i i ' THE MANAGEMENT OF THE SOIL JACKSON AND OAUGHERTY i?tatt College of Agriculture ^t Cornell Mnibetsitg Stijaca. ia. g. Hibrar? Cornell University Library S 591.J13 The management 01 the soil B Cornell University W Library The original of tliis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924000887624 THE MANAGEMENT OF THE SOIL Fhanklin Hiram King A SERIES OF SHORT COURSES IN AORICULTURE COURSE I The Management of the Soil C. R. JACKSON Professor of Agriculture^ State Normal School, Albion, Idaho, and joint author of *^ Agriculture Through the Laboratory and School Garden.'^ MRS. L. S. DAUGHERTY Joint author of **' Agriculture Through the Laboratory and. School Garden" and author (with L. S. Daugherty) of ^^PHnciples of Economic Zoology.''^ OF A THE TRADES THAT I DO KEN, COMMEND ME TO THE PLOXTGHMAN." JACKSON & DAUGHERTY ALBION, IDAHO CAMERON, MISSOURI Copyright, 1918 Br C. R. Jackson PREFACE Years of experience have forced us to the conclu- sion that it is a mistake to try to teach "General Agricul- ture" in the time allotted to it in most secondary schools. General Agriculture is as broad as the earth and as difficult to understand by the average student. The time would be much more profitably spent in the study of a few of the most important phases of Agriculture. It is in the hope of helping to make this plan feasible that we present this "Series of Short Courses in Agri- culture," of which the "Management of the Soil" is the first. The soil is the source of all agricultiu-al products. To his knowledge of it and its management the farmer must owe much of his success. It is important then, that the principles underlying soil management should be given a definite and thorough study at the beginning of the course in Agriculture. It has been our aim to set forth the essential principles of the management of the soil in such a manner that the student may grasp them at the outset. It is intended that the students shall carefully work out the experiments and problems for themselves, especially those adapted to the region in which the school is located. Such work will mean infinitely more than lectures by the teacher and will be much longer remembered. We know that there are different opinions upon some of these topics, but we have tried to give only those con- clusions verified by experience or supported by authorities which are among the best. We are indebted to Dr. John A. Widtsoe, president of the University of Utah, and a widely known authority on agriculture in the irrigated and the dry-farming regions of the West, for the reading of the manuscript, and for helpful suggestions. vi PREFACE We wish also to acknowledge our obligations to the Agricultural Experiment Stations of Minnesota, Missouri, North Carolina, Ohio, Utah and Wisconsin, to the United States Department of Agriculture, to the Jeffrey Manu- facturing Co., to the Janesville Machine Co., and to the Dunham Co. for the use of illustrations. The Authors. CONTENTS THE SOIL Man's Dependence Upon It 1 Exercise 1 : Showing Man's Dependence 1 FORMATION OF SOIL Water as a Factor in Soil Formation 2 Rain 3 Exercise 2 3 Glaciers 4 Temperature 5 Chemical Action 5 Wind 5 Organic Agencies 6 Plants 6 Animals 7 Organic Formations 7 Field Trip 7 AGRICULTURAL TYPES OF SOILS Sandy Soils 9 Clay Soils 9 Loam 10 Structure of Soil 10 IMPORTANCE OF WATER Water Given Off by a Plant 13 Experiment 1 13 viii CONTENTS Water Constitutes Plant-Food 13 Exercise 3 13 Water in the Soil 13 Gravitational Water 13 Capillary Water 14 Experiment 2. To Show Capillary Action 14 Experiment 3. Effect of Texture on Rise of Water 14 Experiment 4. EflEect of Texture on Water-holding Capacity 15 Temperature of the Soil 15 Exercise 4. Effect of Moisture on Temperature . . 16 Exercise 5. Effect of Slope on Temperature 17 SOIL MANAGEMENT Drainage 19 Need of Drainage 20 Effects of Drainage 21 Drainage increases the water-supply of plants . 21 Drainage increases the temperature 22 Drainage improves soil- ventilation 22 Drainage favors desirable soil organisms 23 Drainage prevents erosion and conserves soil fertility 23 Drainage reduces the process of heaving 23 Drainage removes the excess of alkali 23 Experiment 5. Effects of no Drainage 24 Drainage gives permanent results 25 Experiment 6. Effects of Drainage 25 Tjrpes of Drainage 26 Surface Drains 26 Tile Drains 26 Tillage 28 Effects of Tillage 28 Tillage prepares the seed-bed 28 CONTENTS ix It increases and conserves soil moisture 28 Tillage destroys weeds 29 It incorporates crop-residues into the soil 29 Kinds of Tillage 29 Plowing 30 Rolling 34 Disking 35 Harrowing 35 Cultivating 36 Experiment 7. Effect of Humus and Soil Mulch on Conservation of Moisture 37 Irrigation 37 Conditions Necessary 37 Exercise 6 38 Time for Irrigation 39 The Supply of Water 40 Preparation for Irrigation 41 Systems of Irrigation 42 The Flooding System 42 The Furrow System 43 Experiment 8: To Show Capillary Movement of Water 44 Dry Farming .....' 45 Selection of Farm 45 Home . 46 Rainfall , 46 Climate . 46 Soil 46 Equipment for Dry-farming 48 Breaking the Sod 49 Tilling the Soil 50 Cropping the Dry-farm 51 Supplementary Irrigation 52 X CONTENTS FACTORS OF SOIL FERTILITY Essentials of Plant-food 55 Food Elements Derived from Air and Water 55 Carbon 55 Hydrogen 56 Oxygen 56 Food Elements Derived from the Soil 56 Phosphorus 56 Potassium 59 Nitrogen 61 Commercial Fertilizers 63 Home Mixing of Fertilizers 63 Acid in Soils 63 Exercise 7. Litmus Test for Acid 65 Lime for Acid Soils 65 Farm Manures 67 Selection . of Fertilizers 70 ILLUSTRATIONS Franklin Hiram King, Late Professor of Soils, Madison, Wis- consin Frontispiece From the Soil are Obtained Products of the Farm xii Erosion of Rock 2 Trees Protecting the Slope 4 Roots Disintegrating Rocks 5 Vegetation Protecting Wisconsin Hills 6 Tin Cans Prepared for Flower Pots 12 Apparatus for Experiment 3 15 A Four-compartment Soil Bin 16 The Sun's Rays on a Northern and a Southern Slope 17 Tile Drainage Increases Barley Yield . .*. 19 Undrained Land, State Test Farm, Willard, N. C 20 Cowpeas and Corn on the Same Land as in Fig. 11 21 Effect of Tile Drainage on Growing Crops 22 Diagram Showing Typical Reclamation of Alkali Lands 24 Drain Properly Laid to Carry off Seepage 24 Land Reclaimed by Drainage 25 Laying a Tile Drain 26 Arrangement of Drains 27 A 4x6-inch Y-Tile 28 Conserving Moisture 29 An Open Rough Surface 31 Wasting and Compacting of Fall-plowed Land 32 Compacting and Mulching with a Corrugated Roller 33 Mulching with a Disk 34 Spike Tooth Harrow 35 Mulching with a Two-row Cultivator 36 Soil Auger 38 Alkali Spot in a Field 39 Bog Produced by Over-irrigation 40 Fresno Grader — Grading New Land for Irrigation 41 Effect of Irrigation without Cultivation 43 Preparing the Seed Bed for Alfalfa 44 Soil Containing Gravel Streaks 47 Advantage of Adding Phosphate to Manure 59 Common Weeds which Indicate Soil Acidity 64 Lime Spreader 66 Manure Versus no Manure 67 The Results of Proper Care of Stable Manure 68 Manure Loader — True Conservation 69 Manure Spreader 70 xi Fig. 1 THE MANAGEMENT OF THE SOIL THE SOIL "National strength lies very near the soil." — Daniel Webster. Man is dependent upon the soil for his subsistence. All his vegetable food is the direct product of the soil, while meat, eggs, and milk are indirect products. Clothing is either directly (as flax and cotton) or indirectly (as wool, fur, and hides) derived from the soil, while our dwellings and fuel are often obtained from the same source. Exercise 1. Make a list of fifty things necessary to man and classify them as to whether they are directly, indirectly, or not at all derived from an agricultural soil. Since the soil is the source of all agricultural products. Fig. 1, some facts concerning its formation and nature should be understood before undertaking the study of the various farm products, whether they be of orchard, field, or dairy. Indeed the farmer cannot intelligently decide which of these products his farm is best fitted to produce until he has learned of which kind of soil his farm consists. FORMATION OF SOILS The materials from which all soils are formed are decayed rocks iand decayed plants and animals. The rocks furnish the various kinds of mineral found in differ- ent proportions in soils; and decayed plants and animals supply the organic matter also found in varying propor- tions in soils. 2 THE MANAGEMENT OF THE SOIL Many forces have been and are now at work breaking up and decomposing the rock material into minute par- ticles which form the basis of all soil. The action of these forces is both chemical and physical. Chemical action changes the composition of the minerals; that is, some element is added to or taken away from the mineral com- pounds. This process is one of combination or decomposi- PiG. 2. Erosion of Rock What agents are forming soil? Altitude — 5,000 ft.. So. Idaho. tion. It usually softens the material and opens it up to the action of other agencies of decay. Physical action, by which the rock is broken up into finer divisions, is called disintegration. When the rock material remains where it was before it was broken up, it forms residual soil. This varies according to the character of the rock from which it was formed and the mode and stage of disintegration. Water as a Factob in Soil Formation. Water has a powerful action on the process of rock decay. Rocks are porous and water passes through these pores. The great FORMATION OF SOILS 3 solvent power of water is increased by the absorption of oxygen and carbon dioxide from the air. The decomposed substances are often loosened, causing them to crumble and thus to be exposed to the action of other agencies of disintegration. (Fig. 2.) Rain. As rain sinks into the soil, it absorbs organic acids as well as many minerals which increase its solvent power below the surface. The amount of these dissolved materials is astonishing. It is estimated that the amount annually carried by the Mississippi River would cover a square mile of land to the depth of ninety feet. The great caves in many states, such as the Louray in Virginia and the Mammoth Cave in Kentucky, are striking examples of the solvent power of water containing carbon dioxide. Water exerts an important force in the disintegration and distribution of materials. During heavy rains, it forms into gullies and streams carrying all sizes of wash- able material. These loose fragments, whether sand, pebbles, or rock, cut down into channels making them deeper, grinding and polishing each other as they are carried along. Transporting and Assorting Power. The transporting power of water varies as the sixth power of its velocity; thus if the velocity of a stream is doubled, it can carry sixty-four times as much as before, but if the velocity becomes diminished one-half, it can carry but one sixty- fourth as much as before. This transporting power is of great importance to the agriculturist. A covering of loose material may be de- posited upon a basis of solid rock, great quantities of organic matter may be carried to enrich an unproductive soil, or fertile slopes uncovered by grass or trees may be entirely washed away. (Fig. 3.) Each gully along the field and roadside furnishes an excellent example of the transporting power of water. Exercise 2. Fill a bottle with muddy water from a roadside gully. Allow it to stand until the water is clear. Weigh the bottle and contents; pour off the water carefully, and weigh again. What proportion is sediment? 4 THE MANAGEMENT OF THE SOIL The variation in velocity and therefore in the carrying power of a stream causes an assorting of the material of different sizes; thus great beds of clay, silt, and sand have been deposited by streams in all parts of the country. Pig. 3. Tbees Pbotecting the Slope What effect has the rain had upon the soil where the trees have been cut away? Where the trees are still standing? How could this condition have been prevented? How would you remedy it now? Lake and Stream. Soils deposited by lake or stream are called alluvial soils. Flood plains deposited by overflow- ing streams are wider when the river bed is not steep, so that the velocity of the stream and its carrying power is lessened. The bottom lands of the Mississippi River and its tributaries are vast tracts of alluvial soils. Glaciers. In former, yet comparatively recent geologic times, glaciers, or moving ice sheets hundreds of feet thick, pushed down from the North over nearly all of the United States north of the Ohio and east of the Missouri rivers. These glaciers carried with them, or pushed along in front of them, great quantities of rocks of all sizes. By grinding against each other, these formed much fine material which, when the ice melted, was deposited in ridges or moraines, together with the sand and stones. Much of the finer material was laid down by the glacial streams. The material transported and deposited by the glaciers, being composed of all kinds of rocks, has formed some of our best agricultural soils. FORMATION OF SOILS Tempehatuhe. Heat increases the solvent power of water and hastens chemical action. Substances change volume with change of temperature. Alternate expansion by heat and contraction by cold causes the surface of rocks to crumble. Rocks are porous, though the per- centage of porosity to volume varies greatly in different kinds. These minute pores are usually filled with water. When water freezes, it expands about 1/11 of its volume. This exerts a pressiu-e of a ton to the square inch, shatter- ing the rocks and exposing their broken surfaces. Problem. What is the surface-area of a cubic foot of rock? What is its surface-area after it has been broken up into cubic inches? Chemical Action. In warm, moist countries, chemical action takes place more rapidly; while mechanical action goes on more rapidly under the effect of great alternations of heat and cold in temperate regions. When moisture is present, chemical ac- tion takes place be- tween the gases of the air and the minerals of the exposed rock. Oxygen unites with many minerals chang- ing their character. Iron united with oxy- gen forms rust which softens the rocks, causing their disinte- gration and decom- position. Carbon- dioxide acts upon limestone, causing it to crumble. Wind. The wind is both a disintegrating ^^ 4 ^^^^ Disintegrating Rocks and a distributing ^hat double purpose are these trees agent. Where there is serving in relation to the soil? c THE MANAGEMENT OF THE SOIL loose soil, particularly sand, the wind transports it, driv- ing it against and wearing away the solid rock. The soils of many large areas have been carried by the wind. Much of the loess soil has been thus deposited. Organic Agencies. Plants. Just as soon as the process of weathering will permit, some form of plant growth creeps in. Lichens throw out their slender thread- like organs of attachment which take up the substance from the rock for the nutrition of the plant. Great root- systems open solid rock and expose it to other disinte- grating forces. Trees and grasses open up and pulverize the soil by their root-systems (Fig. 4), but these are also a great protective agency in keeping the soil from being blown away by the wind or washed away by rains (Fig. 5). The acid of roots acts chemically upon soil-compounds, rendering them soluble. Roots absorb this soluble material for plant food. Bacteria are microscopic organisms in the soil. They are of vast agricultural importance. (See p. 23.) Fig. 5. Vegetation Photbcting Wisconsin Hilds What would happen to these hillsides, if they were fall-plowed and left exposed to heavy rains? FORMATION OF SOILS 7 Animals. Many burrowing animals, such as earth- worms, crayfish, moles, gophers, and prairie dogs, aid in ventilating, pulverizing, and enriching the soil. Organic Formations. These are made by accumula- tions of decayed plants mixed with the rock material which has been washed in. In shallow ponds or marshes where the water excludes the air and cools the tempera- ture, decay takes place more slowly than the deposits are formed, hence they gradually fill up with organic matter called muck or peat. Muck has reached a greater stage of decomposition than peat. When plants are ex- posed to the air on the surface of the soil for a sufiicient length of time, decomposition takes place to such an extent that little organic material is added to the soil. Humus. Is organic matter in a particular stage of decom- position. Its organic structure has been broken down and it has been reduced to a black, powder-like substance. Humus is formed chiefly by plants, often by the root systems of grasses and other vegetation with strong sys- tems of fibrous roots. Soils which owe their black color to the presence of humus are among our most fertile soils. Leaf Mold. This is more incompletely decomposed than humus. Field Trip — for observing the processes and agencies of soil forma- tion. Note the washing away of loose material by roadside gullies and by a stream. Is the stream muddy? If so, why? If not, why not? Take home a bottle of clear water. Evaporate a few drops of it to dryness on a piece of glass or on an evaporating dish. Is there any residue? Explain. Do you find any indications of underground streams? Of the assorting power of water? Do you see any results of the work of freezing? Of glacier? Visit an old railroad cut or a quarry and make a diagram showing stages of the disintegration of rock. Do you find any evidence of the effect of plants in the disintegration of rock? Note the depth of the root system of some tree whose roots are exposed along the bank of a stream. Dig up a clump of grass or a large weed and observe the extent of the root-system and how the soil particles are held by the rootlets. Contrast the bare slopes with grass-covered or wooded .slopes. In which is the soil protected from being washed away? Do you find leaf-mold or other vegetable formations? How does this soil compare with that of the field or garden? Write up your observations, answering all the above questions. 8 THE MANAGEMENT OF THE SOIL PROBLEMS 1. Look about in the vicinity of your school for rocks in various stages of disintegration and decomposition in the process of soil-formation, and write a description of them. Is their condition due to chemical or physical action, or to both? Explain. What growth did you find them supporting? 2. Find evidences of decaying organic matter in soils. 3. In accordance with what do residual soils vary? 4. Make a sketch of a stream, or gulch, in the vicinity showing the results of the disintegrating, distributing and the assorting power of water. What causes the assorting of material of different sizes? 5. How do you account for the variation in width of different flood-plains deposited by rivers? 6. Locate some alluvial soil in yom* neighborhood. How do you account for its deposition? 7. Explain the crumbling of the surface of rocks. 8. How do root-systems protect the soil? Make a sketch of the root-system of a plant and estimate its extent. AGRICULTURAL TYPES OF SOILS The rock particles of soils vary ia size from the coarse sand or gravel to those too small to be distinguished by the eye or the touch. The texture of soils has reference to the size of the separate particles, while the structure re- fers to the arrangement of these particles into crumbs or granules. The finest particles of soil material are called clay, the medium sized ones silt, and the coarsest ones sand. These and organic matter in the form of humus constitute the basis of all soils. The finer the particles of soil, the greater is the area of the exposed surface. Soils vary in surface-area per cubic foot from one-twelfth of an acre to nearly five acres. (See problem, p. 5.) Since much of the water held by soils consists of the film of water surrounding each soil-particle, clay or any fine soil has a much larger capacity than sand or other coarse soil. Chemical action and solution of plant food also take place on the surface of the particles, so the greater the surface-area (that is, the finer the soil particles) the greater is the supply of plant-food. Soils are named with refer- ence to the relative proportion of sand, clay, silt, and humus they contain, for no soil consists wholly of any one of them. Sandy Soil. A sandy soil contains a large proportion of sand. Its pores are larger but less numerous than those of clay and the circulation of air is freer. It is easy to work and can be worked early in the spring. It is, however, likely to dry out in the summer owing to its coarse open textm-e and its lack of vegetable matter. Clay Soils. These do not so readily dry out. The surface-area of soil particles is much greater, the water capacity more, and the solution of plant food more rapid ; but these soils are not so easily worked. Clay has a cohesive quality which makes it tend to form lumps. If 10 THE MANAGEMENT OF THE SOIL it is worked when wet it becomes puddled; that is, the granular structure is broken down and the soil particles are brought so close together that the air is driven out and its space filled with water. This property of soil which makes it possible for it to be molded or worked is called plasticity. Puddled soil bakes on top and while drying out shrinks, forming great cracks. Dry clay expands when moistened. This is shown by the cracking of a glass soil-tube which has been filled with dry clay and allowed to stand in water until the clay becomes wet. The expansion exerts sufficient force to break the tube. The finer the texture of a soil the greater is the shrinkage when dry and the expansion when wet. (See Fig. 7.) Loam. One can easily see that neither a coarse sand noi, a fine clay is most conducive to plant growth, but rather a mixture of both sand and clay, in which neither one greatly predominates with humus. Such a soil is called a loam. The Structure. The structure of the soil is the arrange- ment of soil particles into crumbs or lumps. It depends on the force of adhesion which holds the particles together. When two particles come into close contact, the film of water about each unites with that of the other, forming a single film inclosing both particles. In this way several particles may be held together in a crumb. A large number of these crumbs united forms a lump or clod. If soil con- tains too many hard clods they allow the air to pass through the soil too easily and it dries out quickly, while if it is composed of small crumbs which break up readily the soil will not so quickly dry out. Soils having a struc- ture favorable to plant growth are said to have good tilth. PROBLEMS 1. Explain the variation of the supply of plant-food with the variation in the size of soil particles. 2. (a) Which soil dries out most slowly? Explain. (b) What is meant by a loam.'* (c) How would you im- prove a sandy soil? (d) What soil is most conducive to plant growth? Explain. AGRICULTURAL TYPES OF SOILS 11 3. Define a crumb of soil. Distinguish between crumbs and clods. Which are more favorable to plant- growth, and why? 4. How would you prepare a good potting soil from a clay soil.'' How would you improve a clay soil in garden or field.? 5. What are the fundamental constituents of soils? 6. Name the agricultural types of soils. IMPORTANCE OF WATER Not only do plants consist largely of water, but all the food derived from the soil must be held in solution by water, since it can be transported to the different parts of the plant only when dissolved. Hence the problem of controlling the water-supply in the soil is an important one. Directions for preparing tin cans to be used in place of flower-pots. (Fig. 6.) 1) Mark the can with a pencil at the height (three and one-fourth to foiu' inches) which it is to be when finished. Sets of cans should be of uniform size. Fig. 6. Tin Cans Prepared for Flower-Pots 2) Make two cuts through the rim of the can about an inch deep and an inch apart. (Cut the seams and rim with the jaws, not the points, of the shears.) See Fig. 6. 3) Bend the cut piece back. Now insert the shears in this opening and trim off the rim smoothly and evenly. 4) Now clip the can all around the top about three-fourths of an inch apart and down to the mark. Bend each piecfe back tight against the can, making a smooth, even hem around the top. 5) With a heavy spike make about ten large holes in the bottom of the can, punching from within out. 12 IMPORTANCE OF WATER 13 Experiment 1. Water given off by a plant. (1) Prepare a gal- lon tin pail as directed and (2) transplant into it a tomato plant or any vigorous, single-stemmed weed. When its growth is established, (3) thoroughly moisten the soil and dip the lower end of the pail into melted paraffine to prevent any possibility of the escape of moisture from the bottom. (4) Fit a piece of heavy paper into the top of the pail close about the stem of the plant, wrap the stem secmely with cotton or soft cloth and pour melted paraffine over the paper to prevent the escape of moisture from the top of the soil. (5) Carefully weigh the pail and set it where it will be exposed to the wind and direct sunlight in the morning. In the evening weigh it again. Do this for several days and compare weights. How much moisture has the plant given off? It will be readily understood that in a warm, arid, or windy climate, more water will be given off than in a cold, humid region and more in a soil having high than in one having low water content. Exercise 3. Water constitutes plant-food. Take any large weed and carefully remove the soil from the roots. (1) Weigh the plant. (2) Hang it in a warm place until thoroughly dried out. (3) Weigh again. (i) What per cent of this plant was water? It is estimated that "to mature an acre of corn the crop must be supplied with 900 tons of water or an amount that would make a layer over the acre about eight inches deep." The amount lost from percolation or drainage practically equals that used by vegetation, so the precipi- tation required to grow one acre is about 1800 tons of water. Water constitutes about 80 per cent of a mature crop. The hydrogen and oxygen contained in the compounds constituting the dry matter of the plants amount to 10 per cent more and are obtained from water, making 90 per cent of the weight of a mature plant due to water. Water in the Soil. Man is not able to control the supply of water which falls in rain and snow upon the soil. But he can conserve the water after it is in the soil. The amount of water in a soil for the use of plants does not depend alone upon the supply of rain. Much depends upon the water-holding capacity of the soil, and the rapidity with which water is lost by percolation or evaporation. Gravitational Water. When rain falls it sinks into the earth by the force of gravity. The soil takes up all it 14 THE MANAGEMENT OF THE SOIL can; that is, it becomes saturated as the water passes through. That which drains off after the soil is saturated is called gravitational water. Since too much water drives out the air necessary for the growth of roots and for nitrification, it is injurious to most farm crops and it becomes necessary for the gravitational water to be removed by natural or artificial drainage. Capillary Water. After the gravitational water is drained off from the upper layers of the soil, the water remaining is in the form of films surrounding the particles and granules of soil and that which occupies the spaces between them. It is this film or capillary water which is available for the ordinary farm crops. Water is retained in the soil by two forces. One of these is adhesion; that is, the attraction between solids and liquids. This may be seen by dipping the finger in water and observing the film of water covering its sur- face when it is withdrawn. The other force holds the molecules of water together. The attraction of the water for the solid particles causes the film on their surfaces, but the attraction of the molecules of water for each other causes the film around each particle and crumb to become so thick that its own weight makes it drop off. Since the capillary water is held in films around the particles, the capacity of a soil for holding water depends very largely upon its texture. If the soil is uniform, the amount of capillary water diminishes as the distance above saturated soil increases. Experiment 2. Secure three capillary tubes, one with a coarse, one with a medium and one with a fine bore. Stand them in a glass containing a little water colored red with ink or other coloring matter and notice the difference in height to which the liquid rises in the tubes. The attraction of the wall of the tube for the water draws it up. The pores of a gravelly or sandy soil com- pare with the larger tubes, while the pores of clay, or fine soil, act as the fine tube. Experiment 3. Effect of Texture on the Rise of Water. (1) With cotton, tightly plug the bottom of each of three glass tubes eighteen inches long and about three-fourths of an inch in diameter. (2) Fill each tube with one of the following air-dried soils, tamping it down IMPORTANCE OF WATER 15 evenly as the tube is filled : one with coarse sand, one with garden loam and the third with garden loam with a six-inch layer of gravel six inches from the top, then fill up the tube with loam. (3) Stand the tubes in a pan of water as in Fig. 7, and allow them to remain for several days. (4) At intervals from day to day, record the height of water in each un- til it no longer rises in any of the tubes. (5) In which tube 'does the water rise highest? Why? Why is there a differ- ence in the height of the water in the second and third tubes? Structure, or the size of the soil granules or crumbs, also influences the water-holding capacity. Loosening increases the water-holding capacity of clay soil and diminishes that of a sandy soil. Humus has great water- holding capacity. Hence, be- cause of the humus in them, a clay loam has a greater ca- pacity than clay and a sandy loam greater than that of sand. Experiment 4. Effect of Texture on Water-holding Capacity, Rate of Percolation and the Absorption of Plant Food. In this experiment use the apparatus for Experiment 3. (1) Fill three tubes half -full of air-dried sand, clay, and loam respectively; wrap each tube with a soft string or cloth strip so it will not slip down in the rack and suspend it over a small glass. (2) Fill up each tube with water leached from stable compost. (3) Record the time at which the water is applied, the time when it begins to drip from each soil, and the time it stops dripping. (4) Judging from the color of the drippings, which soil will absorb the most plant food from the water passing through it? What effect does the texture of the soil have upon the amount of water percolating through it? What effect upon the rapidity of perco- lation? (5) After the water has quit dripping, weigh each tube and compare the weight with its former weight. Which soil retained the greatest amount of water? Explain. Temperature of the Soil. There are many factors influencing the temperature of the soil. Some of the impor- tant ones are moisture, composition, color and situation. Fig. 7. Apparatus for Experiment 3 16 THE MANAGEMENT OF THE SOIL Exercise 4. (1) On a bright morning select a dry spot in the garden or yard with free exposure to the sun and wind. About ten feet from this spot, where the soil and conditions are similar, select a second spot of soil and saturate it with water. (2) In about twenty-four hours, place a soil thermometer with its bulb covered about two inches deep in the soil of each spot. In an hour or two read each thermometer. Which is warmer, the wet or the dry soil? Explain. If weather conditions are unfavorable, perform the above experiment in tin buckets of soil in the laboratory. A quantity of dry soils (sand, gravel, clay, and loam) should be collected in the fall and kept on hand for indoor experiments. Fig. 8 Soil Bin. Fig. 8. A Foub-Compartmbnt Soil Bin Used at State Normal School, Albion, Idaho. Exercise 4 shows that a wet soil is cold. Since clay has a firm texture and, hence, a greater water content than sand, sand is warmer than clay. In the evaporation of water much heat is used, hence the more water which evaporates from the surface of a soil, the lower the tem- IMPORTANCE OF WATER 17 perature will be kept. A soil mulch stops the evaporation and thus increases the temperature of the soil. Exercise 5. Influence of Slope on Temperature. (1) At the same time, take the temperature on both the north and the south sides of a slope and compare the readings. (2) What causes this difference in temperature? See diagram. If you can find no natural slope, throw up a short ridge of soil and test each slope of it with the soil thermometer. When the sun shines upon the surface at a right angle (see Fig. 9) as upon a southern slope, it is not spread over Fig. 9. The Sun's Rays on a Northern and a Southern Slope Note the difference in the angle formed by those of a-b and that formed by those of c-d. Which group of rays spreads over the greater area upon striking the earth? so great an area as when it falls at an inclination as it does on a northern slope. The less surface over which the rays are spread, the more heat they supply to a given area; hence the difference in temperature between a northern and a southern slope. Thus the southern slope has an advantage for an early garden and a northern slope for retarding fruits from blossoming before the danger from frost is past. The color of a soil also some- what affects the temperature. Black absorbs the heat; hence a dark soil is warmer, other conditions being equal, than a light-colored one. 18 THE MANAGEMENT OF THE SOIL PROBLEMS 1. Explain why the control of the water-supply in the soil is such an important problem. 2. Distinguish between capillary water and gravita- tional water. Which is used by plants. J" 3. Why is a saturated soil injurious to most farm crops? How would you improve it.' 4. Upon what does the water-holding capacity of a soil largely depend? 5. How would you improve the temperature of a cold soil? 6. a) Explain the difference in temperature between a northern and a southern slope. Illustrate by diagram, b) How would you utilize a southern slope on a farm? A northern slope? SOIL MANAGEMENT Drainage. The value of drainage is not fully realized or more land would be drained. True, it is considerable trouble and expense. So it is well to consider first whether the land is worth draining. Is the soil fertile? Is there no reason why good crops should not be raised if the land were drained? Is it located so that the crops could be disposed of to advantage? Granting fertility and other favorable conditions, it is believed that the increase in yield the first two or three years will entirely cover the cost of drainage (Fig. 10). ■^« 1 F ^^ Fig. 10. Tile Drainage Increases Barley Yield At Superior tile drains nearly tripled the yield. This will depend somewhat upon the character of the crops. Truck crops, potatoes, and orchard fruits, or intensive farming, would pay more quickly for the expense of draim'ng than would hay and grain or extensive farm- ing. Drainage makes permanent results, therefore it is a good investment. 19 20 THE MANAGEMENT OF THE SOIL Need of Drainage. There are several kinds of soil which need drainage: that which is wet because of a low, flat situation (see Figs. 11 and 12); that which has such a large percentage of heavy clay that the water cannot percolate through it; that which has a subsoil of im- penetrable clay and hard pan; and that which has an ex- cess of alkali. Fig. 11. Undrained Land, State Test Fabm, Willahd, N. C. (Cowpeas after two plantings of corn the preceding spring.) Why is there no crop? The indication that a soil needs draining may be the character of the vegetation upon it. If the soil is covered with sedges and water-loving plants, if the ordinary farm- crops turn yellow when they should be green; or if the plants be such as grease-wood and salt weeds which indicate the presence of an alkali, drainage is needed. MANAGEMENT 21 Surface discolorations of the soil may also reveal the excess of alkali and the consequent need of drainage. (See p. 24.) Effects of Drainage. (1) Drainage increases the avail- able water supply of plants. The gravitational water is removed from the upper layers of the soil by drainage, but, strangely enough, the water available for farm crops is not removed. In fact this available supply is increased ; for the water held in the pores and upon the surface of the soil-particles is not carried off by drainage, but is held in the soil by capillary attraction. This capillary water is Fig. 12. Cowpeas and Corn on Same Land as Fig. 11 After Tile Drainage — Corn in Place of Timber available only in the unsaturated soil above the water- level. Drainage lowers the water-level, thus increasing the space for capillary water and the supply available to plants. This lowering of the water-level increases the depth of the root-zone. Roots cannot grow in water- soaked soil. If the water-level is near the surface, the root growth is short; if the water-level is deep, the roots grow deep (Fig. 13). This not only increases their water supply, but makes that supply available in time of drought when shallow-rooted plants would suffer. This greater depth of the root-system brings the rootlets into contact with a far greater number of soil-particles from which to obtain plant-food, thus greatly increasing the avail- able supply of food for plants. Again drainage increases the available water-supply by improving the structure, or soil granulation. When a 22 THE MANAGEMENT OF THE SOIL soil remains wet, it tends to puddle or combine granules, while the alternate moistening and drying out promote granulation. This granular structure increases the pore spaces and tends to retain the capillary water, making the supply less variable. (2) Drainage improves soil ventilation. In a water- soaked soil (see Fig. 11), the pores are all so completely filled with water that the air is driven out. When the Fig. 13. Effect of Tile Drainage on Growing Crops Why does one of these plants have a deeper root system than the other? Which plant will stand the drought of late summer better? Explain. free water is removed by drainage, air is permitted to enter. The improved granulation also increases the pore space and this insures a free movement of air. The tile drain is filled with air when not full of water. This soil air promotes chemical action, rendering plant food soluble and hence available. (3) Drainage increases the temperature. The tempera- ture of a soil is greatly affected by its water-content. A wet soil is a cold soil. It takes far more heat to warm the water than it does to warm the soil particles to the same degree of temperature. Evaporation of water is a cooling process. It takes as much heat to evaporate one pound of water as it does to bring three pounds of ice to the boiling point. Drainage carries off the surface water early in the spring, and the sun's heat has a chance to MANAGEMENT 23 warm the soil. It allows the soil to be warmed by warm rain water percolating through it, whereas it would run off of a saturated or undrained soil. On a windy day, when the water evaporates rapidly, the difference in tempera- ture between a drained and an undrained soil is often as much as ten or twelve degrees. This increase in temperature in a warm soil permits early planting (planting may be done from one to two weeks earlier on a drained soil) and lessens the danger of frost in both spring and fall, thus lengthening the grow- ing season. The early planting gives a chance for strong root development before the top growth is established. (4) Drainage favors desirable soil organisms. The organic matter in the soil, such as animal refuse and decaying plants, must be broken down into simpler com- pounds. This is brought about chiefly by bacteria and other small organisms. Through their action on organic matter, they render the organic forms of plant food avail- able. Nitrates are constantly being formed in the soil by certain bacteria. It has been shown that drainage favors both plenty of air and a warm temperature, hence it is conducive to the activity of nitrate-forming organisms, and thus increases plant-food. (5) Drainage prevents erosion and conserves soil fer- tility. A drained soil, on account of its granxilar condi- tion, is more porous and absorbs the moisture which would otherwise run off of the surface, carrying much of the fertile soil and cutting the loose surface into gullies. (6) It reduces the process of heaving. When a soil is water-soaked, there is but one direction in which it can expand when frozen; that is upward. This lifts the plants with the soil. When the temperature becomes warmer and the frost is out of the ground, it settles back, leaving the plants heaved above the ground, a condition which often kills them. Where deep drains lower the water level, the soil spaces give room for expansion, and so much heaving will not occur. (7) Drainage removes excess of alkali (Fig. 14). Very little undrained, irrigated land is free from seepage and accumulations of alkali. Irrigation raises the ground water 24 THE MANAGEMENT OF THE SOIL level, which brings with it in solution the salts taken out of the soil. When the water is brought to the surface by capillary action, it evaporates, leaving the salts near the top of the soil. These in time accumulate until vegetation 1915 April MAY JULV OCTOBER] 2 25% Before drainage. l.oo'/' E ffect aFremoyal of "^"^^^^excess water in soil. ^Effect cf irrigation f vnr'Ini^ltmi in nimmA \ii^l^^^„^^^^EffectoF irrigation i^— Effect of copious flooding. Fig. 14. Diagram Showing Typical Reclamation of Alkali Lands Quantities are percentages of total salts in first 4 feet of soil. cannot grow. If there is underdrainage (Fig. 15) and the surface is irrigated, the water carries these salts down into the soil where they are carried away with the water of the drain and so accumulations of alkali do not occur. Fig. 15. Drain Properly Laid to Carry Off Seepage Experiment 5. Effect of Drainage on Alkali Soils. Punch holes in the bottoms of two gallon cans. Fill each with field soil charged with alkali. Allow one can of soil to stand in water which shows no trace of alkali when tested with the litmus paper, and allow evaporation from the surface of the soil to take place freely. Water the soil in the other can freely from time to time with the same kind of water, allowing it to MANAGEMENT 25 drain off through the holes in the bottom of the can. After a week or ten days, observe the difference in coloration of the surface soil in the two cans and test these soils for alkali as in Exercise 6. (8) Drainage gives permanent results. If the foregoing improvements of the soil are made by drainage, there can be no doubt of the increase of the annual yield of crops upon drained land (Fig. 16) so that the value of both land and crops is permanently increased. Fig. 16. Land Reclaimed by Drainage But there is another important benefit to be derived not only by the owner of the land, but by the immediate community as well, and that is the improvement in sanita- tion which comes through the effects of drainage. There is nothing so conducive to malaria as an undrained swamp which forms a breeding place for mosquitos by the million. The early settlers of our prairies can offer evidence of the great improvement in conditions of health which prevail since the land has been drained over those which existed when the land was first settled and, of course, undrained. Experiment 6. Effects of Drainage. (1) Punch holes in the bottom of a gallon can and place in it an inch or two of coarse gravel. (2) Fill the can with soil composed of one-fourth sand and three-fourths garden loam. (3) Fill a second gallon can, in which no holes have been punched and no gravel has been placed, with soil similar to that in the first can. (4) Plant grains of corn in each can, carefully moistening the soil, using the same amount of water for each can. Keep the cans where they will THE MANAGEMENT OF THE SOIL get plenty of air and sun and at regular intervals sprinkle each with the same amount of water. (5) Place a soil- thermometer in each can, with the bulb at a depth of two or three inches. From time to time, note the temperature in each can. (6) If each of these conditions of soil moisture existed in open fields, in which field would the temperature be higher? Why? Which field would suffer most in heavy rains? Why? (7) In a few weeks empty the cans and find out in which one the roots have penetrated deeper. Under which of these soil conditions in the open field would plants best withstand a subsequent drought? Why? See Fig. 13. Types of Drainage. There are two general types of drains, the surface drain and the under-drain. The surface drain costs less to begin with, but is less efficient than the tile drain and is expensive to keep open. It is wasteful of land by occupying space which should be given to crops. The banks are likely Fig. 17. Laying a Tile Drain Where does the water enter this drain? What relation does the area drained have to the depth of the drain.'. to cave in or to be washed into gullies. There are, how- ever, a few conditions where surface drains are advan- tageous. When the amount of water to be carried off at certain times is too great for the ordinary tile drain, when the water-level is too near the surface or the slope is too slight for the satisfactory working of the tile drain, surface draining should be used. The under or tile drain (Fig. 17), while more expensive to put in, is a permanent investment and, if properly laid, seldom requires much attention afterwards. A drainage system consists of lateral pipes, submains and mains from MANAGEMENT 27 HI Gr ^7' Ound 1 \ * •^ V \ \ '^i4 / / // Natural Sysiem { Intercepiing Sysiem Gridiron System Herring Bone Sj'slem Fig. 18. Arrangements of Drains 28 THE MANAGEMENT OF THE SOIL Fig. 19. A 4x6 Inch Y-TlLE many parts of the field to the outlet, thus making a continuous channel for the flow of water. The careful planning of this system (See Fig. 18) has much to do with its efl&ciency as well as its cost. The proper distance between the laterals will depend somewhat upon the character of the soil? In loose sandy or loam soils, drains one hundred to two hundred feet apart will furnish sufficient drainage, while in heavy clay soil they wiU need to be placed only thirty or forty feet apart. The size of the tile to be used will depend upon the amount of water to be carried off. Four- inch tiles (Fig. 19) are generally advised, as smaller ones are likely not only to be insufficient but to get clogged up. Since the water enters the drain only at the joints, it is best to use short tile. (See Fig. 17.) Burned clay or concrete is used for permanent drains. The depth of the drain depends upon the situation of the land and upon the subsoil and there- fore of the water-level. If the drain is too shallow, the tiles are likely to be injured by frost. The deeper the drain, the wider is the area drained. Four feet is con- sidered deep drainage, three feet medium, and two and one-half feet, shallow drainage. Tillage. Tillage includes all manipulations of the soil required for the preparation for the planting of the seed and for the cultivation of the crop. It accomplishes several important results. Effects of Tillage. (1) Tillage prepares the seed-bed for the germination of the seed. Air, moisture and warmth are favored and the growing plant insured a mellow yet compact soil for the development of a strong root-system. (2) It increases and conserves the soil moisture. It increases the soil moisture by increasing the absorbing power of the soil. A plowed soil will absorb much more MANAGEMENT 29 water than a compact soil with a smooth hard surface. This is one advantage gained by fall plowing. A mulch of finely pulverized dry soil on the surface conserves the moisture by breaking the capillary flow of water, and thus prevents its evaporation. This is the reason a harrow should immediately follow spring plowing (Fig. 20), and that a cultivated crop should have shallow cultivation as soon as possible after rain or irrigation. King found by experimenting with a cultivated and an uncultivated Fig. 20. Conserving Moisture "Promptly mulching plowed soil with a toothed harrow improves the tilth and conserves the moisture." field lying side by side that cultivation, by preventing evaporation, saved 1.7 inches of rain-fall in forty-nine days. (3) Tillage destroys weeds. Thereby it saves the mois- ture and plant-food, which they would use, for the grow- ing crop. (4) It incorporates crop-residues and animal waste in the soil. Thus it promotes the formation of humus. So, in many ways, tillage may be used to render plant-food available to the growing crop. Kinds of Tillage. The kind of tillage needed depends upon the character, condition, and location of the soil and upon the purpose for which tillage is performed. 30 THE MANAGEMENT OF THE SOIL (1) Plowing. Plowing breaks the soil into thin layers, rearranging the soil particles. It should never be done when the soil is wet enough to puddle, as this tends to force the particles together in large masses which, when dry, form clods. If plowed when too dry, it either breaks up into clods or forms separate grains which, when wet, become united into masses that also form clods when dry. This exact condition with regard to moisture at the time of plowing (see p. 10) is of utmost importance. Special care should be taken not to plow a clay soil when wet; it will injure its tilth for several years. If a heavy clay soil, which is not too wet, is plowed in the fall, and left with the rough surface exposed, its tilth will be improved. Of course, this should not be done where the slope is too great or the rains too abun- dant, for plant-food would be lost by leaching. If a loose soil is left exposed on sloping ground during a wet season, much of the soil itself will be carried away by the water. Fall plowing is advisable for sod or stubble, since it gives a chance for the vegetation to be broken down and for the furrow-slice to become reunited with the subsoil. Land that is known to be infested by insects is benefited by late fall plowing, as this exposes the pupae and eggs to the frosts of winter and to the reach of birds. Fall plow- ing should be done as soon as possible after harvest to prevent the evaporation of moisture from the surface. This promotes the sprouting of weeds to be killed by the frost, whereas if the ground remained unplowed, the weed would remain unsprouted ready to germinate in the spring. Most cereals do best on fall-plowed ground, unless fol- lowing a well-tilled crop. Fall plowing is also advisable where the amount of rain- fall during the year is limited, or where its distribution is restricted to winter and spring. The rough, plowed siu-- face absorbs the rain and the melting snow (Fig. 21); while a smooth, compact surface (Fig. 22) would allow the water to run off. Fall-plowed land should be harrowed or disked as early in spring, as conditions of soil and season will permit, to warm the soil by preventing so great evap- MANAGEMENT 31 a p ■♦-» B .a o -a Pi a (3 ■© 13 32 THE MANAGEMENT OF THE SOIL oration of moisture, as would otherwise take place on land compacted by settling and by the winter rains. Early spring plowing and harrowing are important. This conserves the moisture furnished by the winter rains and stirs the soil when it is in the best condition to im- prove its structure. It also gets the ground into condition to absorb the spring rains as well as preparing it for the seed bed of spring crops. (See Fig. 20.) Fig. 22. Showing Wasting and Compacting of Fall-plowed Land Due to Its Being Harrowed and Worked Down in Fall. Lewistown, Idaho. The depth of fall plowing, unless for an immediately sowed crop, should be greater than spring plowing, and heavy soils should be plowed deeper than light ones. This brings the compact subsoil to the surface and thoroughly covers vegetable refuse, when present. Light soils should be plowed at less depth to avoid making them too loose and it is better in their case to mix the organic matter with the surface soil, though it should be suffi- ciently covered. A wet soil should have more shallow plowing than a dry soil. If a grain stubble or a cover crop is to be turned under, it should be plowed deep enough to get it out of the way of the harrow and cultivator. MANAGEMENT 33 o Pi o p g O 34 THE MANAGEMENT OF THE SOIL New land should not be plowed too deep the first time, as it is better to increase the depth of plowing a little each year, to avoid the formation of a compact subsoil or hard-pan by the tramping of the horses at the same depth each year. Subsoil plowing is beneficial to heavy clay soils; the loosened subsoil is covered by the next furrow-slice so it is not left dried-up on the surface. Certain kinds of plows are required by certain kinds of soils. The condition of the soil and the kind of crop to Fig. 24. Mulching With a Disk follow must also be considered in selecting the type of plow and the shape of mold board. Clay land requires a different plow from a sandy loam, and fallow land from sod, and the hillside a different one from that required for the level plain. (2) Rolling. The corrugated roller is used to pack the soil just beneath the surface. It consists of a series of wheels on a single spindle. (Fig. 23.) These corrugations leave the surface rough and easily harrowed, or on a loose soil harrowing is not necessary, for the rough projections settle or blow together, forming a light mulch. A disk weighted and set to run straight may be substituted if the corrugated roller is not available. (Fig. 24.) MANAGEMENT 35 Sub-surface packing causes an increase of upward move- ment of capillary moisture and an increase of tempera- ture by conducting the heat from the surface downward. A compact soil is often two or three degrees warmer than it would otherwise be; this hastens germination. It is advantageous on sandy soil, in dry or semi-arid regions, or wherever a heavy crop of green manure or stable litter is plowed under. The roller should not be used on wet clay soil, as it tends to puddle. Fig. 25. Spike Tooth Habeow (3) Disking. Disking may be of advantage to cut up sod land before plowing and to cut up the furrows when sod or green manure has been turned under or in any case where the furrow-slice needs cutting up before har- rowing. (4) Harrowing. Except in fall-plowing, the harrow should usually soon follow the plow so as to avoid the evaporation of moisture and the formation of clods. The harrow pulverizes the soil (Fig. 25) and forms an excellent mulch for preventing evaporation. It may also be beneficial in ridding ground of weeds, provided it is used when they are extremely small so that the sun will destroy their tender, upturned roots. 36 THE MANAGEMENT OF THE SOIL (5) Cultivating. Cultivation of a growing crop de- stroys weeds which would rob the soil of much moisture (see p. 50) and plant-food. It aerates the soil, insures moisture and renders plant-food available. It necessarily varies with the condition of the soil, the age of the plants, and the kind of crop. Light, or so-called blind cultivation, may be given before the seed is up. Early cultivation when plants are small may be several inches deep, but it should not be too close to the plants and should leave a complete mulch. Cultivation should follow irrigation or rain (Fig. 26) as soon as the soil is in proper condition, in order to break the crust and to renew the soil mulch. If this is not done, often more water is lost through evaporation than was received. The mulch of a heavy clay soil is sometimes * :i t . las wt gs fUli m H 9 P ^£^ HB^SHH imi rd ^m & ^ i ^nE p|||j|iM^H IH «1 "^hB S M j^g^A ^^Jt^^^v^&^^v^SSe Fig. 26. Mulching with a Two-row Cultivator destroyed by the absorption of moisture from the atmos- phere, if it continues humid for several days, and it will be necessary to cultivate the soil to renew the mulch. A mulch should be loose and dry, but not too fine. Three inches deep is suflBcient and as the crop grows, cultivation should become more shallow, as deep cultiva- tion will injure the roots. MANAGEMENT 37 Experiment 7. EfEect of Humus and Soil Mulches on the Conserva- tion of Moisture. (1) Take four gallon pails or cans, with holes punched in the bottom and provided with wire bails. Cover the bottom of each can with coarse gravel. (2) Fill them as follows, firming the soil in well as each is being filled: entirely fill two cans with garden soil; fill the third can with the same soil to within two inches of the top; for the fourth can, mix the garden soil with one-fourth the amount of humus and fill to the top. (3) Stand the four cans in a shallow pan of water overnight or until the surface of the soil becomes moist. (4) Remove them from the water and allow them to stand until the soil is dry enough to cultivate. (5) Cover can number 3 with a mulch of straw; leave one can of garden soil uncultivated; and cultivate soil in the remaining two cans to a depth of two inches. (6) Weigh each can and record the weights. (7) Place all under similar conditions, exposed to sun and wind, but protected from rain, and keep the soil mulch from becoming compact. (8) In a week or two weigh all cans again and compare present weight of each with its former weight. (9) From which soil did the water escape most rapidly? From which most slowly.'' Why? How did the water escape? Carefully dig down into the soil in each can and compare the distances from the surface to moist soil. Which mulch, the straw or the soil one, is the more effective? Which of these soils represents a cultivated soil? Which a compacted soil? Which is like an unplowed field in late spring? How can evaporation of moisture from a field be stopped in early spring? How does the addition of humus affect the moisture of the soil? How are soils compacted? Effect of mulch on alkali formations? Irrigation. One of the greatest agricultural problems is that of obtaining a sufficient and properly distributed water supply. Addition of humus to a soil increases its water capacity; tillage conserves the natural water supply; irrigation increases the supply by directly applying water to the soil, and distributes it when and where desired. Thus its distribution may be controlled, an achievement impossible when the natural precipitation is depended upon. There are between fifty and sixty million acres of irrigable land in the United States and this is but a small fraction of its arid territory. A sufficient and controllable water supply would make this not only an agricultural but an inhabitable country. Growing trees would afford refreshing shade, giving relief from the intense heat, as well as beautifying the landscape. Conditions Necessary. In many places water is not available for irrigation. A hard impervious stratum between the first and the fifth foot in depth prevents the storage of moisture and the development of deep root- 38 THE MANAGEMENT OF THE SOIL systems, while a porous stratum of coarse gravel near the surface allows the water to percolate beyond the root zone, and thus some of it is wasted. Though wasteful of water, the porous stratum insures drainage and is to be preferred to the impervious stratum. An examination of samples of soil obtained at different depths by a soil auger (Fig. 27) will aid in determin- ing the character of the subsoil. The character and depth of the soil should be considered. Most of the soil in mountain valleys is extremely deep — sometimes a uniform depth of thirty to forty feet is found. Sandy loams take irrigation well, but clay absorbs water slowly. It cannot be culti- vated when wet, and bakes and cracks open when it dries. A uniform slope of ten to twenty feet to a mile and an even surface are desirable con- ditions. On irregular ground, the open irrigation ditch is impracticable. If the land has not a natural drainage, it should be supplied artificially as soon as possible. The presence of injurious alkali is indicated by such native plants as grease-wood and salt weeds. Exercise 6. Perform exercise 7 using field soil suspected of being charged with alkali. If the litmus paper when taken out of the soil mass and dried is turned blue, the soil is alkaline and should be subjected to chemical analysis. When there is no under drainage, alkali salts are often brought to the sm'face, severely injuring the soil. (See Exp. 5.) When an irrigating canal is run through a porous soil, a surprisingly large per cent of the water seeps out into the soil on either side of the canal, and is carried FiQ. 27. (a) — Soil Auger (b) — Earth Auger and a 4 FT. Length of }^ In. Gas Pipe FOB Extending Soil Auger MANAGEMENT 39 laterally to the lower levels where it comes out to the surface. In time, the soil at these low places is completely saturated with water, but that is not all that unfits it for the growing of cultivated crops. As the seepage water percolates through the soil from the canal to the lower levels, it absorbs much of the mineral salts in which these soils abound, and becomes alkaline. Later the water evaporates from these lower surfaces, leaving the alkali salts behind. This forms spots (Fig. 28) or even beds of Fig. 28. Alkali Spot in a Field Can you find such a "spot" in your locality? What would you do if this were your land? How could this condition have been prevented? alkali, rendering the land unfit for growing crops. If in a year or so after the irrigating canal is made, a drain parallel with it is laid (its distance from the canal being governed by the position of the outcropping of the water) the surplus or seepage water will be carried off by the drain and injury prevented. Economy in the use of water and fre- quent cultivation of the soil lessen the evaporation and hence decrease the deposits of alkali salts. The Time for Irrigation. The time to irrigate depends upon many conditions. A heavy soil with a compact subsoil should have few and heavy irrigations at long 40 THE MANAGEMENT OF THE SOIL intervals, as such a soil holds water for considerable time. For a more open soil frequent light irrigations are required. When a crop is planted, the soil should contain enough moisture to supply the plants until they are large enough to shade the ground; at this stage, the crop should have its first irrigation. The appearance of the plants is the surest guide as to when irrigation is needed. A yellow- green foliage indicates too much moisture and consequent ^Hiii r^'"™! " '-{•~- ... "^ ,<»%» /iM^is ^ '^':-:iM'' : '^iK' l''''-l^'k0$:- ,^ia^^' ■■■"■^■'- ■ '■■ '%-'..^J-4^/ ' ^^^ ■■■:"■■■ '■•' . 4W, ■ il*^ Fig. 29. Bog Produced by Over-irrigation lack of air, while a very dark green or wilted foliage indi- cates a low moisture content of the soil. Frequent light irrigations are usually less desirable than heavy, less fre- quent ones, as the latter induce deeper root-growth, and the water lowers the temperatiu-e of the soil and it re- quires time to recover its normal warmth. The Supply of Water. Water for irrigation purposes may be obtained from government projects or from private companies. Reservoirs are built for the storage of water during the winter to be used when needed for irrigating purposes. The water itself should be free from injurious materials. The supply should be available during the growing season and should be sufficient to cover the MANAGEMENT 41 required area quickly. If it moves quickly over the field, it will reach the farther end before the end near the main ditch gets too much water. Yet there should not be such a volume of water as to over-irrigate (Fig. 29) or to wash off the soil of the near end before reaching the farther end of the field. Preparation for Irrigation. After the ground has been plowed and pulverized, it should be carefully leveled (Fig. 30) so that the water will not stand in the hollows and leave the high places dry. Fig. 30. Fresno Grader — Grading New Land for Irrigation Permanent ditches should be carefully laid out. If the fall is slight, this should be done by a competent engineer. The engineer's level and rod are most satisfactory for laying out the ditches. Some, however, use a straight edge with level, a rod with legs attached, and a level in the center. The leg on one end is longer by one-fourth, one-half, or three-fourths inch (according to the grade desired) than the leg on the other end. The grade is established by working with the longer leg down the ditch and making the grade so as to keep the bubble in the center of the level. Banks of ditches should be graded, smoothed, and firmed so that weeds may be easily cut and burned. Alfalfa or some rapidly growing forage crop may be sown along the banks to keep down the weeds. Owing to the fact that it furnishes a place for breeding and scattering 42 THE MANAGEMENT OP THE SOIL weed seeds and insect pests, some farmers plow in the head ditch as soon as the irrigating season is over. Systems of Irrigation. The two systems in most com- mon use are the flooding system and the furrow system. The method to be used is determined by the slope of the land, the character of the soil, and the kind of crop to follow. The Flooding System. Flooding is often used for meadows, grain and alfalfa fields. Soil must be of such a character that it does not bake and the land should be slightly rolling, but not enough to cause washing of the soil. This system does not require so much preparation of the land as the furrow system. From the head ditch the water may be distributed over the field by small ditches called laterals from which it is turned out at intervals; it is forced over the surface by their overflow, which results from the damming of the ditch below a certain number of laterals until they are filled to over- flowing. A temporary dam is then placed in each of these laterals, causing it to overflow. The dam in the head ditch is then moved farther down and the water is thrown into another set of laterals. These are treated as the first set was, and this is continued until the whole field is flooded. Often the surface of the land is made level or nearly so. A head ditch is made having but a slight grade. From this head ditch, in the direction of the desired slope, low levees are constructed from sixty to one hundred feet apart, checking off the entire field. The grade of these checks' will vary with the character of the soil. If the grade is too great, the supply head will wash the soil from the upper portion of the checks and damage the crop by exposing the roots. In the case of long checks the practice is to throw up the levee by turning a plow furrow in one direction and then plowing back in the same furrow and turning the soil in the other direction. This is to correct unevenness so that by the time the levee is in good condition a ditch has been made that will serve to carry the water down and onto the lower portion of the check. This carrying the water down the sides of the levees is MANAGEMENT 43 made necessary in the case of long fields to avoid over- irrigating the soil at the head before the water can reach the lower end. This makes a ditch between the checks. The levee is usually finished on each side with a shovel. When the grain crops are ready to harvest, these ditches are usually plowed in to make it easier to cut the grain. The Furrow System. The furrow system of irrigation is used to better advantage where the soil is apt to bake and crack, where the slope is steep, or where an orchard or cultivated crop is grown. In this system, the water runs through the field in small furrows. It percolates laterally through the soil and does not run over the entire surface. The irrigator may use as few or as many furrows as are needed; the distance between them depends upon the nature of the crop and the character of the soil. The high places are first leveled off, filling up all hollows. (See Fig. 30.) Crops are planted in rows which may run with the slope or in gradually descending courses along the hillside. The main supply ditch furnishes water for smaller head ditches at intervals in its course. These supply water for Fig. 31. Effect of Irrigation Without Cultivation Corn cut away to show a baked and cracked soil. The corn should have been cultivated after the irrigation, as soon as the soil was sufficiently dry. 44 THE MANAGEMENT OF THE SOIL the irrigating furrows between the rows. When the fur- rows leading from the upper head ditch have been sup- plied, the water is turned into the next head ditch and another set of furrows is irrigated. If the furrows are long, cross ditches or drains may be used to run across the field to take up the water from the furrows above them and in time supply the furrows below them. While it is more expensive to install, the fiu^row system is less wasteful of water, and gives better results, since the water does not flow over the surface causing the soil to bake and crack. It permits cultivation (which is just as essential after irrigation [Fig. 31] as after rain) to keep Fig. 32. Prepaking the Seed Bed fob Alfalfa Using a spring toothed harrow and a plank drag in the preparation of the seed bed for alfalfa. S. N. School, Albion, Idaho. What is the purpose of the plank drag.!" the soil mulched, preventing evaporation and the con- sequent great loss of moisture, and to allow free circula- tion of soil air. In order to keep the water from running over the surface, the furrows should be narrow and deep rather than wide and shallow. ExPEBiMENT 8. Furrow Irrigation, Showing Lateral Capillary Move- ment by Water. (1) Fill a soap-box with air-dried soil, tamped in or allowed to settle sufficiently to make it like well tilled soil. (2) In the center make a narrow furrow three inches deep running across the short way of the box. (3) Fill the furrow with water to within an inch of the top. Refill the trench several times; that is, keep water in it for a half- MANAGEMENT 45 hour or more. (4) The next day remove two inches of the surface of soil and measure the distance the water has traveled laterally; remove another two inches of soil and measiu-e the lateral extension of water again. Repeat this again. (5) Compare the lateral extension of water at different depths of soil. AVERAGE OF SIX YEARS' RESULTS^ WITH DIFFERENT QUANTITIES OF IRRIGATION WATER AND MANURE Irriga- tion Grain, Bushels per Acre Stover, Tons per Acre Water Applied No 5 Tons 15 Tons Aver- No 6 Tons 15 Tons Inches Manure Manure Manure age Manure Manure Manure Average None 51.9 73.3 75.9 67.0 2.111 3,254 3,921 3,095 5 61.0 86.1 91.4 79.5 2.325 3.776 4.485 3,529 10 59.7 83,0 92.5 78.4 2.556 3.728 4,252 3,513 20 67.6 87.7 99.1 84.8 2,814 4,037 4,855 3,902 30 63.1 90.4 95.7 83.1 2.859 4,198 4.773 3.948 40 63.9 83.8 90.0 79.2 2.878 4.073 4,501 3.817 Aver- age 61.2 84.0 90.8 78.7 2,590 3,844 4,465 3.633 These show the highest yield of grain with an irrigation of 20 inches; more than this quantity of water decreased the yield, and with as much as 40 inches of water there was slightly less grain than with 5 inches. 'Bulletin No. 154 Utah Experiment Station. Dry Farming. Since there are many million acres of land in the arid and semi-arid regions of the West where the precipitation is limited or its distribution restricted to certain months in the year; and since in many districts irrigation is not obtainable, not feasible, or limited, dry- farming is of necessity practiced on a large scale. Dry-farming is a system of agriculture in which every possible means is used to store and conserve the scant rainfall and to increase the availability of plant-food. (Fig. 32) It would be well indeed if farming, according to this definition, were done in regions other than those known as arid. Selection of Farm. The selection of a dry farm is of the utmost importance. Several factors should be given care- ful thought before a selection is made. 46 THE MANAGEMENT OF THE SOIL (1) Home. The question arises, "Is this place suitable for a home?" While practicing farming of any sort, it is necessary to live. If water cannot be obtained for cooking purposes and to quench the thirst of man and beast, with- out hauling it long distances, if a little water cannot be secured to encourage the growth of fruit trees and vege- tables, so that a wholesome diet and a breath of shade may be afforded, then that is not the place for a home and hence is not suitable for a successful farm. (2) Rainfall. If the yearly precipitation does not equal 10-12 inches, success can hardly be expected. The amount of rainfall is not the only factor to be considered. The rate of evaporation may be high, or the water capacity of the soil low, or the distribution unfavorable. Some localities have a high precipitation during certain months and little or none in others, while other places have a low rainfall distributed throughout the year. Some localities have most of the rainfall during the spring or early summer months, and some have considerable precipitation during the winter. Rain falling in late summer, after crops have been matured, is probably of less value than that falling at any other time. The rainfall often varies with the elevation. The rainfall in the Snake River plains, Idaho, is from ten to thirteen inches, but at high elevations it is greater than in the valleys, the snow fall being heavier on the mountains. The warm Chinook winds often melt a light snow and the water runs off when the ground is frozen. (4) Climate. The length of the growing period varies with the elevation as well as with the latitude. Late spring and early fall frosts often cause serious damage or the loss of an entire crop; and these factors necessarily limit the number and kinds of crops to be grown where they prevail. The cool nights, even without frost, cause a poor development of such crops as corn and sorghum, and make the maturity of others impossible. The climate therefore governs not only the length of the growing period or the time between frosts, but determines the kind of crops which can be successfully grown. (5) Character of Soil. Samples of the soil taken from various places over the farm in prospect should be ex- MANAGEMENT 47 amined. Borings should be m'ade with an auger to ascer- tain the character of the soil, its depth, texture, and free- dom from injurious alkali. The presence of alkali as well as the fertility of the soil may be determined largely by the amount and character of the native vegetation. Grease-wood and salt weeds indicate alkaline soils; and samples of the soil should be sent to the state experiment station for chemical analysis. (See Exercise 6.) Scant vegetation indicates poor fertility or limited moisture. Mountain valleys consist for the most part of alluvial soils formed by the moun- tain wash and are often very deep. The soil of the plains some distance from the mountains may be very fine, wind-blown material and of less depth. The water-holding capacity of a soil ne- cessarily requires con- siderable depth, since a shallow soil can not hold enough water to sustain growing crops throughout a rainless summer. The texture of the soil also is a determin- ing factor in its water- holding capacity. Coarse gravelly soil has a low capacity for holding water while a soilof fine texture has pjc. 33. Soil Containing Gkavel a high capacity. (See Streaks Experiment 4.) In Not good for dry-farming. Why? 48 THE MANAGEMENT OF THE SOIL some localities small areas of gravel are found. If the gravel streak is within a few feet of the surface (Fig. 33) , dry-farming can not be successful, since it prevents the capillary rise of the water which has passed below its depth. Gravel does not hold water as clay does, and should not be selected unless it contains a large per cent of soil mixed with it. In some sections a limestone hard-pan lies below the surface. This is due to the action of the rainfall which penetrates the soil to approximately the same depth from year to year. Where lime is abundant in the soil, some of it is dissolved and washed down by the rainfall each year. This results, after long periods of time, in a layer of cal- carious material at the depth to which the average annual rainfall has penetrated. Where the soil is poor in lime, the fine particles of soil are washed down and form a "clayey" hard-pan. If this is a number of feet below the surface, it does little harm, but if it is close to the surface, it is very detrimental since it prevents the water from passing below it and thus from being stored in the soil for the use of the crop. In short, the soil should be deep enough and fine enough to hold and store all the rainfall and should not contain alkali to an injurious extent. Many new soils in dry-farming territories are deficient in humus, since there is not sufficient moisture in the soil to rot much organic matter. Small quantities of barn and green manure should be applied when the soil is moist enough to rot it. Equipment for Dry-farming. It is necessary to use large m.achinery in order to do quick work on a dry farm. A delay of one or two days may mean failiu'e. Large machinery necessitates a tractor or enough horse power to run it. A five-horse team may be considered the minimum unit of power on a half-section of land. It is not economy to feed more horses than can be kept at work throughout the year. A medium number kept busy during the year by proper division and management of the work pays best. A dry farm should have wagons, a mold-board plow, a MANAGEMENT 49 spike-tooth, spring-tooth, and a double section disk har- row, cultivators, drill, a header or combine, a manure- spreader, and a corrugated roller. Preparing the Land. If much of the land is covered with native sage brush, dragging several ways with heavy steel rails is quite a satisfactory method of clearing. The brush thus broken off should be raked into windrows and burned. The soil should be plowed from five to seven or eight inches deep, the depth varying with the soil. A light soil may require seven or eight inches breaking. But on heavy or tough sods, the furrow slice is hard to work down flat and to pack against the moist earth below. Here one should use a plow which leaves a flat furrow-bottom and turns the furrow-slice flat. The principle of more importance than any other in dry -farming is that the proper thing must be done at the proper time; and the proper time is when proper conditions are present. To disregard this fundamental principle is to invite failure. The time to break the land, then, is when it is in proper condition to be broken, and when conditions are likely to follow which will insure the storing of moist- ure. If the ground is not too hard and the precipitation is distributed through the winter months in the form of snow, the ground should be broken in the fall, the furrow- slices turned flat, and the surface left rough to absorb the moisture throughout the winter. Some experiment stations recommend leaving the ground fallow for one year in order that suflB.cient moisture to insm-e a crop may be stored in the soil. The fact that the soil is new does not necessarily mean that there is already plenty of moisture ; for the ground has been com- pact and much of the rainfall has consequently run off or been evaporated and most of the remainder has been used by native vegetation. Other experiment stations advise spring breaking of the land, claiming that it is then in better condition to be plowed. This, of course, applies to localities where the greater amount of rainfall is in the spring and early summer. The ground being in good 50 THE MANAGEMENT OP THE SOIL condition, far less labor of horse and man is required for spring plowing than for breaking in the fall when the ground is dry; and the moisture conditions cause the sod turned under to rot more readily. Tilling the Soil. If the sod is broken in the spring, the plow should be followed by the corrugated roller to pack the furrow-slices against the moist earth below, so the capillary rise of water will not be broken. A two or three- inch mulch should then be made with the harrow and this should be re-formed after each rain or at intervals during the spring and summer to conserve moisture and to destroy weeds. This latter point is one not to be neg- lected. Weeds take up an immense amount of water from the soil. (See Exercise 3, Amount of Water Used by Weed.) A crop of weeds uses as much water out of the soil as a crop of grain. "Swat" the weeds! The com- pacting and mulching should be done as soon as the furrow -slice is dry enough, as the surface mulch will pre- vent great loss of water by evaporation. (See Fig. 23.) The land may be sown to winter wheat the first fall after spring breaking and summer fallowing. If there is sufficient moisture and a good mulch, re-plowing will not be needed the first fall ; but at the end of the second year when the sod has become rotted, plowing is necessary again. This should be slightly deeper than the depth of first breaking to establish a deep seed-bed. SuflBcient surface cultivation should follow the plow to insure a seed-bed firm below and loose and fine on top. Disking the stubble should follow immediately after cutting the wheat to check evaporation, thus conserving any moisture remaining in the soil and killing the weeds. Disking also mixes the straw with the soil and makes plowing much easier. When most of the precipitation falls in the winter, fall plowing and alternate cropping and fallowing of the land, thus storing the rainfall of two years to get one crop, has given best results. Where the ground is too dry and hard for fall plowing and the rainy season is in the spring, early spring plowing MANAGEMENT 51 and summer fallowing make a good preparation for the sowing of winter wheat. For spring crops, fall plowing is generally more satisfactory, as it gives the ground time to settle. If the ground must be spring-plowed, it is very important that it be compacted and mulched at once by the corrugated roller (Fig. 23) or the disk harrow set straight. Soils which blow readily can be better handled in strips thirty or forty yards wide, alternately fallowing and cropping the strips. Disking and stubbling-in the seed is a good way to prevent the blowing of the soil. Con- siderable stubble should be worked into the surface before plowing and even then the plowing needs to be shallow until the straw and soil are well mixed. Where a considerable portion of the rainfall is in the growing period, the growing of a light inter-tilled crop like corn in the summer and the sowing of winter wheat in the fall has given good results. Cropping the Dry-fann. Crops should be selected which fit the conditions in which they are to be grown. Limited rainfall and time of distribution, short growing period, low temperature, especially at night, conservation of soil- fertility and means of marketing are some of the condi- tions to be considered. In general, the crops for the dry- farm, then, must be drought and frost-resisting, early maturing, and not too heavy for the available food supply, or rather for the water supply; for food supply, however abundant, is available only in the presence of water. Early planting, whether in spring or fall, is recom- mended. In the spring, it is necessary to get the crop started as early as possible to insure early maturity. This enables the crop to be well along before the summer drought catches it, and to escape the late summer and early fall frosts. Early fall sowing is needful to get the growth started before cold weather. Sowing should be done, however, when there is enough moisture to germinate the seed and to start the growth of the crop. The time varies from the latter part of August to the latter part of 52 THE MANAGEMENT OF THE SOIL September, or in low altitudes even to the first of October. The seed should be planted deep enough to reach moisture to germinate it; this can be done by drilling it in. It is also important in dry-farming to plant the seed thinly so there will not be more plants than the supply of moisture will support. Drought and frost resistant varieties of grain are being developed and systems of rotation gradu- ally worked out so that a permanent and profitable dry- farming agricultural system will soon be assured. Supplementary Irrigation. Since only a fraction of the water necessary to irrigate the arid sections of the coun- try is available, a large part of the country must be reclaimed by dry-farming. It wiU evidently need to be practiced on a large scale to be made profitable, but it has already been proved that it can be made suc- cessful. The dry farm, however, must have suitable water for the house and stock. This, in many regions, may be obtained from deeply bored wells. Water could be pumped from these wells by gasoline or electric engines for the use of house, barnyard, and garden without great expense. Even this much water would make possible an inhabitable home, with growing trees to afl'ord fruit and shade, as well as a vegetable garden which would add much to health and contentment. In some regions the development of springs or the storing of the "run-off" throughout the year in reservoirs and cisterns would furnish a sufficient supply of water for home purposes. Better management and less waste of the water now used for irrigation would naturally help largely to solve this problem in some regions. PROBLEMS 1. a) What kinds of soil need drainage? b) How could you tell that a soil needs drainage? 2. Explain how the available water-supply is increased by drainage.- MANAGEMENT 53 8. a) Explain the effect of drainage upon soil-ventila- tion, b) Upon the temperature of the soil, c) Upon soil organisms. 4. a) Explain the effect of drainage upon the erosion of the surface soil, b) Upon the winter killing of plants. 5. How may accumulations of alkali on irrigated land be prevented.? How removed? 6. Make a summary of the effects of drainage. 7. In your opinion which is the less expensive type of drain? Upon what reasons is this opinion based? 8. Should drains be closer together on a sandy open soil, or upon a heavy clay soil? Why? 9. Upon what does the size of the tile needed depend? Which is usually more effective, the short or the long tile? Why? 10. What determines the depth needed for a drain? Which drains the wider area, a deep drain or a shallow one? Why? 11. Outline the subject of drainage and write an essay upon it. 12. What does tillage include? 13. a) How can tillage increase the supply of soil mois- ture? b) Name two ways in which it conserves soil moisture. 14. Name four points to be considered in determining the kind of tillage. State four advantages which may be gained by fall-plowing. 15. Discuss depth of plowing. 16. What points should be considered in determining the type of plow to be used? 17. How would you avoid the evaporation of moistm-e and the formation of clods after plowing? 18. a) What effect does sub-surface packing have upon the soil? b) With what implement is it done, c) When is it advantageous? 19. What is meant by "blind" cultivation? 20. How soon after irrigation should the soil be culti- vated? Why? Does the mulch need renewing at other times? Explain. 21. If you were planning to irrigate a farm, what conditions would you consider? 54 THE MANAGEMENT OF THE SOIL 22. How would you decrease the deposits of alkali salts on irrigated land? 23. Which are usually more advantageous, frequent light irrigations, or heavy, less frequent ones? Why? What bearing upon this question has the character of the soil? 24. What points should be considered in determining the system of irrigation to be used on a given farm? 25. Make a plan (diagram) for irrigating a field, indi- cating or stating all points considered. 26. Outline the subject of dry-farming, bringing in all the points which you think necessary to be considered. Write an essay fully covering this outline. 27. What factors would guide you in selecting a dry farm? FACTORS OF SOIL FERTILITY A fertile soil is one which will supply plants with needed food. Chemical analysis has shown that plants are built up of various elements. Essentials of Plant Food. Those thought to be essential are nitrogen, oxygen, hydrogen, carbon, potas- sium, phosphorus, calcium, iron, sulphur, and magnesium. Silicon, chlorine and sodium are also found in plants but their use is not fully understood, and plants have been grown to maturity without these. Food Elements Derived from Air and Water. (Fig. 34.) In green plants the leaves take up carbon dioxide (CO2) from the air and break it up into the elements, carbon and <7' Portion of green plant obfa/ned from (aJ Water CbJ/iir (dSoil Fig. 34 oxygen. Nearly one-half of the dry matter of the plant is carbon. It has been proved that greeri plants derive all of their carbon from the atmosphere in the form of carbon dioxide, which is absorbed by the leaves in the pure sunlight. Fungous plants, such as mushrooms, which have no green leaves, cannot thus obtain food but get it from decomposing organic matter. The carbon taken in from carbon dioxide by the leaves unites with the water and with the inorganic material taken in by the roots. By thus uniting, it forms many 56 THE MANAGEMENT OF THE SOIL compounds such as carbohydrates, fats, and proteins. The greater part of the oxygen from the carbon dioxide is given off into the air. Carbohydrates contain carbon with hydrogen and oxygen in the proportion found in water. Vegetable fats contain much carbon and hydrogen with but little oxygen. Proteins contain carbon, hydrogen, oxygen, and nitrogen and sometimes phosphorus and sulphur. The air is one four-hundredth of one per cent carbon dioxide, but the supply of air is so great that it is esti- mated that there are twenty-eight tons of carbon dioxide above every acre of ground. The amount taken up by the plants is offset largely by that given off by animals in breathing so that there is always an abundant supply in the air. Crops are unable to appropriate carbon from the soil. Oxygen forms a large part of many compounds com- posing plants. It is derived from the carbon dioxide taken by the leaves from the air and from the water taken by the roots from the soil. As carbon dioxide is eight-elevenths oxygen and water is eight-ninths oxygen, one can form some idea of the value of oxygen to the plant. Forty-six per cent of a grain of corn is oxygen, while hydrogen, the other element supplied by water, constitutes sixty-four per cent of the kernel of corn. According to Hopkins, 97^^ per cent of the corn kernel consists of the three elements carbon, oxygen, and hydrogen. All that is needed to supply this 973^ per cent is an abundant supply of air and water. The former is supplied without even a thought from us, and the latter is given us if we but conserve it. Food Elements Derived from the Soil. The other ele- ments must be supplied by the soil. Every crop that is grown takes a certaiji amount of these elements from the soil, but it has been discovered that it is necessary to replace but three of them, phosphorus, potassium, and nitrogen. Phosphorus. The amount of phosphorus (usually varying from .02 per cent to .15 per cent) in the soil is FACTORS OF SOIL FERTILITY 57 small compared with that of potassium or with the require- ments of phosphorus for large crops for a number of years in succession. Sufficient available phosphorus is apt to be lacking upon marsh soils* very sandy soils, and upon worn, dry loam soils. Since the amount of phosphorus is small in comparison with crop requirements, it behooves every farmer to guard against its loss. Phosphorus is lost from the soil by erosion. The clay and silt of the soil are richest in phosphorus and this is the part most readily washed out by heavy rains, espe- cially on sloping lands. Fortunately, most of the phos- phorus naturally present is in an insoluble form and so is not lost by leaching. However, when there is much organic matter in the soil, it renders the phosphorus soluble and then it may be lost by leaching. Phosphorus is also lost from the soil by the removal of farm products. The greater part of it is removed in the grain of cereals. But a large percentage of it is contained in the straw or stalks; so that even the farmer who sells his grain may conserve a considerable amount of phosphorus by plowing under the stalks. The farmer who feeds his crops to animals on his farm can conserve a much larger per- centage; for by proper management, about three-fourths of the phosphorus may be returned to the soil in manure. The stock farmer or dairy farmer often finds it necessary to buy feed for his stock. If the manure be properly taken care of and applied to the soil (see Fig. 41), it may return as much'phosphorus or more, if much feed is bought, than the amount removed by his crops. Bran and other con- centrates are especially rich in phosphorus. The phos- phorus actually removed from the stock farm should be chiefly in the bones of animals sold. However, many farms must be grain farms, else where should we obtain our bread? It would be much more difficult to live by meat alone than by bread alone. The grain farmer must, then, find a way to restore to his soil the phosphorus removed by his crops. This is the one element which he must purchase and return to the common soil. An abundant supply of phosphorus makes possible the growth of legumes which, when necessary, secure nitrogen 58 THE MANAGEMENT OF THE SOIL from the air and add it to the soil. If decaying organic matter is furnished from the residue of crops, and from manure made from clover hay or pasture, it makes avail- able the supply of potassium and other elements so abundant in the soil, as well as the less abundant native phosphorus, for the phosphorus in the soil often exists as the insoluble phosphates of iron or aluminum. Especially is this true of the phosphorus in a soil which is deficient in lime, hence it is important that a soil be well supplied with lime and with decaying organic matter ; for the carbon dioxide thus set free in the soil moisture acts upon the insoluble phosphates, rendering them soluble. The bones of animals sold furnish a fertilizer rich in phosphorus. This is known as bone meal, and is made from the scraps which cannot be used in the manufacture of buttons and knife-handles, so that only about one- tenth of the bones sold in farm animals ever reaches the farm again as fertilizer. There are two kinds of bone meal: raw bone meal and steamed bone meal. Since the steamed bones can be ground to a powder and the steam- ing removes the fat, allowing them to decay more rapidly, they are considered much the more valuable as fertilizer. This, with the manure, would restore the phosphorus removed from a stock farm. Fertilizers from mineral phosphates are also to be obtained. Some of the important phosphate beds are in Tennessee, Florida, and South Carolina. There are also new beds of phosphorus in southern Idaho and northern Utah under control of the government federal reserves of phosphate lands. The total output of our phosphate beds would be required to replace the phosphorus re- moved from our farms by our corn crop alone, yet quanti- ties of it are being exported. American farmers should use this product at home, lest the soil be completely im- poverished by the continual removal of its limited supply of phosphorus and by putting none back. This mineral or rock phosphate is sold as fertilizer under the name of "floats." This is comparatively inexpensive. It is of little immediate value unless used in connection with organic matter such as stable manure or green manure from a FACTORS OF SOIL FERTILITY 59 plowed-under crop. It is highly recommended as an absorbent in stables, as it thus becomes immediately mixed with the manure. (Fig. 35.) The carbon dioxide from the decaying matter renders the phosphate available. Another form of phosphorus fertilizer is that known as acid phosphate which is manufactured from natural or "raw rock phosphate" and sulphuric acid; thus the phos- phate is rendered soluble and hence immediately available COMPARATIVE YIELDS ON HEAVY CLAY 50IL5 CLOVER HAY iNCRtASE: 43 Per Cent iNCRCAse 47 PER CENT POTATOES MAN U RE r-lANURE AND ROC h PHOSPHATE Fig. 35. Advantage of Adding Phosphate to Manure. Heavy clay soils respond quickly to the application of rock phosphate supplementing manure. to plants. This may be used by the grain farmer who has not a sufficient supply of stable manure, though it is much more expensive than the raw rock phosphate which he might use with green manuring. While it is true that reactions in the soil render the solu- ble phosphate insoluble in a short time, it is nevertheless important that it be applied in a soluble form or in con- nection with organic matter which renders it soluble, so as to insure its distribution by the soil water before it becomes fixed. (2) Potassium. The amount of potassium in most soils is large and, if conditions exist for making it available, it is not necessary to apply potassium fertilizers. Plenty of 60 THE MANAGEMENT OF THE SOIL humus and proper tillage facilitate the bacterial activities which render plant-food soluble and crops are furnished an abundant supply of potassium. Stable compost in good condition not only supplies this humus but each ton contains approximately ten pounds of potassium. However, some poor light soils and many peaty soils are lacking in potassium and an application of kainit, potassium chloride or potassium sulphate is to be advo- cated. Potassium is useful in building up worn out soils, since it contributes materially to the growth of nitrogen- gathering legumes, so important for this purpose. It is particularly beneficial to root and fruit crops. The sources of commercial potassium are the German mines, salts obtained from the evaporation of sea water, as has been done in southern France and western America, and wood ashes. Recently attention has been directed to potassium in sea-weeds. But, though one ton of dried sea-weed may contain three hundred pounds of potassium, its production as a commercial product has not yet been accomplished. Before the war most of the 200,000 tons of potash used in the United States was obtained from German mines, where the mineral occurs in a form similar to that of rock salt. It was brought over as ballast in the holds of ships. America furnished a comparatively small amount obtained by evaporation from the water of lakes rich in potash salts. Now, America buys no potash from Germany, nor does she need to do so; for many factories are springing up to make it from the waters of her own rich lakes. It is said that Nebraska will furnish more potash this year, and of a better grade, than Germany ever furnished the United States in any one year. There are also important factories at Searles Lake, California, and at Salt Lake, Utah; also at Alunite, Utah, where it is made from the mineral Alunite. The principal fertilizers used are kainit, potas- sium chloride and potassium sulphate. Kainit contains only ten or twelve per cent of potassium, while commercial potassium chloride contains about forty-two per cent and the sulphate, about forty-three per cent of potassium. So in kainit, which appears a cheaper fertilizer, the actual FACTORS OF SOIL FERTILITY 61 potash costs more than it does in the more concentrated forms. Both the chloride and the sulphate are readily available to crops but the chloride is somewhat injurious to potatoes and sugar beets. Chloride should not be applied immediately before or after seeding. If applied in the fall the potassium will be fixed in the soil and the chlorine washed away, but it carries with it a portion of the lime of the soil. Continued applications of the chloride may therefore render the soil acid and occasional applications of lime will be necessary. For this reason as well as on account of the fact that the sulphate is not injurious to any crop, it is cheaper and preferable for continued use. The amount of potassium in wood ashes varies with the kind of wood, the intensity of the heat when forming, and their subsequent protection from water, as they are very soluble and leach readily. Ordinary unleached wood ashes contain about five per cent of potassium, fifty per cent of calcium carbonate, and .5 per cent of phosphorus. On most soils, they are more likely to be valuable for their lime than for their potassium content, and when applied at the rate of a ton or more per acre, even the phosphorus added is more than that contained in two or three hundred pounds of complete commercial fertilizers. Ashes also improve the physical condition of the soil. All wood ashes produced on the farm should be protected from leaching and used, but the cost is so great that they cannot often be bought to advantage. Coal ashes are of no particular value as a fertilizer. (3) Nitrogen. Although nitrogen is required in small quantities, seldom equaling three per cent of the dry matter, or six-tenths of the green plant, it is an important plant-food. It promotes vegetable growth and is an essen- tial element in the green and woody parts of plants. An important commercial fertilizer supplying nitrogen is sodium nitrate, obtained from the great nitrate beds of Chile and often spoken of as Chile saltpeter. Sodium ni- trate contains fifteen per cent of nitrogen in a soluble form, immediately available as plant-food; being a nitrate, it requires no change of form to render it available. Since 62 THE MANAGEMENT OF THE SOIL it is soluble, it will readily leach from the soil and should be used when plants can take it up at once and never put upon bare ground in the fall. For crops which require short periods of growth like the truck garden, sodium nitrate will be beneficial. Long continued or too abundant use of this fertilizer injures the soil structure, as it has a tendency to floculate or break down the aggregation of soil particles, tending to produce a puddled condition, particularly in a clay soil. To prevent this, alternate the application of sodium nitrate with an application of stable manure or green manure. Ammonium sulphate is a by-product in the manufacture of coke and gas. It is soluble in water, but it must be changed to a nitrate by the nitrifying bacteria before it is available as plant-food. This change is readily effected if plenty of lime is present in the soil. If the use of the sulphate is long continued, an occasional application of lime may be necessary as it tends to render the soil acid. The sulphate should not be applied in the fall, as there would be considerable loss by leaching. Nitrogen, from animal sources, may be obtained as dried blood (a good quality of red blood supplies about f ovu-teen per cent of nitrogen) , as tankage, containing four to twelve per cent, as hoof meal, a low-grade fertilizer which is a by-product of glue factories, and as fish-scrap meal, made largely from menhaden, a fish caught along the Atlantic coast. The oil is extracted and the remainder dried and ground. It contains about eight per cent of phosphorus. These animal products must be changed by bacteria before they can be used by crops. They may be profitably applied in the fall, as they are more slowly available than the nitrate and sulphate. Or, if the crop is one like corn, which requires the whole season for its growth, many farmers apply the immediately available nitrate, the quickly available sulphate, and the slowly available animal fertilizers at the same time, giving continual results. The artificial fixation of the nitrogen by a practical method has been recently accomplished in the manu- FACTORS OF SOIL FERTILITY 63 facture of calcium cyanamid, and of calcium nitrate. There is now a calcium cyanamid factory at Niagara Falls, but the supply of these fertilizers is as yet extremely limited. Commercial Fertilizers. The solubility, and thus the availability, as well as the percentage of the fertilizing ingredients should be known before buying commercial fertilizers. Analysis by the state experiment station of the fertilizers on the market has proved that the high grade fertilizers fiu-nish the actual nitrogen, phosphorus, and potash at less cost per pound than do the low grade or cheap fertilizers, since the high grade contain a so much larger percentage of the real fertilizing material. The cost of handling the low grade is also much greater. Home Mixing of Fertilizers. This plan is much to be preferred to buying the so-called complete fertilizers. They may be mixed with a shovel upon a barn or granary floor and then run through a screen or sieve to free the mixture from lumps. The raw materials cost less and there is no useless material to pay for. But of far more value than the item of expense is the fact that home- mixing gives the farmer a chance to know exactly what he is applying to his soil. The fertilizer should be evenly distributed over the field. For this purpose there are now attachments for drills and planters, also broad-casting machines which uniformly distribute the fertilizer, per- mitting it to be harrowed in before planting the seed. Acid in Soils. Acid is detrimental to the fertility of soils. It leads to the exhaustion of phosphorus and calcium. It favors the growth of certain weeds (Fig. 36) among which are sheep sorrel, sour sorrel, corn spurry, horse-tail rush bluets, and sedges. It is injurious to the growth of such important leguminous plants as alfalfa, medium red clover, and sweet clover. The bacteria which form nodules on the roots of these plants, when nitrogen is not abundant in the soil, in some way use the nitrogen in the air in building up compounds which the plpnts require. These nitrogen fixing bacteria do not flourish in acid soils. 64 THE MANAGEMENT OF THE SOIL Fig. 36. Common Weeds Which Indicate Soil Acidity Horse-tail rush, two forms on the left; sheep sorrell on the right (one-fourth natural size). Fields iiiested with these weeds are very likely to have acid soil. How would you remedy it? FACTORS OF SOIL FERTILITY 65 Acidity in soil is often detected by the weeds growing upon it. Though the above-mentioned weeds may some- times be found in soils supplied with lime, they thrive best on acid soil. It may be tested for acid with litmus paper. Exercise 7. Litmus Paper Test for Acid or Alkali. (1) Secure fresh neutral litmus paper, or results will not be satisfactory. (2) Obtain the sample of soil from a place representing the field (or take a sample from each of several places) by the use of a spade digging a hole six inches deep leaving a vertical side. From the full depth of this vertical side take a one-inch slice of soil. Place it in a clean paper, and mix thoroughly with a clean garden trowel. (3) If the soil is moist, form it into a com- pact mass or ball, using the trowel. Make a gash in the mass and insert for an inch a strip of the fresh litmus paper and allow it to remain for five or ten minutes (not longer) . Care should be taken not to touch the moist litmus paper with the fingers, as the perspiration may be acid. If the color of the litmus paper, when taken out and dried, is a distinct pink or red, the soil is acid; if the color is changed to blue, the soil is alkaline. In either case, if the indications are decisive, the soil should be subjected to chemical analysis. (4) If the sample of soil is dry, mix it thoroughly and take three or four tablespoonfuls of it and moisten it sufficiently to be made into a ball and proceed as in (3). Distilled water should be used if possible; if not, then clean rain water which has itself been tested with litmus paper and proved to be neutral; that is, the color of the litmus was not changed to red, indicating acid, nor to blue, indicating alkali in the water. Lime for Acid Soils. Lime not only neutralizes the acid condition of the soil, thereby encouraging the develop- ment of nitrifying bacteria and hence the growth of valu- able legumes, but by its caustic properties it tends to break down humus and, by chemically changing plant- food (for example, potassium and phosphorus) renders them available. It is for this reason, however, that its continued use is not advised. For, while it increases the present crop, in time it renders the land less fertile unless the supply of manure and other fertilizers is replenished. Lime improves the physical condition of the soil. It tends to make a clay soil more porous and mellow, hence it becomes more friable (crumbly) and less liable to puddle and both rain and air are permitted to enter the soil more freely. On the other hand, by cementing the loose particles of sand together, lime renders a sandy soil more compact, and capable of retaining greater quantities of water. 66 THE MANAGEMENT OF THE SOIL The kind of lime to use depends upon the kind of soil to which it is to be applied. Freshlj' slaked lime might be advisable on swampy or peaty land; but owing to its caustic properties it is usually less desirable than finely ground limestone which is the best and most economical form to use when obtainable. It should be evenly applied with a lime-spreader (Fig. 37) upon plowed ground and preferably in the fall. Two or three tons of limestone may Fig. 37. Lime Spreader be applied to the acre, but it is needed but once in a four- year crop rotation. It should not be applied at the same time with either manure or phosphorus. Soils may be deficient in lime from its absence in the rock from which they were formed, or they may become acid by continual cropping or by leaching. In humid regions the rain washes the lime away and the soil tends to become acid; while in arid regions the soil is likely to become alkaline. It should be remembered that (unless soils are in need FACTORS OF SOIL FERTILITY 67 of calcium) lime is not a direct fertilizer. It does not supply plant-food, but it only unlocks that which is present in the soil and aids legumes in securing nitrogen from the air, so that a system of crop rotation, manuring, green manuring and, in some cases, of artificial fertilizing must be maintained if the land is to be permanently benefited. Farm Manure. Too much cannot be said as to the importance of saving and using the manure on the farm. ^ ^E^wHCL^' "' ^^M^ ^B^^^h^HBhI^H ■M^^# ^^^PmH^^HHH^HD^Ih lHi^HK«ii&ui£l * ''i^dHJ H^huB^hH^HI Fig. 38. Manure vs. No Manure Lewistown Experiment field — Alfalfa. Comparing the value of stable manure with that of com- mercial fertilizers, it is estimated that the manure is worth $27 per head of horses' or mules, $20 per head of cattle, and $8 for every hog on the farm. The total value of this fertilizer produced annually by the farm animals of the country is no less than the enormous sum of $2,461,- 000,000. One can scarcely conceive of the result of placing two and one-half billion dollars' worth of fertilizer on the farms of our country. The soil would not simply be enriched with plant food (Fig. 38) as it is by the applica- tion of commercial fertilizers, but the improvement in the tilth and the water-holding capacity of the soil would in many places be worth fully as much if not more than the additional fertility afforded. The application of manure results in increased circulation of air in the soil 68 THE MANAGEMENT OF THE SOIL FACTORS OF SOIL FERTILITY 69 and promotes drainage. Manure in the soil tends to in- crease organic acids, which render the soil minerals more easily soluble. The combination of the humus with cer- tain elements renders them available for plant food. It stimulates the growth of soil organisms and increases nitrification. It stimulates root development and thus has an indirect fertilizing value. Its slow decomposition makes it the most lasting of all fertilizers. Fig. 40. Mancjee Loader — True Conservation Where many cattle or hogs are fed a covered barn- yard paved with concrete is an excellent way of saving the manure. A concrete manure pit is an inexpensive and practical way of saving the nianure from the barn until it can be hauled to the field and applied by the manure- spreader (Fig. 41). It is very important that the manure be kept from leaching and protected from the weather, else much of its fertilizing value is lost. Since fully one- 70 THE MANAGEMENT OF THE SOIL half of the fertilizing value is in the liquid manure, it is important that it be absorbed by bedding, rock phosphate, or gypsum. Open, neglected manure piles endanger the home by polluting the water and furnishing a breeding place for the "typhoid fly." "Safety first" should be the slogan of the farmer and the health of the family should be protected by replacing the old stable-door manure pile with the Fig. 41. Spbe-^ding Manure "Nature's greatest and most universally applicable enricher of the soil." manure pit. Its contents applied to the fields will insure greater crops and prosperity. Help to save the two and one-half billion dollars' worth of fertilizer for the farms of America. Selection of Fertiltzeks. The farmer should first use all ashes and farm manures, animal and vegetable; then, if additional fertilizers are needed, he should use every possible means to ascertain what the soil needs before buying fertilizers. He should write to the Depart- ment of Soils in his own state experiment station to learn whether the soils in his immediate locality have been found to be deficient in any particular element. FACTORS OF SOIL FERTILITY 71 INCREASE IN THE YIELD OF CORN ON VARIOUSLY TREATED PLOTS. AVERAGE FOR THREE YEARS.* Average in- crease in Bushels per Treatments Acre Cowpeas 1-3 Manure 800 pounds 17.0 Manure 800 pounds Cowpeas 22.9 Bone meal 10 pounds Cowpeas 4.7 Bone meal 10 pounds Manure 800 pounds 22 . 1 Bone meal 10 pounds Manure 800 pounds Cowpeas 22 . 2 Potassium sulphate 10 pounds Cowpeas 1.4 Potassium sulphate 10 pounds Manure 800 pounds 16 .4 Bone meal 10 pounds Potassium sulphate 10 pounds Cowpeas 9.8 Bone meal 10 pounds Potassium sulphate 10 pounds Manure 800 pounds 27 . 6 It is worthy of note that nearly two-thirds more corn was produced upon plots to which manure had been applied than was produced upon the untreated plot. It is also true that the full effect of the manure has not yet been obtained, owing to the fact that it exerts an influence throughout a number of years and its effect is cumulative. * Bulletin No. 95 Iowa Experiment Station. 72 THE MANAGEMENT OF THE SOIL Plot Test. Before spending any money and time for fertilizing a large acreage, it is a good plan to find out by actual test just what is needed. A representative plot may be selected near the center of the field. The fertilizer which is thought to be needed may be applied to this plot, one-half of which should be limed in the fall and one-half unlimed. The same care should be given to this plot as to the rest of the field and should be planted in the same kind of a crop. Care should be taken to cultivate the plot in such a way as not to carry the fertilized soil into the general field. The products of the plot and of an equal representative area of the unfertilized field should be weighed or measured and the two compared. PROBLEMS 1. a) How many pounds of carbon dioxide above a 160 acre field.? b) flow is the supply used by plants replaced in the air? 2. Give a short discussion of the plant-food elements derived from air and water. 3. What eifect do heavy rains have upon the phos- phorus supply on sloping lands? Explain. 4. a) In what ways is phosphorus lost from the soil? b) How may it be returned by the stock farmer? By the grain farmer? c) How may the insoluble phosphorus, present in the soil, be rendered available to plants? d) In what form does the grain farmer sell the phosphorus taken from his soil? In what form does the stock farmer sell it? 5. What steps would you take in building up a soil poor in phosphorus? 6. How many pounds more potassium would you get in buying a ton of sulphate of potash, containing 45 per cent potassium, than in a ton of kainit containing 11 per cent? 7. Are leached wood-ashes of value as a potassium fer- tilizer? Explain. 8. Give a short discussion on the importance of nitrogen, and how and when to supply it? FACTORS OF SOIL FERTILITY 73 9. Bring to the laboratory one or more acid-loving plants. 10. What must accompany liming to insure permanent benefit to the soil? 11. Write an essay on "Farm Manures" covering all the facts concerning it given in this book, and any others you may know or can find out. (See Index.) APPARATUS AND MATERIALS FOR SOIL EXERCISES Our plan has been to make the exercises and experi- ments so extremely simple that the apparatus required would be available to every school where Agriculture is taught. Several test tube graduates. One dozen gallon tin pails, or cans with wire or heavy twine for making bails. One cake of parowax. One pair of hand scales for weighing soils. A set of three capillary tubes, of medium, fine, and coarse bore, respectively. A bottle of red ink. One small roll of cotton batting. Soil tubes. Three gauge glass tubes eighteen inches in length, and about three-fourths of an inch in diameter. One small pan. Two soil thermometers. A four-compartment soil bin. Each compartment should be filled in the fall with sand, humus, gravel, and loam respectively. A hammer and a few large spikes. One shallow pan, large enough to contain four gallon cans. One soil auger and one spade. Litmus paper. Gummed labels. A ring stand and three iron clamps. Several small squares of glass. (Old negatives, cleaned, are convenient and very inexpensive.) Two pairs of tinners' shears. One dozen foot-rulers. Four tumblers. One garden trowel. 74 REFERENCES Books. Soil Fertility and Permanent Agriculture, C. G. Hop- kins, Ginn and Co. Soils and Soil Fertility, Whitson and Walster, Webb Pub. Co. The Soil, F. H. King, The Macmillan Co. Soils, I..YON AND FippiN, Thp Macmillan Co. Fertilizers, E. B. Voorhees, The Macmillan Co. The Fertility of the Land, J. P. Roberts, The Mac- millan Co. First Principles of Soil Fertility, Orange Judd Co. Irrigation and Drainage, F. H. King. The Principles of Irrigation Practice, J. A. Widtsoe, The Macmillan Co. Dry Farming, J. A. Widtsoe, The Macmillan Co. Agriculture through the Laboratory and School Garden, Jackson and Daugherty, Orange Judd Co. Bulletins. Soil Alkali Studies, Bui. No. 145, Logan, Utah. The Choice of Crops for Alkali Land, F. B. No. 446, Washington, D. C. Conservation of Soil Resources, F. B. No. 342, Washing- ton, D. C. Farm Drainage, Bui. No. 104, Fayetteville, Arkansas. Tile Drainage on the Farm, F. B. No. 524, Washington, D. C. Farm Drainage, Bui. No. 13, St. Paul, Minnesota. The Right Drain for the Right Place, Bui. No. 229, Madison, Wis. Farm Drainage, Bui. No. 123, Logan, Utah. The Drainage of Irrigated Farms, F. B. No. 805. Crop-growing Suggestions to Dry-Land Farmers, Cir. No. 45, Bozeman, Montana. 75 76 THE MANAGEMENT OF THE SOIL Dry-Farming in Utah, Cir. No. 21, Logan, Utah. Growing Grain on Southern Idaho Dry-Farms, F. B. No. 769, Washington, D. C. Minor Dry-Land Crops at the Nephi Station, Bui. No. 132, Logan, Utah. Dry-Farming in Eastern New Mexico, Bui. No. 104, College Station, New Mexico. Soil Fertility, Cir. No. 157, Urbana, Illinois. Why Illinois Produces only Half a Crop, Cir. No. 193, Illinois. The Fertility of the Soil, Cir. No. 69, Columbia, Missouri. Commercial Fertilizers, 'Bui. No. 173, Burlington, Vermont. Shall We Use Complete Commercial Fertilizers in the Corn Belt? Cir. No. 165, Urbana, Illinois. Factors Influencing the Availability of Rock Phosphate, Research Bui. No. 20, Madison, Wisconsin. Green Manuring and Soil Fertility, Cir. No. 10, Ames, Iowa. Improving Sandy Soils by the Use of Green Manure Crops, Station Bui. No. 120, Corvallis, Oregon. Crimson Clover, Bui. No. 147, Auburn, Alabama. Green Manuring in California, Cir. No. 110, Berkeley, California. Farm Manures, Cir. No. 9, Ames, Iowa. The Physical Improvement of Soils, Cir. No. 82, Urbana, Illinois. Ways of Improving Our Sandy Soils, Bui. No. 204, Madison, Wisconsin. Humus in California Soils, Bui. No. 242, Berkeley, California. Economical Use of Irrigation Water, Bui. No. 140, Corvallis, Oregon. Irrigation and Soil-Moisture Investigations in Western Oregon. Irrigation Investigations, Bui. No. 58, University of Idaho. The Alkali Content of Irrigation Water, Bui. No. 147, Utah. REFERENCES 77 Irrigation and Manuring Studies, Bui. No. 154, Logan, Utah. Practical Information for Beginners in Irrigation, F. B. No. 263, U. S. Dept. of Agriculture, Washington, D. C. Pump Irrigation in Nebraska, Cir. No. 2, Lincoln, Nebraska. Irrigation and Some of Its Problems in Nevada, Better Farming, Vol. 1, No. 9, Reno, Nevada. Irrigation Practice in Montana, Cir. No. 29, Bozeman, Montana. Investigations of Irrigation Pumping Plants, Bui. No. 115, Montana. Testing Soils in Laboratory and Field, Cir. No. 15, Ames, Iowa. Soil Tillage, Extension, Bui. No. 20, St. Paul, Minn. The Roller or Packer, Cir. No. 21, Bozeman, Montana. A Few Notes on Lime for Agricultural Purposes, Cir. No. 13, New Hampshire. Outline of the Relation of the Use of Lime to the Im- provement of the Soil, Cir. No. 25, Cornell, New York. Ground Limestone for Acid Soils, No. 110, Urbana, Illinois. Liming for Tennessee Soils, Bui. No. 97, Knoxville, Tennessee. Soil Acidity and Liming, Bui. No. 230, Madison, Wisconsin. Liming and Lime Requirements of Soil, Bui. No. 306, Wooster, Ohio. AGRICULTURAL PUBLICATIONS Valuable publications upon agricultural subjects may be obtained free, or at a very low cost from the Depart- ment of Agriculture, Washington, D. C, and from your own State Experiment Station. THE UNITED STATES DEPARTMENT OF AGRICULTURE 1. Yearbooks. Valuable. May be obtained through the congressman of your district. 2. Farmers' Bulletins. Excellent. For these address the editor and chief of the Division of Publications, Dept. of Agriculture, Washington, D. C, where they may be obtained free until their supply is exhausted, when they may be obtained from the Superintendent of Documents, Government Printing Office, Washington, D. C, for a small price. 3. Lists of Publications. Write to the editor and chief of the Division of Publications, Dept. of Agriculture, Washington, D. C, and ask for Lists of Publications for free distribution, and Lists of Publications for sale. Also ask to have your name placed on the mailing list to receive the monthly List of Publications. 4. The teacher should write to the Director of States Relations Service and have his name or that of the School placed upon the mailing list to receive the monthly List of Station Publications. When a publication is listed which is desired, it can be obtained by writing to the Director of the State Experiment Station where it is published. (See List of State Experiment Stations on the following page.) 78 ADDRESS LIST OF AGRICULTURAL EXPERI- MENT STATIONS IN THE UNITED STATES AOGUST, 1917 The following list gives the post-office addresses of the Agricultural Experiment Stations in the United States : Alabama — College Station: Auburn. Canebrake Station: Union- town. Tuskegee Station : Tuskegee Institute. Alaska — Sitka. Arizona — Tucson. Arkansas — Fayetteville. California — Berkeley. Colorado — Fort Collins. Connecticut — State Station: New Haven. Storrs Station: Storrs Delaware — Newark. Florida — Gainesville. Georgia — Experiment. Guam, Island of — Guam. Hawaii — Federal Station: Honolulu. Sugar Planters' Station: Hono- lulu. Idaho — Moscow. Illinois — Urbana. Indiana — Lafayette. Iowa — Ames. Kansas — Manhattan. Kentucky — Lexington. Louisiana — State Station: Baton Rouge. Sugar Station: Audubon Park, New Orleans. North Louisiana Station: Cal- houn. Rice Experiment Station: Crowley. Maine — Orono. Martland — College Park. Massachusetts — Amherst. Michigan — East Lansing. Minnesota — University Farm, St. Paul. Mississippi — Agricultural College. Missouri — College Station: Columbia. Fruit Station: Mountain Grove. Montana — Bozeman. Nebraska — Lincoln. Nevada — Reno. New Hampshire — Durham. New Jersey — New Brunswick New Mexico — State College. New York — State Station: Geneva Cornell Station: Ithaca. North Carolina — Raleigh and West Raleigh. North Dakota — Agricultural College. Ohio — Wooster. Oklahoma — Stillwater. Oregon — Corvallis. Pennsylvania — State College. PoKTo Rico — Federal Station: Mayaguez. Rhode Island — Kingston. South Carolina — Clemson College, South Dakota — Brookings. Tennessee — Knoxville. Texas — College Station. Utah — Logan. Vermont — Burlington. Virginia — Blacksburg. Norfolk: Truck Station. Washington — Pullman. West Virginia — Morgantown. Wisconsin — Madison. Wyoming — Laramie. 79 INDEX Acid, injurious to leguminous plants, 63 in soils, 63 lime for, 65 of roots, 6 test for, 65 Air, plant food in, 55 Alfalfa, along irrigating ditches, 41 Alkali, effect of drainage on, 24 excess of, 21, 23 indicated by native plants, 38, 47 _ reclamation of alkali lands, 24 spots in fields, 39 test for, exercise 6, 38 Animals, 7 Apparatus needed, 74 Auger, soil, 38 Bacteria, 23, 6 activities of, 60 not favored by acid soils, 63 Bone meal, 58 Capillary action, 14, 29 lateral. Experiment 8, 44 Carbohydrates, 56 Carbon-dioxid, acts upon lime- stone, 55 in the air, 56 supplies plant food, 55 Chemical action, 5 of the acid of roots, 6 upon minerals, 2 Climate, for dry-farming, 46 Cover crop, 32 Cultivation, following irrigation, 36, 44 following rain, 36 in dry-farming, 50 Decomposition, 2 Disintegration, 2 Disking, for mulch, 35, 50 to prevent blowing of soil, 51 Drainage, effects of, 21 effect, of tile (Fig. 13), 22 favors bacteria, 23 improves soil structure, 21 improves soil ventilation, 22 increases depth of roots, 21, 22 increases temperature, 22 prevents erosion, 23 reduces heaving, 23 removes alkali, 23 increases yield (Fig. 10), 19 need of, 20 undrained land (Fig. 11), 20 value of, 19 Drains, 26 surface, 26 under, or tile, 26 arrangement of, 27 Dry farming, 45 cropping, 50 equipment for, 48 factors considered, 46 preparing the land, 49 tilling the soil, 50 Erosion of Rock, 2 Evaporation, a cooling process, 22 prevented, 30 water lost through, 36 Experiment stations, 79 Fallowing, 49, 50 Fertility of soil, 55 problems, 72 Fertilizers, 57, 63 home mixing of, 63 plot test for, 72 selection of, 70 table showing results of, 71 Fungi, 55 81 82 INDEX Grader, fresno, 41 Grading, for irrigation, 41, 42, 43 Gravel, stratum of, 38, 47 Hard-pan, "clayey," 48 limestone, 48 Harrowing, prevents evaporation, 30 conserves moisture, 32 improves soil structure, 32 in dry-farming, 50 should follow plowing, 35 Humus, definition of, 7 favors bacteria, 60 soil deficient in, 48 supplied by manure, 60 water-holding capacity of, 15 Exercise 4, 16 Hydrogen, essential to plants, 55 Insects, killed by fall plowing, 30 Iron, forms rust, 5 Irrigation, 37 conditions for, 37, 38 cultivation after, 43, 44 over-irrigation, 40, 41, 43 preparation for, 41 results of, table, 45 supplementary to dry-farming, 52 systems of, 42 flooding, 42 furrow, 42, 43 time for, 39 water for, 40 Kainit, 60 Leaf mold, 7 Lime, forms hard-pan, 48 for acid soils, 65 important in soil, 58 not a plant food, 67 spreader, 66 Malaria, 25 Manure, farm, 67 green, with rock phosphate, 59 liquid, 70 loader, 69 pit, 69 renders plant food available, 58 returns phosphorus to soil, 57 spreader, 70 supplies potassium, 60 value of, 67 Mosquitoes, 25 Mulch, depth of, 36 destroyed by absorption of moisture, 36 made by corrugated roller, 33, 34 made by disk, 34 made by harrow, 35 prevents evaporation, 29, 37, 44, 50 should be often reformed, 50 Nitrogen, essential to plants, 55 fixation by calcium cyanamid and calcium nitrate, 63 from ammonium sulphate, 62 from animal sources, 62 from sodium nitrate, 63 Oxygen essential to plants, 55 unites with minerals, 5 Organic agencies, 6 Organic formations, 7 Phosphate, beds, 58 Phosphorus, "floats," 58 in soil, 56 lost from soil, 57 Planting, depth of, 52 time of, 51 Plant-food, essentials of, 55 derived from air and water, 55 derived from soil, 56 Plasticity, 10 Plowing, 30 fall, 30 depth of, 32 in dry farming, 50 spring, 32, 50 subsoil, 34 Potassium, as fertilizer, 59 in wood ashes, 61 sources of, 60 sulphate, 60, 61 Proteins, 56 INDEX 83 Publications, how to secure, 78 Rain, 3 Rainfall, 46 forms limestone hard-pan, 48 References, 75 Rolling, 34 in dry-farming, 50, 51 Roots, acid of, 6 disintegrating rocks, 5 Sage Brush, 49 Seepage, 23, 38, 39 Soil, 19 Agricultural types of, 9 clay, 9 loam, 10 problems, 10 sandy, 9 alluvial, 2 auger, 38, 47 bin, 16 formation of soil, 1 chemical action in, 5 field trip to observe, 7 organic agencies, problems on, 8 temperature, 5 water as a factor in, 2 wind, 5 loess, 6 man's dependence upon (Exer- cise 1), 1 puddled, 10, 30 structure of, 10 Subsoil, 34, 38 Surface area (problem), 5 of clay, 9 Temperature, 9 in soil formation, 5 of soil, 15 of slope, 17 exercise 5, 17 Fig. 9, p. 17 Texture of soil, 9, 10 effect on rise of water, 14 effect on water-holding capacity, 15, 47 Tillage, 28 conserves moisture, 28 destroys weeds, 29 incorporates residues, 29 prepares seed-bed, 28 Tractor, 48 Vegetation, indicates alkaline soil, 47 indicates fertility of soil, 47 indicates need of drainage, 20 protects soil, 6 Water, as plant food, 55 as rain, 3 capillary water, 14 effect of texture on rise of, 15 effect of texture on water-hold- ing capacity, 15 glaciers, 4 gravitational water, 13 importance of, 12 constitutes plant food, 13 ! dissolves plant food, 12 ) given off by plant, 13 i,- in soil formation, 2 lake and stream, 4 transporting and assorting power of, 3 Weeds, along irrigating ditches, 41 destroyed by early fall plowing, 30 use water 13, 50 Wind, 5 Books in A Series of Short Courses In Agriculture By JACKSON AND DAUGHERTY Course I. "THE MANAGEMENT OF THE SOIL." (This book.) Course II. "IMPROVEMENT OF FARM PRODUCTS." Course III. "THE MANAGEMENT OF FARM CROPS." Course IV. "THE MANAGEMENT OF FARM ANIMALS." Course V. "THE COUNTRY HOME." Each course gives the underlying principles of a special phase of the subject of Agriculture. These are practical, teachable books, based on years of actual experience in teaching Agricul- tiire. They are fully illustrated and cloth-bound. Course II will follow soon. You will want it in your September classes. Courses III, IV, and V are in preparation. Address All Orders to C. R. JACKSON, Albion, Idaho, or MRS. L. S. DAUGHERTY, Cameron, Mo.