moisture-holding capacity of the soil, regulates its temperature, and finally serves as plant food.

1. If you can observe the ice in a lake or a river when it breaks up in the spring, notice its grinding effect. How does it act on the banks?

2. Notice how water affects the roadside after heavy rains. Observe the action of small streams swollen after heavy rains. Is the water muddy? Where did the stream get the material which It carries? Where will this material settle?

3. Experiment to show the power of water and frost: Fill a glass bottle with water and cork It. Leave this out of doors overnight when the temperature Is below the freezing point. What happens to the bottle? What would you expect to see happen when water freezes In the cracks of rocks?

4. Observation of the work of earthworms: Earthworms do most of their work at night. Notice that they come out of the ground after heavy rains. Look for worm casts on the ground In the morning. Is the soil In these casts finer or coarser than the soil In the ground?

5. If you live In a territory over which the Ice sheet passed, examine the glacial bowlders. Observe the grooves and scratches In the rocks. How were they made?

6. Experiment to show how water causes stratification by sorting and depositing the material: Put some soil Into a jar of water and shake vigorously. After It has stood awhile, observe that the coarser particles are at the bottom of the jar and the finer material on top.

Place the following outline In your notebook for use In reviewing:

1 r^ 1 . . £ .1 -1 i (0 Mineral matter from rocks.

1 . Lieneral origm or the soil \ /y^ r\ ■ ^^ c i ,.

° ( (z; Urganic matter rrom plants.

2. Soil-forming agents.

fa. Wears the material. (1) Moving water ^ b. Carries the material.

[c. Sorts and deposits the material.

{a. Grinds the material, b. Carries the material, c. Deposits the material.

(3) Heat and cold, especially in the presence of water.

(4) Winds.

(5) Earthworms, ants, and living animals.

(6) Living plants.

(7) Gases in the air and water.

(8) Plants and animals decaying.

Soils, Burkett.

Physics of Agriculture, King.

The Earthworm, Darwin.

The Soil of the Farm, Scott and Morton.

Chapter II Classes Of Soils

Classes of Soils — Generally speaking, the different components of soils are sand, clay, and humus. Soils are known as sandy, clayey, humous, or loamy, according to the amount of each material they contain.

Sandy Soils — When a large part of the soil consists of sand, it is said to be sandy. Sandy soils weigh more than other kinds.* They become warm rapidly; there" fore they can be worked early in the season. They can be cultivated easily, and they admit air and moisture readily. When very sandy, they are poor soils for growing most crops, because:

L They do not contain enough plant food to supply the growing crops.

2. They absorb water rapidly, but they do not retain it; therefore the crops are apt to become dry and parched in times of drouth.

3. Because of their porous character they do not hold fertilizers well. The amount of fertilizer that passes through the soil and is lost depends upon whether the sand is fine or coarse, and whether the sandy top soil

* The terms Light and Heavy, as applied to soils, have nothing whatever to do with their weight. Soils like sand that are easy to work are said to be light. Clay soils are hard to work, and are said to be heavy.

CLASSES OF SOILS 11

has a subsoil of clay or of sand. If the subsoil is clay, the fertilizing materials do not pass through the top soil so readily.

How to Improve Sandy Soils — Humus increases the ability of sandy soils to hold moisture, prevents the leaching of fertilizers, and is beneficial because of the plant food it contains. It can be supplied indirectly by green manuring; that is, by growing such crops as clover or peas and plowing them under; or it may be supplied by applying barnyard manure. Lime increases the moisture-holding capacity of sandy soils by causing the grains of sand to adhere to each other. Clay could be added to help retain the moisture, but its application is usually expensive.

Clay Soils — Pure clay is composed of very fine soil particles packed closely together. Although it holds moisture for a long time, its compact nature prevents moisture and air from moving freely through it. Crops suffer on a soil containing too much clay, both in wet seasons and in dry seasons. In wet weather too much moisture is retained. In dry seasons baking causes the soil to become so hard that the roots of plants cannot penetrate it. Clay soils are difficult to work, because they are sticky when wet and hard when dry.

How to Improve Clay Soils — We have seen that clay soils differ in character from sandy soils. Anything done to make the soil warmer, to cause air and moisture to move freely through it, and to prevent its baking, will result in an improved condition.

The addition of barnyard manure makes clay soils more porous, allowing air and moisture to move freely through them. Green manuring acts in the same way. The addition of lime causes clays to become more friable. All of these methods tend to keep the soil from baking. It should be remembered that the addition of humus will not improve wet clays unless they are properly drained.

Humous Soils — Humus consists of partially decayed plants and animals. It is easily recognized by its dark color. Humous soils hold rather too much moisture, but they are fertile when properly drained. The addition of coarse barnyard manure benefits this class of soils.

Loamy Soils — A loam consists of a mixture of sand, clay, and humus. As these may be mixed in any proportion, there are several kinds of loams. It is convenient to consider three classes of this type of soils; viz., loam, sandy loam, and clay loam. A loam contains about 50 per cent, of sand. A sandy loam consists of more than 60 per cent, of sand. A clay loam contains 30 per cent, of clay, or over. It should be remembered, however, that when a soil contains more than 60 per cent, of sand it is called sandy, and not loamy. In like manner.

CLASSES OF SOILS a soil which is more than half clay is called a clay soil. Loams are good soils for the following reasons:

1 . They contain sand, which renders them warm and causes them to absorb moisture and air freely.

2. They contain clay, which renders them cool and prevents the moisture evaporating too rapidly.

3. They contain humus, which aids in retaining moisture, and, in the process of decomposition, furnishes food for plants.

Limestone or Calcareous Soils contain about 20 per cent, of lime or over. Unless they contain too much lime, they are good soils, especially for raising grains and fruits. Limestone soils are easily worked.

Alkali Soils are found chiefly in the arid regions in the western United States. They are so called because they contain a large amount of salts of various kinds. Such soils are unproductive for most crops until the salts are washed out by irrigation and drainage.

Sugar-producing plants require large quantities of alkali. The growing of such plants on alkali soils is recommended. Sugar beets, sorghum, onions, asparagus, sweet clover, pears, and figs grow well on alkali soils.

The Best Soil for general purposes contains sand, clay, humus, and lime in proper proportions. As few farms contain each of these materials in the right proportion, the farmer has to consider what crops his land is best fitted for, as well as how to improve the condition of the land.

1 . Examine some dry sand, dry clay, and dry humus. Notice the size, shape, and color of the grains in each. Moisten each of these soils and see which can be molded into a definite shape the best. Which soil remains crumbly?

2. Put a couple of handfuls of soil into a glass jar, pour on some water, and shake vigorously. Let the jar stand awhile. The sand settles at the bottom of the jar; some of the clay settles on top of the sand, while some of the finest clay is held in the water, making it look roily; some humus may be seen floating on top of the water. Try this with various soils and estimate the parts that are sand, clay, and humus.

3. Experiment to show how alkali salts gather on the surface of a soil in the form of a crust: Place a handful of salt in the bottom of a glass tumbler, fill the tumbler with sand, pour water on the sand, and set the tumbler aside in the sunshine. What happens when the water evaporates?

4. Experiment to show what portion of the soil is humus and what portion is mineral matter: Dry the soil thoroughly. After it is dry, heat it red-hot over the flames of a fire. The humus will burn. The portion

CLASSES OF SOILS 15

of the soil that does not burn is mineral matter. Test

equal amounts of various soils to see which contains the

most humus in relation to the mineral matter.*

Make an outline of each kind of soil to show the

composition, characteristics, defects, and the ways of

improving each.

REFERENCES Soils, Buikett.

The Soil of the Farm, Scott and Morton. First Principles of Soil Fertility, Vivian. Chemistry of the Farm, Warrington.

Manures: How to Make and How to Use Them, Sempers. The Physical Properties of Soils, McCall.

*The amount of film water is so small that it may be disregarded in this experiment.

Chapter III

Water Necessary for Plant Growth — Plants cannot live without food and water. The water containing soluble plant food is taken from the soil by the plant roots and passes through the plant to the leaves, where a great deal of it evaporates. For every pound of vegetation produced, from 100 to 600 pounds of water are required. The evaporation of the water from the surface of the land is also considerable. The question of water supply m the soil, then, becomes one of great importance.

Kinds of Moisture in the Soil — There are three classes of water in the soil; viz., free water, capillary water, and film or hygroscopic water.

Free Water — The water contained between the soil particles, which would drain away if it had a chance to do so, is called free water, or ground water. A hole dug in soil containing free water will be partly filled up by the free water, and the height to which the water rises in the hole will indicate the height of the free water in the soil. The upper surface of the free water is called the water table. It is the free water which supplies springs and wells.

Capillary Water — If you place one end of a glass tube of small bore and open at both ends in a dish of water, act in the therefore in the soi the water inside the tube will rise above the water level in the dish. The small spaces between the soil particles same way as the space in the tube; the water will pass from space to space Welter level ^Iways moving from a \r\ tube. moist to a dry portion.

Water level t .i • l -ii

in dish. In the same way mk will

rise in a strip of blotting paper, and oil through a lamp-wick. The force which causes liquids to pass through porous substances in this manner is called capillarity, or capillary attraction. Plants depend Fig. 6. Water Rising in Tube ^p^j^ ^\^q capillary Water of the soil

y api ary ttraction ^^^ ^^^^ ^^ ^^^^.^ Water SUpply. YoU

can see the water rise in the soil by capillary attraction if you will perform the following experiment:

Place a lamp chimney on a blotter in a saucer. Fill the chimney with dry soil, and pour some water in the saucer. Observe the water rise through the soil.

Film or Hygroscopic Water is a very thin layer of water around each soil particle. It will pass off as steam if the soil is heated to a high temperature.

Various Uses of Soil Moisture— 1. Some of the food materials cannot be used by growing plants until they are changed by chemical processes. The presence of moisture aids greatly in these chemical processes.

2. Plants cannot take up solid foods, but can take up foods in solution. Water dissolves plant foods.

3. The water carries the dissolved plant foods to the various parts of the plant.

4. Some of the water is used by plants to build up the plant tissues.

5. The water regulates the temperature of the soil.

Capacity of Soils for Moisture — When the spaces between the soil particles are completely filled with water, the air is kept out of the soil; therefore the plants will die — as is commonly said, they drown. When there is a lack of water in the soil, the plants are not only unable to obtain moisture, but their roots cannot obtain the necessary plant food, because the food materials must be taken up in solution.

It is supposed that crops suffer whenever the soil contains more moisture than one-half or less than onefifth of the capacity of the spaces between the soil particles.

What Can Be Done in Case of Too Little Moisture in the Soil — The lack of moisture in the soil is due to one or more of the following conditions:

1. Insufficient rainfall.

2. Too great percolation.

3. Evaporation.

4. Transpiration.

Insufficient Rainfall — By irrigation, crops can be grown where there is little or no rainfall. The various systems of irrigation will be discussed later.

Percolation is the term given to the passing of the free water downward through the soil. It is greatest in coarse-grained soils. There is an immense amount

Fig. 7. Water in the Soil

a, rain water percolating through the soil ; b. water rising by capillarity ; c, evaporation taking place at the surface ; d. evaporation prevented by a mulch

of difference in the percolation of water in coarse-grained soils having coarse-grained subsoils, and in those having fine-grained subsoils. If a sandy soil has a subsoil of clay, the water does not pass downward as rapidly as it would if the subsoil were of sand or gravel. Percolation can be prevented to a certain extent by adding clay, humus, barnyard manure, or by green manuring.

Evaporation not only causes the ground to become dry, but it causes the soil to become cold. For this and other reasons the farmer desires to prevent it as much as possible. Evaporation is greatest when there is a high temperature, when the air is dry, when there are dry winds, and in coarse soils. It can be lessened by adding humus, clay, or manure. Shallow tillage with a fine-toothed cultivator greatly hinders evaporation. In this case the water rises by capillarity until it reaches the loose cultivated soil on top, through which it does not readily pass.

Transpiration — Much of the water taken up by the plant is given off by the leaves. This transpiration of water, as it is called, is large, but varies in various plants. Sunlight and dry weather are conditions which make transpiration rapid.

In some sections of the country there is not enough rainfall to supply a succession of crops with water; hence a system of farming known as dry-farming is followed. This is merely a way of saving moisture that plants would otherwise transpire for the use of future vegetation. In dry farming, plants are grown one year, and the second year the land is allowed to lie idle. Although no crops are raised during the second year, surface tillage is followed in order to save the moisture already in the soil and that which is added by rains during the year. Crops are grown the third year. It will be seen that where this system is followed the rainfall of two or more years can be used for producing one crop.

Too Much Moisture in the Soil — Lands that are low frequently have too much moisture on account of water running on them from higher lands, or the presence of springs, or floods which do not drain off on account of the compact nature of the soil. The only satisfactory way of treating such soils is to drain them.