J sip ee at ep eo or moremenseteyere sates a eet ere seen tast Class Sg Book ee ae Copyright N° COPYRIGHT DEPOSIT, ' AN INTRODUCTION TO AGRICULTURE AN INTRODUCTION AGRICULTURE BY eae A. UP AM TEACHER OF SCIENCE, STATE NORMAL SCHOOL WHITEWATER, WISCONSIN NEW. Y OF DD 2c Pie CON AND. COMPANY 1910 CopyriGutT, 1910, By D. APPLETON AND COMPANY € 0lLA261091 Pik BA CE Tuer author’s thought in preparing this book has been to provide an elementary text on agriculture suit- able for use by children of the seventh and eighth grades, and by pupils of a corresponding advancement in un- graded schools. It is hoped, also, that the book will not be found unsuited to the needs of Reading Circles and of individual students. The author, of course, makes no claim to complete- ness, nor is the book offered as a guide to farming. The effort has been, however, to touch those matters which would be most useful to pupils in our rural schools, and especially to give the underlying theory for many farm processes and practices. It is believed that teachers and students will find the summaries and questions at the end of each chapter especially helpful in reviewing and making definite the information which the chapters contain. One of the most important reasons for teaching agriculture in schools is to prepare pupils to read and understand \ vi PREFACE agricultural literature. Lists of such literature and directions for obtaining it will be found at the end of the book. Acknowledgment is gratefully made for the use of material found in various Farmers’ Bulletins and re- ports, especially those of the United States Department of Agriculture, and of the State Experiment Stations of Wisconsin, Vermont, and Minnesota. The author is also grateful to those whose names appear in connection with various illustrations for the use of the same. A. A. UPHAM. WHITEWATER, Wris., 1910. C@NTENTS CHAPTER PAGES - I. Tur Nature or PLANTS ‘ : : : . 1-9 The Science of Agriculture, 1; The Parts of a Plant, 2; How a Plant Grows, 4; How the Plant Gets Its Food, 5; Conditions of Growth, 7; Plant Food Must Be Usable, 8; Summary, 9; Ques- tions, 9. een SOLime : : d 10-19 The Composition of Soil, 10; Kinds of Soil, Formation of Soil—Rock Weathering, 13; ae Action in Formation, 16; Uses of the Soil to the Plant, 17; Good Farm Soil, 18; Summary, 18; Questions and Problems, 19. Ill. Water IN THE SOIL : ; E : 20-29 The Importance of Water to Plants, 20; The Move- ment of Water in the Soil, rs Amount of Water Used by Different Plants, 22; Effect of Too Little Water in the Soil, 22; Effect of Too Much Water, 22; How the Soil May be Made to Hold More Moisture, 25; The Benefits of Underdrainage, 26; Methods of Drainage, 27; Summary, 28; Ques- tions and Problems, 29. IV. TrimimNeG tHe Som . : . l 30-39 Tillage, 30; Objects of Tillage, 30; ihepivetion of the Seed Bed, 32; Regulation of Moisture, 32; Other Uses, 33; A Risk in Tilling, 33; Importance of Good Tillage, 34; Tillage Implements—The Plow, 34; Harrows, Plankers, and Rollers, 35; Dry vil Viil CHAPTER Ve vid. VET. VIE. CONTENTS PAGES Farming, 37; Summary, 38; Questions and Prob- lems, 38. ENRICHING THE SOIL ; ; \ ; : 40-53 Elements and Compounds, 40; The Source of the Three Kinds of Plant Foods, 42; How These Foods Get Into the Plant, 43; The Use to the Plant of Each Kind of Food, 45; Barnyard Manure, 46; Other Ways of Enriching the Soil, 48; Commercial Fertilizers, 48; Amendments, 49; Nitrification, 50; Summary, 51; Questions and Problems, 52. LreGuMINoUS PLANTS AND RoTATION oF Crops 54-62 Clover and Its Relatives, 54; Fixation of Nitrogen, 55; Legumes as Nitrogen Gatherers, 55; Other Uses of Legumes, 56; Rotation of Crops, 57; Rota- tion Is a Weapon Against Pests, 57; Rotation Destroys Weeds, 58; Rotation Practically Enlarges the Farm, 58; Rotation Regulates the Food Sup- ply in the Soil, 59; The Norfolk System of Rota- tion, 60; Summary, 61; Questions, 62. Tue Uses THE PLANT Makes or Its Foop 63-70 The Factory of Nature, 63; Oxygen, Hydrogen, and Carbon, 63; The Products of Plant Growth, 64; How the Plant Digests Its Food Elements, 66; Changing Starch to Sugar, 66; Changing Sugar to Starch, 67; The Composition of Certain Vegetable Products, 68; The Production of Heat, 68; The Production of Seeds, 69; Summary, 69; Questions and Problems, 70. Piant Enemies: Weeps, INSEcTs, AND PLANT DISEASES. . : ; ‘ ; : : 71-89 What a Weed Is, 71; Why Weeds Are Enemies, 71; Classes of Weeds, 72; Annuals, and How to Kill Them, 72; Biennials, and How to Kill Them, 75; Perennials, and How to Kill Them, 75; Descrip- tion of an Insect, 77; Life History of Insects, 78; CHAPTER IX. Tue FARMER’s Frrenps: Birps, Toaps, Insects 90-102 X. PROPAGATION OF PLANTS BY SEEDS XI. XII. XIII. Farm Crops CONTENTS Classification of Insects, 79; Some Common Cut- ting Insects, 80; Some Common Sucking Insects, 83; Insect Control, 84; Nature of Plant Diseases, 85; Some Common Diseases and Their Treatment, 85; Summary, 88; Questions, 89. Birds and Their Food, 90; Useful Birds, 91; At- tracting the Birds, 96; Toads and Frogs, 99; Useful Insects, 99; Summary, 101; Questions and Prob- lems, 101. Seeds, 103; Flowers, 103; The Parts of a Flower, 103; Pollination, 106; Cross Pollination and Hybrids, 107; Propagation of Plants, 108; Quality of Seeds, 109; Age of Seeds, 109; Maturity of Seeds, 110: Selecting Seeds, 110; Testing Seeds, 115; Conditions Affecting Germination, 116; Sum- mary, 117; Questions and Problems, 118. PROPAGATION BY CUTTINGS AND OTHER MEANS ; : : . 119-126 Other Methods of Bie iaton: 119; Growth from Buds, 119; Cuttings, 120; Layering, 121; Grafting, 121; The Necessity for Grafting, 124; Budding, 125; Summary, 126; Questions, 126. Tue Farm GARDEN . : . 127-13 The Importance of the Farm Gees, 127; Position and Soil for the Garden, 127; The Care of the Garden, 128; Desirable Plants fcr the Garden, 128; Summary, 131. Hay and Grass Crop, 133; Alfalfa, 134; Clovers, 135; Corn, 135; Wheat and Other Grains, 137; Field Peas, 141; Potatoes, 141; Root Crops, 142; Cotton, 143; Sugar Cane, 145: Rice, 146; Tobacco, 146; Summary, 149; Questions and Problems, 149. 103-118 133-149 xX CHAPTER XIV. XVI. mov iL, XVIII. CONTENTS PAGES THe ORCHARD. ; : ; bi ite . 150-158 Apples, 150; Pears, 152; Peaches, 153; Cherries and Grapes, 154; Merkotine Fruit, 154; Transplant- ing and Pruning, 154; Summary, 158; Questions and Problems, 158. JATTLE : 3 ; . 159-169 The Usefulness of the Cow, 59; The Dairy Cow, 159; Beef Breeds, 164; pe eithas in Raising Cattle, 166; The Importance of Good Cattle, 167; How to Improve the Herd, 167; Summary, 168; Questions and Problems, 168 MiLk AND Irs Propucts : : : . 170-180 . The Composition of Milk, 170; The Food Value of Milk, 172; The Souring of Milk, 172; The Milk Tester, 174; The Separator, 174; Cream, 176; Skimmed Milk, 177; Butter, 177; Cheese, 178; Summary, 179; Questions and Problems, 180. THe Horse : i sy ts Se Antecedents and Types: 1st. Dadrable Character- _ istics, 181; Speed Horses, 183: Draft Horses, 185; Coach Horses, 187; Ponies, 187; Use and Care of Horses, 188; The Intelligence of Horses, 189; Summary, 190; Questions, 190. SHEEP AND SwINE . : : ‘ . . 191-201 © Advantages of Sheep Rae 191; Breeds of Sheep, 191; Advantages of Raising eae 194; Breeds of Swine, 195; Where and How to Raise Swine, 198; Summary, 199; Problems, 200. PouLTRY AND BEES : : . 202-213 Benefits of Poultry anne 202: Breeds of Chickens, 204; Ducks, Geese, and Paieese. 207; Raising and Care of Poultry, 207; Summary, 212; Questions and Problems, 212. PRINCIPLES OF FEEDING AND CARE OF ANIMALS 214-225 Importance of Animal Food, 214; Classes of Feeds, 216; Balanced Rations and the Nutritive Ratio, CHAPTER CONTENTS 217; Kinds of Feeding Stuffs, 220; Profit and Loss in Feeding, 222; Care of Animals, 223; Sum- mary, 225; Questions, 225. XXI. Goop Roaps.—ForEestry.—HoME AND ScHoon GROUNDS . : 3 : . 226-241 INSECTICIDES AND FUNGICIDES TABLES REFERENCES The Farmer’s Interest in ened Roads, 226; How to Make and Keep a Road Good, 226; The Burnes of Forestry, 229; Some Advantages of Forests, 230; What Other Nations are Doing in Forestry, 231; What Our Government is Doing, 232; How a Forest May be Perpetuated, 233; Home and School Grounds, 234; Trees and Shrubs, 234; Vines, 236; Flower Garden, 237; Hardy Perennials for the Farmer’s Flower Garden, 239; Hardy Flowering Shrubs Best Adapted to the Farmer’s Garden and Lawn, 239; Conclusion, 240; Summary, 240. APPENDIX Bordeaux Mixture for Blights, 243: How to Treat Seed Oats to Prevent Smut, 244; How to Treat Seabby Seed Potatoes, 245; Kerosene Emulsion, 245; Paris Green, 245. xl PAGES 243-246 246-259 Table Ie ao Constituents Gantanad's in Average Crops per Acre, 246; Table II.—Fertility Removed by Different Crops 246; Table III.—Space and Quantities of Seed Required, 247; Quantities of Seed Required to the Acre, 247; Table IV.— Amount of Nutrients for a Day’s Feeding, 248; Table V.—Dry Matter and Digestible Food In- gredients in 100 Pounds of Feeding Stuffs, 250 Fuel Value, 252; Table VI.—Rations Actually Fed to Horses and Digestible Nutrients and Energy in Rations, 253; Table VII.—Pounds of Total Dry Matter a Digestible Ingredients (Protein and Carbohydrates, Including Fats x 25) in Varying Weights of Fodders and Feeds, 254 259-261 AN INTRODUCTION TO AGRICULTURE CHAPTER I THE NATURE OF PLANTS 1. The Science of Agriculture.—Agriculture or farm- ing consists primarily in raising plants and animals. The farmer aiming to have a profitable business must under- stand many things about the plants and animals he raises, for without a knowledge of their.nature, their habits, and their needs he may labor year after year making only a halfway success of his work. It is easy to waste the good things that Nature has provided for the farmer. It is easy also to increase greatly the or- dinary production from the land—if one only knows how. How to get the best results in agriculture is a ques- tion that men are studying all the time. Agriculture is a science—one of the most useful of all the sciences. Wherever agricultural science improves farming it bene- fits mankind. Human beings everywhere are depend- ent on farming for food. This food in great variety comes from plants and from animals. Animals them- selves are dependent on plant growths for food. So we see that the growing of plants by farmers is one of the fundamental occupations of human kind. The farmer, first of all, should be interested in study- ing the fundamental facts of his science. He must 1 2 AN INTRODUCTION TO AGRICULTURE understand how plants grow and what kinds of soil are best suited to the growth of the various plants. He must have a scientific knowledge of the diseases and the enemies of plants and how to overcome them. He will wish to know also many facts about cattle, poultry, sheep, and other farm animals. Such fundamental facts we are to study in this book. 2. The Parts of a Plant.—In speaking of plants now we are thinking of all kinds of things growing out of the earth that provide food—trees, grains, grasses, vines, roots, and all the others. Most plants have roots, stems, leaves, flowers, and fruits or seeds. Some of the lower plants, which are used for food, such as mushrooms, do not have all of these parts. Some are dependent on other plants for their support and for theirnourishment. These parts or organs are concerned with the two functions of \ ia a sy plants—growth and_ repro- TER oD. oan duction. The growth organs yt Aris x4 are the roots, stem, and yi i Nex leaves; the reproductive or- | (i gans are the flowers, fruits, and seeds. Roots.—The roots reach out through the soil, hold- TypicAL PLant (COLUMBINE). ; ; Showing a, flower; b, leaf; c, ins the plant m place and stem; d, roots. gathering food for it. They THE NATURE OF PLANTS 3 arise from the stem, and branch or divide into smaller roots, until they become fine, delicate rootlets. Except at their tips, the tiny rootlets are covered with still finer root hairs. These root hairs take in food for the plant. They may increase the absorptive or feeding surface of the root seven to seventy-five times. Stems and Leaves.—The stem is the supporting organ, the framework on which the leaves and flowers are borne. It may be very short and thick as the ‘‘crown”’ of turnips and beets; it may be very slender and light as in the grains and grasses; or it may be large and strong GOOSEBERRY. Showing a, flower; b, fruit; c, seeds. as in the trunks of trees. The food absorbed by the root hairs passes through the larger roots and the stem to all parts of the plant. On the stem and generally in the axil of a leaf, buds are borne which produce branches bearing either leaves or flowers. The leaves help gather food by absorbing gases from the air. And it is in the leaves that the food elements gathered by the roots and leaves are made ready for the use of the plant. 4 AN INTRODUCTION TO AGRICULTURE Place the stem of a plant (balsam) in water colored with red ink and watch the passage of the water up the stem and into the leaves. Flowers, Fruits, and Seeds.—The flowers on a plant produce the fruit and seeds. The seed, as you know, contains the young plant. The parent plant stores food in the seed, and this food the young plant uses in send- ing out its first shoots and getting ready to glean its own living. Lima Brean. a, cotyledons opened to show hypocotyl and plumule; b to e, successive stages in germination showing development of hypocotyl, roots, cotyledons, stem, and plumule. 3. How a Plant Grows.—You may have seen how a plant begins to grow from the seed. It sends a shoot upward toward the light and another shoot downward as a root. The upward shoot becomes the stem. It branches out and has leaves, and so makes the full- grown plant which we see. The root, as it grows, also divides into many branches which run through the ground, THE NATURE OF PLANTS 5 If you put some beans or other large seeds in water or damp sand, you can see how they sprout. On the outside will be found two coatings. Beneath these are two leaves, thick and yellow. They contain the nour- ishment on which the young plant begins its life. These leaves are called cotyledons. Place some large seeds, such as beans or peas, in water over night. Then take out some of them and study their structure. Place the others in damp sawdust or sand. Continue for sev- eral days the study of the little plants. Lay the first leaves apart and you will find between them two tiny leaves supported by a minute stem. These inner leaves are called the plumule and the stem is called the hypocotyl. The hypocotyl grows and lifts the leaves above the ground. From the hypocoty! also the first root starts in its downward growth. In some plants the plumule develops into the first real leaves; in others the cotyledons become the first leaves above ground. Corn and certain other seeds have only one cotyledon. 4. How the Plant Gets Its Food.—The plant starts its life by feeding on the food stored in the seed. But as soon as its leaves have reached the sunlight and its roots begin to spread out through the soil, the plant must find and make its own food. Air, water, and mineral salts _ in the soil are the plant’s food materials. Sprout grains of corn, wheat, barley, etc., between two pieces of damp cloth inclosed between two plates. Place two or three matches with the seeds to prevent mold, and set the plates in a warm place. In a few days study the seedlings, ex- 6 AN INTRODUCTION TO AGRICULTURE amining the parts. Notice the hairs on the roots. Compare the different kinds of plants. The plant can take in nothing in solid form. All its food from the soil comes to it dissolved in water, which can pass readily from the soil through the root hairs into the tiny rootlets. The soil water contains carbonic acid derived principally from decaying organic matter which helps it to dissolve the mineral compounds in the soil. The water passing into the root hairs takes with it the mineral salts that are necessary to the plant’s health and growth. These min- eral salts are really several substances mixed together, but all are called salts. While the salts are Cross Section or a Roor Suowmsa tHE lissolved in water, Roor Harrs. a, bark cells; b, duct for passage of Grater we cannot see them. Their tiny invisible particles are mixed with the particles of water in what is known as a solution. If we boil some water until it has all evaporated, we shall generally find in the bottom of the kettle a white substance that looks like common salt. This is the mineral salt which was in the water but which did not evaporate with it. When we burn plants the mineral parts are left in the form of ashes. The plant feeds from the air as well as from the water in the soil. Its leaves absorb gases from the air, and these gases, especially the carbon dioxide, are used THE NATURE OF PLANTS 7 in preparing the food for the plant. In some way that we do not wholly understand, a plant has the power to combine the water, the mineral substances from the soil, and the gases from the air so as to make food for itself. This can take place only in sunlight. In this process the leaves return to the air through the stomata a gas which we call oxygen and more or less water. - 5. Conditions of Growth.—In order to grow well, the plant must have the proper conditions of heat, water, air, light, and food. Until the weather is warm ‘most plants do not even sprout. UnperSiprorLear. Show- Light is very essential to the life Ls ay lis Sea of plants; in the dark they stop B, a cross section show- growing or grow only a little te eae cece and weakly. :212 4 cao SO rc Gre@Nn: 8786855 At. oe oe eee 85 43 But the plant actually needs much more water than is shown by such a table. To keep healthy, a plant must constantly have a great quantity of water passing through its stems or branches to the leaves. The water evaporates from the leaves into the air. Experiments have shown that, for each pound of dry grain to be harvested, three hundred to five hundred pounds of water should pass through the plants producing the erain. : 16. Effect of Too Little Water in the Soil.—A plant will quickly starve if it has not enough water. Water itself is the most important plant food, and it is the medium for the transmission of plant food, for the plant gets its mineral food in the water which its roots absorb. Herbs and other plants that have little woody tissue in their stems wilt and droop if they have not sufficient water. The water is needed to fill out the stems and keep the plants stiff and upright, as well as to bring food from the soil. 17. Effect of Too Much Water.—Plants may suffer from too much water in the soil as well as from too little. WATER IN THE SOIL 23 Air is needed in the soil in order that the plant may get its proper food (Sec. 5). If the soil is very wet, so that water fills all the spaces among the grains of soil, there will be no room for the air. You may understand better how the soil holds both air and water if you think of a wet sponge. The substance of the sponge holds water, and all through the sponge are tiny open spaces, or pores, filled with air. Too much water may injure the plant in another way. The roots of most plants will not go down into water. If they find the ground too wet, they will spread out near the surface instead of going deeper. Later, when the weather becomes hot, the roots, being near the sur- face, will dry up. Too much water at first results in too little available water later. Still another thing we must remember about water- soaked soil. Ground that is very wet is cold. More heat is required to warm water than to warm soil. Then, too, from wet ground water is all the time evaporating. As it passes off into the air, the water takes with it some of the warmth in the ground. This warmth is needed for the growth of plants, and especially of seeds. Rapid evaporation from wet soil wastes it. When the sun is warming the land in spring, wet soil is not made ready for seed planting so soon as soil with only a moderate amount of moisture. A wet soil is likely to be over- acid or sour, and not well suited for crop growth. Thus we see that for many reasons it is important that the soil for most plants should not be water-soaked. The soil is a storehouse for water. One of the chief problems of the farmer is how to regulate the sup- 24 AN INTRODUCTION TO AGRICULTURE ply and give his crops neither too little nor too much water. For this and some other experiments a small spring balance weighing by ounces up to four pounds is desirable. Provide five pint bottles with the bottoms cut off as follows: To cut off the bottoms of the bottles, saturate a string with kerosene or alcohol; let it drain and then wind it two or three times around the bottle near the bottom. Tie the string tightly and cut off the ends. Light the kerosene and let it burn, hold- ing the bottle bottom upward. As soon as the kerosene is nearly or quite done burning, dip the bottom of the bottle into water, if the bottom has not already cracked off. Cork the bot- tles with corks having notches cut in the sides so as to allow water to enter when the necks are immersed in water. Tie a string around the neck of each inverted bottle and bring the string up near the bottom of the bottle so as to make a noose around the bottle. Make a loop in the end of the string into which the hook of the balance may be placed. Weigh each bottle, and record the weight. Place in each bottle a pound (or other known weight) of some kind of soil, as, for example, gravel in one, sand in another, poor soil in the third, loam in the fourth, and leaf mold in the fifth. Stand the bottles bottom up in old tin cans, each can containing the same amount EXxrrRment SHowina Ansorp- Of water. Cover the open ends of TION oF Water By Sous. — the bottles with a piece of rubber sheeting to prevent evaporation. After two or three days weigh each bottle to see which soil has gained the largest amount of water. Empty the remaining water from the cans, replace the bot- WATER IN THE SOIL 25 tles, and uncover the ends to allow the water to evaporate from the soil. Note which kind of soil loses water rapidly. 18. How the Soil May Be Made to Hold More Moisture. —Let us see what the farmer can do to make the soil hold more moisture. You will remember that water in the soil finds its place in the minute spaces between the particles of soil (Sec. 6); and you have learned that by capillary attraction the water creeps up along the sur- faces of these particles of soil (Sec. 14). By breaking up the soil into finer pieces the farmer may increase the total surface and also the total space for the water to fill. This will be clear if you think of cutting a cube of cheese into pieces. If the cube is one inch square, its surface contains six square inches. By three cuts with a knife the inch cube can be made into eight half- inch cubes. The surface of these eight cubes to- gether is twice that of the inch cube. The inch cube y X EXPERIMENT SHOWING INCREASE OF offered no space into which CEG RO PS eek SEr a liquid could be poured, but the eight smaller cubes thrown together offer many little cracks and crevices. ‘This illustrates why the farmer should make his soil fine by tilling, the meth- ods of which we shall study in the next chapter. The soil is made more porous and able to hold more moisture, without becoming cold or soggy, by adding humus (Sec. 7) to it. Barnyard manure or plowed- under crops, of which we shall learn in Sections 35 and 26 AN INTRODUCTION TO AGRICULTURE 36, increase the humus in the soil. Humus can hold more than seven times as much water as the same amount of sand (reckoned by weight) can hold. A little humus mixed with soil increases the ability of the soil to hold water to a degree equal to nearly twice the weight of the humus. Get three examples of garden soil, one from a depth of six inches, one from a depth of twelve inches, and one from a depth of eighteen inches. Weigh as accurately as possible eight ounces of each and thoroughly dry each sample in a warm place. Weigh each dried sample. Divide the loss in weight by the original weight, to find the percentage of water that each contained. 19. The Benefits of Underdrainage.—The best way to regulate the amount of moisture in the soil is by drainage. Farmers have various methods of draining land, that is, of carrying off the superfluous water that falls or seeps into the ground. From ‘what you have just read (See. 17) about the effect of too much water in the soil, you will understand some of the benefits of drainage. If the water is carried off, there is more room for air in the soil. The roots will grow deeper. The soil will be warmer. Excess soluble substances in the soil, which may be injurious to crop growth, will be removed and the soil will really provide more available moisture during the season. The fact that in drained land the roots can go deeper is beneficial in several ways. These roots will feed in the deeper soil and will take less water from the surface. So long as the water is not drawn from the surface layer of soil, the moisture below will not rise by the force of WATER IN THE SOIL 27 eapillarity (Sec. 14). It will be stored up until needed. Later in the season when a dry time comes, this store of water will rise toward the surface as the moisture there evaporates. Thus you see that drainage improves the condition of the soil in such a way as to increase its capacity to hold available water without the evils that attend the presence of superfluous water. Deep-growing roots also open up places for the air to penetrate farther into the soil. As underground water is drained off, clay in the soil shrinks and cracks, and these cracks offer another means by which air gets into the soil. It is important to provide drainage for a clayey soil; for a sandy soil this generally is not necessary. | When land is drained, the water from rains can sink into the ground. Otherwise the rains may wash away the surface soil and i injure plants. 20. Methods of Drainage.—The best method of underdrainage is by trenches, with hollow tiles at the , pe Law) o ce | rn su i ith eS Sree SSS = 5 wv vi cen ha nv 7 ii seen aye i( ne mati vi i Sia Mili hfe 7 ih = “SS A Tite Drain. bottom. The trench is dug two and one half feet to four feet deep. The tiles are one foot long or more and two to eight inches in diameter. They are placed end 28 AN INTRODUCTION TO AGRICULTURE to end, without cementing, on a gradual grade, and the trench is filled with earth. The water from the soil gets into the tiles through the small spaces where the ends join and flows through the pipe of hollow tiling. The rows of tiles are placed through the field at distances apart varying from thirty to one hundred feet. Some- times stones are used instead of tiles. They are laid in the ditch so as to form a channel for the water. Farmers sometimes drain their land by open ditches, but it is hard to work a field cut up in this way. When such ditches must be had, it is best, if possible, to make them so broad and gently sloping as to permit their being kept in grass and readily mowed with a machine. Sometimes the ditches are filled with stones or brush, and it is then more difficult to keep the weeds down. Such an arrangement is much less satisfactory than tile drains, which are less expensive to keep up, are more permanent, more effective, leave no obstructions on the surface, and waste no land. SUMMARY Water exists in the soil as free water and film water.—Water moves through the porous soil by the force of capillarity.—Dif- ferent crops use 300 to 500 pounds of water to produce one pound of dry matter.—The water serves the plant as food, to carry food, and to render the plant stiff and rigid.—Too little water robs the plant of its food and allows it to wither.—Too much water in the soil injures the plant by keeping air out of the soil, by preventing the roots from penetrating the soil, and by making the soil cold. The moisture-holding capacity of the soil may be increased _ by tilling, by adding humus, and by drainage.—Underdrainage WATER IN THE SOIL 29 allows the plant to root deeply, opens up the soil for the ad- mission of air, deepens the feeding ground of the plant, increases the capacity of the soil to hold water, and lessens washing by rains. Draining by tiles is the best method of underdrainage. QUESTIONS AND PROBLEMS 1. What kind of soil allows the free water to pass through most readily? 2. Give illustrations of capillarity, or capillary attraction. 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? (Sec. 16.) 5. Can every piece of land be drained? What conditions are necessary in order that it may be drained? 6. It is said that wheat uses 453 pounds of water to produce one pound of dry matter. At 30 bushels to the acre (60 pounds per bushel), how many tons of water per acre would be required? 7- One inch of water over an acre weighs nearly 100 tons. Can you find what is the weight of the annual rainfall in your vicinity? How many inches would be necessary for the number of tons found in Question 6? The wheat straw will weigh one and one half times as much as the grain. How much water will it require? 8. Why will a crop on well-drained land have more time to mature than on undrained land? 9. If a cube an inch on each side is divided into cubes one eighth of an inch on each side, how many cubes will there be? 10. How many times as much surface will the little cubes have? CHAPTER IV TILLING THE SOIL 21. Tillage.—Tilling the soil is one of the means by which farmers improve their land. Plowing partly in- verts the soil and grinds the particles together. Culti- vation stirs and loosens the surface soil and thereby makes it finer. These operations change the texture of the soil, as we say. When an entire field is tilled, the operation is called general tillage. This is done usually to prepare the soil for the planting of seeds or to mix with the soil manure that has been spread over the surface. Sometimes after the plants have come up the soil is tilled between the rows of plants. This is called inier- tillage. In its larger sense the word cultivation means the same as tillage. More narrowly, it means the use of the cultivator to stir the surface soil. 22. Objects of Tillage.—Briefly, the object of tillage is to put the soil in such a physical condition that it makes an ideal home for plant roots. There are many reasons why plants need a loose, fine soil. If the soil is in lumps, the tiny roots cannot enter it easily, and it will neither support the plant nor give it food. Tillage 30 PLOWING WITH A FouR-HORSE TEAM ON A RANCH IN OKLAHOMA. SreAM PLow AND SEEDER AT WoRK ON A RANCH IN CALIFORNIA. ol 32 AN INTRODUCTION TO AGRICULTURE gives depth of soil so that there is ample living room, a large feeding area, an abundant storage for moisture, and available plant food. A lumpy soil and a hard crust covering the surface will keep out the air, which is neces- sary to soil activities. We learned in the last chapter (Sec. 18) that a fine soil gives more room for water among the particles of earth. In a fine soil this moisture can circulate better and tillage is a great help to certain very important soil organisms that make plant food available, which we have not spoken about yet. 23. Preparation of the Seed Bed.—Seeds especially require a good soil for their growth, and tillage helps to prepare the proper seed bed. In the spring the soil is turned over so that the sun may warm it and is har- rowed down into a fine smooth bed. The soil must be fine and loose, so that when the seed sprouts its delicate stems and rootlets may easily get through the soil and close to the soil particles. In some cases it is desirable to till the ground just before the young shoots come up, » so as to break the crust for them. 24. Regulation of Moisture.—Tillage helps to regulate the amount and movement of moisture in the soil. When a few inches of the surface soil have been loosened, the rain water will sink in instead of washing off the land and being wasted. This loose soil on top makes what is called a sur- face mulch. In loose earth the particles of soil are more separated, so that there is more space between them, Water does not readily pass through dry, loose soil by ceapillarity, for, in the loose soil, the capillary pores are broken up. So this surface mulch prevents the ground TILLING THE SOIL 33 from drying out by making it impossible for the deeper- lying moisture to reach the surface. When possible, the land should be tilled after each rain to keep the soil loose. By repeating this so that two or three inches of soil on top are always loose and dry, the farmer can keep most crops alive even in the driest weather. Tillage, then, accomplishes two im- portant things: it carries rain water to the roots, and it prevents moisture stored deep in the soil from coming to the surface and evaporating. 25. Other Uses.—Soil is often tilled to cover barn- yard manure and green manures, that is, green crops intended to be mixed with the soil to form humus. These are all plowed under so that they may decay and enrich the soil. They provide valuable food for the plant and in many ways improve the physical condition of the soil. Still another use of tillage, and one that farmers count of much importance, is the destruction of weeds. The plow, or cultivator, uprooting them, hinders their growth. The best time to kill weeds is just as they come up, and before they are large enough to do any damage. 26. A Risk in Tilling.—In tilling between the rows of growing crops, great care must be used not to disturb the roots. Corn and some other plants send their roots out between the rows and near the surface of the ground. While tillage is very beneficial to the corn crop, which needs plenty of moisture, the farmer must watch that the cultivator does not go deep enough to break the fine roots. 34 AN INTRODUCTION TO AGRICULTURE 27. Importance of Good Tillage.—It is evident that one of the most important things for the farmer to con- sider is the tillage of his soil. Even though there may be plenty of plant food in the soil and plenty of water and sunshine, all these will not produce a good crop unless the texture of the soil is right. This is obtained chiefly by good tillage. Moreover, a lack of the proper amount of plant food, water, and air may be largely remedied by tillage. 1. Raise plants in two boxes of soil; let the soil in one box be undisturbed and keep the other thoroughly tilled. See whether one plant thrives better than the other. 2. Raise a plant in a porous flowerpot and another in a tin ean. Otherwise treat them just alike and note whether one thrives better than the other. In 1731 Jethro Tull, in England, discovered the value of tilling the soil. He learned that he could get better crops by thorough tillage. Knowing that the plants got more food in this way, he thought that plants took in fine particles of soil as food. He wrote a book to show the value of tilling the soil for this purpose, and though his reasons were wrong he did much good by showing farmers everywhere the value of tillage. 28. Tillage Implements—The Plow.—The most im- portant tools used in tillage are the plow, harrow, planker, roller, rake, and hoe. The plow is the most important tool. Its work lays the foundation for the use of the other tillage tools. It consists of a standard to which the other parts are at- tached, the beam, by which it is drawn; the share, which cuts the furrow slice at the bottom; the mold board, TILLING THE SOIL 39 which turns and pulverizes the furrow slice; the land- side, and the handles, by which the plow is held. Be- sides these chief parts are the clevis, by which the plow is attached to the doubletree, and the coulter, which is sometimes used to cut the furrow slice.