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