Transcriber's Note: Minor typographical errors have been corrected without note. Dialect spellings, contractions and discrepancies have been retained.
CROPS AND METHODS FOR SOIL IMPROVEMENT
THE MACMILLAN COMPANY NEW YORK . BOSTON . CHICAGO DALLAS . SAN FRANCISCO
MACMILLAN & CO., Limited LONDON . BOMBAY . CALCUTTA MELBOURNE
THE MACMILLAN CO. OF CANADA, Ltd. TORONTO
CROPS AND METHODS FOR SOIL IMPROVEMENT
ALVA AGEE, M.S.
HEAD OF DEPARTMENT OF AGRICULTURAL EXTENSION ACTING DEAN AND DIRECTOR OF THE SCHOOL OF AGRICULTURE AND EXPERIMENT STATION OF THE PENNSYLVANIA STATE COLLEGE
New York THE MACMILLAN COMPANY 1912
All rights reserved
Copyright, 1912, By THE MACMILLAN COMPANY.
Set up and electrotyped. Published November, 1912.
Norwood Press J. S. Cushing Co.—Berwick & Smith Co. Norwood, Mass., U.S.A.
INTRODUCTION 1-11 In lieu of preface 1 Natural strength of land 2 Plant constituents 2 Organic matter 4 Drainage 6 Lime 7 Crop-rotation 8 Fertilizers 9 Tillage 10 Control of soil moisture 11
THE NEED OF LIME 12-22 The unproductive farm 12 Soil acidity 13 The rational use of lime 14 Where clover is not wanted 16 Determining lime requirement 17 The litmus-paper test 19 A practical test 20 Duration of effect 21
APPLYING LIME 23-35 Forms of lime 23 Definitions 24 The kind to apply 26 The fineness of limestone 27 Hydrated lime 27 Stone-lime 28 Ashes 30 Marl 31 Magnesian lime 31 Amount per acre 32 Time of application 34
ORGANIC MATTER 36-45 Office of organic matter 36 The legumes 38 Storing nitrogen 39 The right bacteria 41 Soil inoculation 42 Method of inoculation 43
THE CLOVERS 46-58 Red clover 46 Clover and acid soils 47 Methods of seeding 48 Fertility value 49 Taking the crops off the land 51 Physical benefit of the roots 52 Used as a green manure 52 When to turn down 53 Mammoth clover 54 Alsike clover 55 Crimson clover 56
ALFALFA 59-70 Adaptation to eastern needs 59 Fertility and feeding value 60 Climate and soil 61 Free use of lime 62 Inoculation 62 Fertilization 63 A clean seed-bed 64 Varieties 65 Clean seed 65 The seeding 66 Seeding in August 67 Subsequent treatment 68
GRASS SODS 71-79 Value of sods 71 Prejudice against timothy 72 Object of sods 74 Seeding with small grain 75 Seeding in rye 76 Good soil conditions 77
GRASS SODS (Continued) 80-89 Seeding in late summer 80 Crops that may precede 81 Preparation 83 The weed seed 84 Summer grasses 85 Sowing the seed 85 Deep covering 86 Seed-mixtures 88
SODS FOR PASTURES 90-97 Permanent pastures 90 Seed-mixtures 91 Blue-grass 91 Timothy 92 Red-top 92 Orchard grass 93 Other seeds 93 Yields and composition of grasses 93 Suggested mixtures for pastures 94 Renewal of permanent pastures 96 Destroying bushes 96 Close grazing 97
THE COWPEA 98-107 A southern legume 98 Characteristics 99 Varieties 99 Fertilizing value 100 Affecting physical condition 101 Planting 101 Inoculation 103 Fertilizers 103 Harvesting with livestock 104 The cowpea for hay 104 As a catch crop 106
OTHER LEGUMES AND CEREAL CATCH CROPS 108-119 The soybean 108 Fertility value 109 Feeding value 109 Varieties 110 The planting 111 Harvesting 112 The Canada pea 113 Vetch 113 Sweet clover 115 Rye as a cover crop 116 When to plow down 117 Buckwheat 118 Oats 119
STABLE MANURE 120-128 Livestock farming 120 The place for cattle 121 Sales off the farm 122 The value of manure 124 The content of manure 125 Relative values 126 Amount of manure 127 Analysis of manure 128
CARE OF STABLE MANURE 129-138 Common source of losses 129 Caring for liquid manure 130 Use of preservatives 131 Spreading as made 132 The covered yard 133 Harmless fermentation 135 Rotted manure 135 Composts 136 Poultry manure 137
THE USE OF STABLE MANURE 139-148 Controlling factors 139 Direct use for corn 140 Effect upon moisture 141 Manure on grass 142 Manure on potatoes 143 When to plow down 144 Heavy applications 144 Reenforcement with minerals 145 Durability of manure 147
CROP-ROTATIONS 149-158 The farm scheme 149 Value of rotation 150 Selection of crops 151 An old succession of crops 152 Corn two years 153 The oat crop 154 Two crops of wheat 154 The clover and timothy 154 Two legumes in the rotation 155 Potatoes after corn 156 A three-years' rotation 157 Grain and clover 158 Potatoes and crimson clover 158
THE NEED OF COMMERCIAL FERTILIZERS 159-170 Loss of plant-food 159 Prejudice against commercial fertilizers 160 Are fertilizers stimulants? 161 Soil analysis 162 Physical analysis 163 The use of nitrogen 164 Phosphoric-acid requirements 165 The need of potash 166 Fertilizer tests 167 Variation in soil 168
COMMERCIAL SOURCES OF PLANT-FOOD 171-187 Acquaintance with terms 171 Nitrate of soda 171 Sulphate of ammonia 178 Dried blood 173 Tankage 174 Fish 175 Animal bone 175 Raw bone 177 Steamed bone 178 Rock-phosphate 178 Acid phosphate 180 Basic slag 183 Muriate of potash 184 Sulphate of potash 185 Kainit 185 Wood-ashes 185 Other fertilizers 186 Salt 186 Coal-ashes 187 Muck 187 Sawdust 187
PURCHASING PLANT-FOOD 188-197 Necessity of purchase 188 Fertilizer control 189 Brand names 191 Statement of analysis 191 Valuation of fertilizers 193 A bit of arithmetic 194 High-grade fertilizers 196
HOME-MIXING OF FERTILIZERS 198-208 The practice of home-mixing 198 Effectiveness of home-mixing 198 Criticisms of home-mixing 199 The filler 202 Ingredients in the mixture 203 Materials that should not be combined 207 Making a good mixture 207 Buying unmixed materials 208
MIXTURES FOR CROPS 209-219 Composition of plant not a guide 209 The multiplication of formulas 209 A few combinations are safest 210 Amount of application 211 Similarity of requirements 213 Maintaining fertility 215 Fertilizer for grass 216 All the nitrogen from clover 218 Method of applying fertilizers 218 An excess of nitrogen 219
TILLAGE 220-229 Desirable physical condition of the soil 220 The breaking-plow 221 Types of plows 221 Subsoiling 223 Time of plowing 223 Method of plowing 224 The disk harrow 225 Cultivation of plants 227 Controlling root-growth 227 Elimination of competition 228 Length of cultivation 229
CONTROL OF SOIL MOISTURE 230-236 Value of water in the soil 230 The soil a reservoir 231 The land-roller 232 The plank-drag 233 The mulch 233 Mulches of foreign material 234 Plowing straw down 235 The summer-fallow 235 The modern fallow 236
DRAINAGE 237-246 Underdrainage 237 Counting the cost 238 Where returns are largest 239 Material for the drains 239 The outlet 240 Locating main and branches 240 The laterals 241 Size of tile 241 Kind of tile 242 The grade 243 Establishing a grade 243 Cutting the trenches 244 Depth of trenches 245 Connections 245 Permanency desired 246
Alfalfa and Corn in Indiana Frontispiece
A Good Crop for a Poor Soil 4
Red Clover on Limed and Unlimed Land 20
Turning down Organic Matter with a Gang Plow 36
Red Clover on the Farm of P. S. Lewis & Son, Pt. Pleasant, W. Va. 51
Alfalfa on the Ohio State University Farm 61
Curing Alfalfa at the Pennsylvania Experiment Station 68
A Heavy Grass Sod in New York 73
Good Pasture Land in Chester County, Pa. 90
Sheep on a New York Farm 96
The Cowpea Seeded at the Last Cultivation of Corn in the Great Kanawha Valley, W. Va. 106
Texas Calves on an Ohio Farm 121
In the Fertile Miami Valley, Ohio 126
Concrete Stable Floors 131
Corn in the Ohio Valley 140
Penn's Valley, Pennsylvania 151
In the Shenandoah Valley 155
Plat Experiments 167
In the Lebanon Valley, Pennsylvania 189
On the Productive Farm of Dr. W. I. Chamberlain in Northwestern Ohio 210
Deep Tillage 222
Making an Earth Mulch in a New York Orchard 233
Drain Tile 239
The Lure of the Country 246
CROPS AND METHODS FOR SOIL IMPROVEMENT
In Lieu of Preface.—This book is not a technical treatise and is designed only to point out the plain, every-day facts in the natural scheme of making and keeping soils productive. It is concerned with the crops, methods, and fertilizers that favor the soil. The viewpoint, all the time, is that of the practical man who wants cash compensation for the intelligent care he gives to his land. The farming that leads into debt, and not in the opposite direction, is poor farming, no matter how well the soil may prosper under such treatment. The maintenance and increase of soil fertility go hand in hand with permanent income for the owner when the science that relates to farming is rightly used. Experiment stations and practical farmers have developed a dependable science within recent years, and there is no jarring of observed facts when we get hold of the simple philosophy of it all.
Natural Strength of Land.—Nearly all profitable farming in this country is based upon the fundamental fact that our lands are storehouses of fertility, and that this reserve of power is essential to a successful agriculture. Most soils, no matter how unproductive their condition to-day, have natural strength that we take into account, either consciously or unconsciously. Some good farm methods came into use thousands of years ago. Experience led to their acceptance. They were adequate only because there was natural strength in the land. Nature stored plant-food in more or less inert form and, as availability has been gained, plants have grown. Our dependence continues.
Plant Constituents.—There are a few technical terms whose use cannot be evaded in the few chapters on the use of lime and fertilizers. A plant will not come to maturity unless it can obtain for its use combinations of ten chemical elements. Agricultural land and the air provide all these elements. If they were in abundance in available forms, there would be no serious soil fertility problem. Some of their names may not interest us. Six or seven of these elements are in such abundance that we do not consider them. A farmer may say that when a dairy cow has luxuriant blue-grass in June, and an abundance of pure water, her wants are fully met. He omits mention of the air because it is never lacking in the field. In the same way the land-owner may forget the necessity of any kind of plant-food in the soil except nitrogen, phosphoric acid, potash, and lime. Probably the lime is very rarely deficient as a food for plants, and will be considered later only as a means of making soils friendly to plant life.
Nitrogen, phosphoric acid, and potash are the three substances that may not be in available form in sufficient amount for a growing crop. The lack may be in all three, or in any two, or in any one, of these plant constituents. The natural strength of the soil includes the small percentage of these materials that may be available, and the relatively large stores that nature has placed in the land in inert form as a provision against waste.
The thin covering of the earth that is known as the soil is disintegrated rock, combined with organic matter. The original rock "weathered," undergoing physical and chemical change. A long period of time was required for this work, and for the mixing and shifting from place to place that have occurred. Organic matter has been a factor in the making of soils, and is in high degree a controlling one in their production of food.
Organic Matter.—Nature is resourceful and is constantly alert to repair the wastes and mistakes of man. We may gain fundamental truth about soil fertility through observance of her methods in restoring land to a fertile condition. Our best success comes only when we work with her. When a soil has been robbed by man, and has been abandoned on account of inability to produce a profitable crop, the first thing nature does is to produce a growth of weeds, bushes, briers, or aught else of which the soil chances to have the seeds. It is nature's effort to restore some organic matter—some humus-making material—to the nearly helpless land. Vegetable matter, rotting on and in the soil, is the life-giving principle. It unlocks a bit of the great store of inert mineral plant-food during its growth and its decay. It is a solvent. The mulch it provides favors the holding of moisture in the soil, and it promotes friendly bacterial action. The productive power of most farming land is proportionate to the amount of organic matter in it. The casual observer, passing by farms, notes the presence or absence of humus-making material by the color and structure of the soil, and safely infers corresponding fertility or poverty. Organic matter is the life of the soil.
A great percentage of the food consumed by Europe and the Americas continues to come out of nature's own stores in the soil, organic and inorganic, without any assistance by man except in respect to selection of seeds, planting, and tillage. The percentage grows less as the store of original supplies grows less and population increases. Our science has broadened as the need has grown greater. We have relatively few acres remaining in the United States that do not require intelligent treatment to insure an adequate supply of available plant-food. The total area that has fallen below the line of profitable productiveness is large. Other areas that never were highly productive must supplement the lands originally fertile in order that human needs may be met.
When soils have been robbed through the greed of man, nature is handicapped in her effort to restore fertility by the absence of the best seeds. Man's intelligent assistance is a necessity. Successful farming involves such assistance of nature that the percentage of vegetable matter in the soil shall be made high and kept high. There must be such selection of plants for this purpose that the organic matter will be rich in fertility, and at the same time their growth must fit into a scheme of crop production that can yield profit to the farmer. Soils produce plants primarily for their own needs. It is a provision of nature to maintain and increase their productive power. The land's share of its products is that part which is necessary to this purpose. Skill in farming provides for this demand of the soil while permitting the removal of a large amount of animal food within the crop-rotation. Lack of skill is responsible for the depleted condition of soils on a majority of our farms. The land's share of the vegetation it has produced has been taken from it in large measure, and no other organic matter has been given it in return. Its mineral store is left inert, and the moisture supply is left uncontrolled. Helplessness results.
Drainage.—Productive soils are in a condition to admit air freely. The presence of air in the soil is as necessary to the changes producing availability of plant-food as it is to the changes essential to life in the human body. A water-logged soil is a worthless one in respect to the production of most valuable plants. The well-being of soil and plants requires that the level of dead water be a considerable distance below the surface.
When a soil has recently grown trees, the rotting stump roots leave cavities in the subsoil that permit the removal of some surplus water, and the rotted wood and leaves that give distinctive character to new land are absorbents of such water. As land becomes older, losing natural means of drainage and the excellent physical condition due to vegetable matter in it, the need of drainage grows greater. The tramping of horses in the bottoms of furrows made by breaking-plows often makes matters worse. The prompt removal of excessive moisture by drains, and preferably by underdrains, is essential to profitable farming in the case of most wet lands. The only exception is the land on which may be grown the grasses that thrive fairly well under moist conditions.
Lime.—The stores of lime in the soil are not stable. The tendency of lime in most of the states between the Missouri River and the Atlantic seaboard is to get out of the soil. There is no evidence that lime is not in sufficient quantity in most soils to feed crops adequately, but within recent years we have learned that vast areas do not contain enough lime in available form to keep the soil from becoming acid. Some soils never were rich in lime, and these are the first to show evidence of acidity. In our limestone areas, however, acid soil conditions are developing year by year, limiting the growth of clover and affecting the yields of other crops.
The situation is a serious one just in so far as men refuse to recognize the facts as they exist, and permit the limiting of crop yields, and consequently of incomes, through the presence of harmful acids. The natural corrective is lime, which combines with the acid and leaves the soil friendly to all plant life and especially to the clovers and other legumes that are necessary to profitable farming. Nature is largely dependent upon man's assistance in the correction of soil acidity.
Crop-rotation.—A good crop-rotation favors high productiveness. One kind of crop paves the way nicely for some other one. The land can be occupied by living plants without any long intermissions. Organic matter can be supplied without the use of an undue portion of the time. The stores of plant-food throughout all the soil are more surely reached by a variety of plants, differing in their habits of root-growth. The injury from disease and insects is kept down to a minimum. There is better distribution of the labor required by the farm, and neglect of crops at critical times is escaped. The maintenance of fertility is dependent much upon the use of a legume that will furnish nitrogen from the air. A permanently successful agriculture in our country must be based upon the use of legumes, and crop-rotations would be demanded for this reason alone if none other existed.
Fertilizers.—When a crop is fed to livestock, and all the manure is returned to the land that produced the crop without loss by leaching or fermentation, there is a return to the land of four fifths of the fertility, and a good form of organic matter is supplied. A portion of the crops cannot be fed upon the farm, or otherwise the human race would have only animal products for food. The welfare of the people demands that a vast amount of the soil's crops be sold from the farms producing them. This brings about a dependence upon the natural stores of plant-food in the soil, which become available slowly, and upon commercial fertilizers.
There has been a disposition on the part of many farmers to regard fertilizers only as stimulants, due to the irrational use of certain materials, but a good commercial fertilizer is a carrier of some or all of the necessary elements that we find in stable manures. They may carry nitrogen, phosphoric acid, or potash,—any one or two or the three,—and the three are the constituents that usually are lacking in available forms in our soils. Examples of the best modern skill in farming may be found in the rational selection and use of commercial fertilizers.
Tillage.—Man's ability to assist nature in the work of production finds a notable illustration in the matter of tillage. Its purpose is to provide right physical condition of the soil for the particular class of plants that should be produced, while destroying the competition of other plants that are for the time only weeds. Most soils become too compact when left unstirred. The air cannot enter freely, plant-roots cannot extend in every direction for food, the water from rains cannot enter easily, there is escape of the moisture in the ground, and weathering of the soil proceeds too slowly. The methods used in plowing, harrowing, and later cultivations fix the productive power of a soil for the season in large measure.
Control of Soil Moisture.—The water in the soil is a consideration that has priority over plant-food in the case of agricultural land. The natural strength of the soil is sufficient to give some return to the farmer in crops if the moisture content is right throughout the season. The plant cannot feed unless water is present; the process of growth ceases in the absence of moisture. One purpose of plowing is to separate the particles of soil to a good depth so that water-holding capacity may be increased. When the soil is compact, it will absorb and hold only a very limited amount of moisture. We harrow deeply to complete the work of the plow, and the roller is used to destroy all cavities of undue size that would admit air too freely and thus rob the land of its water. Later cultivations may be given to continue the effect of the plow in preventing the soil from becoming too compact, but usually should be required only to make a loose mulch that will hold moisture in the ground, and to destroy the weeds that would compete with the planted crop for water, food, and sunshine.
THE NEED OF LIME
The Unproductive Farm.—When a soil expert visits an unproductive farm to determine its needs, he gives his chief attention to four possible factors in his problem: lack of drainage, of lime, of organic matter, and of available plant-food. His first concern regards drainage. If the water from rains is held in the surface by an impervious stratum beneath, it is idle to spend money in other amendments until the difficulty respecting drainage has been overcome. A water-logged soil is helpless. It cannot provide available plant-food, air, and warmth to plants. Under-drainage is urgently demanded when the level of dead water in the soil is near the surface. The area needing drainage is larger than most land-owners believe, and it increases as soils become older. On the other hand, the requirements of lime, organic matter, and available plant-food are so nearly universal, in the case of unproductive land in the eastern half of the United States, that they are here given prior consideration, and drainage is discussed in another place when methods of controlling soil moisture are described. The production of organic matter is so important to depleted soils, and is so dependent upon the absence of soil acidity, that the right use of lime on land claims our first interest.
Soil Acidity.—Lime performs various offices in the soil, but farmers should be concerned chiefly about only one, and that is the destruction of acids and poisons that make the soil unfriendly to most forms of plant life, including the clovers, alfalfa, and other legumes. Lime was put into all soils by nature. Large areas were originally very rich in lime, while other areas of the eastern half of the United States never were well supplied. Within the last ten years it has been definitely determined that a large part of this vast territory has an actual lime deficiency, as measured by its inability to remain alkaline or "sweet." Many of the noted limestone valleys show marked soil acidity. There has been exhaustion of the lime that was in a state available for union with the acids that constantly form in various ways. The area of soil thus deficient grows greater year by year, and it can be only a matter of time when nearly all of the eastern half of this country will have production limited by this deficiency unless applications of lime in some form are made. When owners of soil that remains rich in lime do not accept this statement, no harm results, as their land does not need lime. On the other hand are tens of thousands of land-owners who do not recognize the need of lime that now exists in their soils, and suffer a loss of income which they would attribute to other causes.
Irrational Use of Lime.—Some refusal to accept the facts respecting soil acidity and its means of correction is due to a prejudice that was created by an unwise use of lime in the past. Owners of stiff limestone soils learned in an early day that a heavy application of caustic lime would increase crop production. It caused such flocculation of the fine particles in their stiff soils that physical condition was improved, and it made the organic matter in the soil quickly available as plant-food. The immediate result was greater crop-producing power in the soil, and dependence upon lime as a fertilizer resulted. The vegetable matter was used up, some of the more available mineral plant-food was changed into soluble forms, and in the course of years partial soil exhaustion resulted. The heavy applications of lime, unattended by additions of organic matter in the form of clover sods and stable manure, produced a natural result, but one that was not anticipated by the farmers. The prejudice against the use of lime on land was based on the effects of this irrational practice.
There are land-owners who are not concerned with present-day knowledge regarding soil acidity because they cannot believe that it has any bearing upon the state of their soils. They know that clover sods were easily produced on their land within their remembrance, and that their soils are of limestone origin. As the clovers demand lime, these two facts appear to them final. The failures of the clovers in the last ten or twenty years they incline to attribute to adverse seasons, poor seed, or the prevalence of weed pests. They do not realize that much land passes out of the alkaline class into the acid one every year. The loss of lime is continuous. Exhaustion of the supply capable of combining with the harmful acids finally results, and with the accumulation of acid comes partial clover failure, a deficiency in rich organic matter, a limiting of all crop yields, and an inability to remain in a state of profitable production.
Lime deficiency and its resulting ills would not exist as generally as is now the case if the application of lime to land were not expensive and disagreeable. These are deterrent features of wide influence. There continues hope that the clover will grow successfully, as occasionally occurs in a favorable season, despite the presence of some acid. The limitation of yields of other staple crops is not attributed to the lack of lime, and the proper soil amendment is not given to the land.
Where Clover is not Wanted.—The ability to grow heavy red clover is a practical assurance that the soil's content of lime is sufficiently high. When clover fails on account of a lime deficiency, the work of applying lime may not be escaped by a shift in the farm scheme that permits the elimination of clover. The clover failure is an index of a condition that limits the yields of all staple crops. The lack of lime checks the activity of bacteria whose office it is to prepare plant-food for use. The stable manure or sods decompose less readily and give smaller results. Soil poisons accumulate. Mineral plant-food in the soils becomes available more slowly. Physical condition grows worse.
The limitations of the value of manure and commercial fertilizers applied to land that has a lime deficiency have illustration in an experiment reported by the Cornell station:
The soil was once a fertile loam that had become very poor. A part was given an application of lime, and similar land at its side was left unlimed. The land without lime and fertilizer of any kind made a yield of 1824 pounds of clover hay per acre. A complete fertilizer on the unlimed land made the yield 2235 pounds, and 15 tons of manure on the unlimed land made the yield 2091 pounds.
Where lime had been applied, the unfertilized land yielded 3852 pounds per acre, the fertilized, 4085 pounds, and the manured, 4976 pounds. The manure and fertilizer were nearly inactive in the acid soil. The lime enabled the plants to obtain benefit from the plant-food.
Determining Lime Requirement.—It is wasteful to apply lime on land that does not need it. As has been said, the man who can grow heavy clover sods has assurance that the lime content of his soil is satisfactory. This is a test that has as much practical value as the analysis of a skillful chemist. The owner of such land may dismiss the matter of liming from his attention so far as acidity is concerned, though it is a reasonable expectation that a deficiency will appear at some time in the future. Experience is the basis of such a forecast. Just as coal was stored for the benefit of human beings, so was lime placed in store as a supply for soils when their unstable content would be gone.
The only ones that need be concerned with the question of lime for soils are those who cannot secure good growths of the clovers and other legumes. Putting aside past experience, they should learn whether their soils are now acid. Practical farmers may judge by the character of the vegetation and not fail to be right nine times out of ten. Where land has drainage, and a fairly good amount of available fertility, as evidenced by growths of grass, a failure of red clover leads immediately to a strong suspicion that lime is lacking. If alsike clover grows more readily than the red clover, the probability of acidity grows stronger because the alsike can thrive under more acid soil conditions than can the red. Acid soils favor red-top grass rather than timothy. Sorrel is a weed that thrives in both alkaline and acid soils, and its presence would not be an index if it could stand competition with clover in an alkaline soil. The clover can crowd it out if the ground is not too badly infested with seed, and even then the sorrel must finally give way. Where sorrel and plantain cover the ground that has been seeded to clover and grass, the evidence is strong that the soil conditions are unfriendly to the better plants on account of a lime deficiency. The experienced farmer who notes the inclination of his soil to favor alsike clover, red-top, sorrel, and plantain should infer that lime is lacking. If doubt continues, he should make a test.
The Litmus-paper Test.—A test of fair reliability may be made with litmus paper. A package of blue litmus paper can be bought for a few cents at any drug store. This paper will turn pink when brought into contact with an acid, and will return to a blue if placed in lime-water. A drop of vinegar on a sheet of the paper will bring an immediate change to pink. If the pink sheet be placed in lime-water, the effect of the lime in correcting the acidity will be evidenced by the return in color to blue.
To test the soil, a sample of it may be put into a basin and moistened with rain-water. Several sheets of the blue litmus paper should be buried in the mud, care being used that the hands are clean and dry. When one sheet is removed within a few seconds and rinsed with rain-water, if any pink shows, there is free acid present. Another sheet should be taken out in five minutes. The rapidity with which the color changes, and the intensity of the color, are indicative of the degree of acidity, and aid the judgment in determining how much lime should be used. If a sheet of the paper retains its blue color in the soil for twenty minutes, there probably is no lime deficiency. The test should be made with samples of soil from various parts of the field, and they should be taken beneath the surface. One just criticism of this test is that while no acidity may be shown, the lime content may be too low for safety.
A Practical Test.—The importance of alkalinity in soils is so great, and the prevalence of acidity has such wide-spread influence to-day, limiting the value of the clovers on a majority of our farms, that a simple and more convincing test is suggested here. Every owner of land that is not satisfactorily productive may learn the state of his soil respecting lime requirement at small expense. When a field is being prepared for seeding to the grain crop with which clover will be sown, a plat containing four square rods should be measured off, and preferably this should be away from the border to insure even soil conditions. A bushel of lump-lime, weighing eighty pounds, should be slaked and evenly distributed over the surface of the plat of ground. It can be broadcasted by hand if a spreader is not available, and mixed with the surface soil while in a powdered state. The plat of ground should be left as firm as the remainder of the field, so that all conditions may be even for the test. The appearance of the clover the following year will determine whether lime was needed or not. There is no reason why any one should remain in doubt regarding the lime requirement of his fields. If income is limited by such a cause, the fact should be known as soon as possible.
Duration of Effect.—Soil acidity is not permanently corrected by a lime application. The original supply failed to prove lasting, and the relatively small amount given the land in an application will become exhausted. The duration depends upon the degree of acidity, the nature of the soil and its crops, and the size of the application. Experiments at the Pennsylvania experiment station have shown that an application only in sufficient amount to correct the existing acidity at the time of application will not maintain an alkaline condition in the soil, even for a few months. There must be some excess at hand to unite with acids as formed later in the crop-rotation, or limings must be given at short intervals of time to maintain alkaline conditions.
Experience causes us to assume that enough lime should be applied at one time to meet all requirements for a single crop-rotation of four, five, or six years, and, wherever lime is cheap, the unpleasant character of the labor inclines one to make the application in sufficient amount to last through two such rotations. It is a reasonable assumption, however, that more waste results from the heavier applications at long intervals than from light applications at short intervals. In any event need will return, and soil acidity will again limit income if applications do not continue to be made.
Forms of Lime.—There is unnecessary confusion in the mind of the public regarding the forms of lime that should be used. If amounts greatly in excess of needs were being applied, the form would be a matter of concern. There would arise the question of soil injury that might result from the use of the lime in caustic form. Again, if pulverized limestone were used, a very heavy application would bring up the question of coarseness in order that waste by leaching might be escaped. Most farms needing lime do not have cheap supplies, and the consideration is to secure soil alkalinity at a cost that will not be excessive. Freight rates and the cost of hauling to the fields, added to first cost of the lime, limit applications on most farms to the necessities of a single crop-rotation which includes clover, or, at the most, to two crop-rotations. Under these circumstances it is best to let cost of correction of soil acidity determine the form of lime to be used.
The material that will render the soil friendly to clover for the least money is the right one to select. We need to be concerned only with the relative efficiencies of the various forms of lime, as measured in terms of money. That which will most cheaply restore heavy clover growths to the land is the form of lime to be desired. The contentions of salesmen may well be disregarded as they produce confusion and delay a work that is important to the farmer.
Definitions.—The use of the various forms of lime will become general, and the terms employed to designate them should be understood. They vary in their content of acid-correcting material, and their correct names should be used with accuracy.
Stone-lime, often called lump-lime or unslaked lime, or calcium oxide or CaO, is a form widely known, and may be taken as a standard. It is the ordinary lime of commerce, and is obtained by the burning of limestone. One hundred pounds of pure limestone will produce 56 pounds of stone-lime (CaO).
Pulverized lime, often called ground lime, is stone-lime after being pulverized to permit even distribution. When it is fully exposed to the air or moisture, it slakes and doubles in volume.
Hydrated lime, often called slaked lime, is a combination of stone-lime and water. The water causes an increase in weight of 32 per cent, 56 pounds of stone-lime becoming 74 pounds of the hydrate.
Pulverized limestone, often called carbonate of lime, is the unburned limestone made fine so that good distribution may be possible.
Air-slaked lime, often called carbonate of lime, is stone-lime or hydrated lime combined with carbonic acid from the air, and thereby increased in weight. Fifty-six pounds of stone-lime, or 74 pounds of hydrated lime, become 100 pounds of air-slaked lime.
Agricultural lime, or land-lime, may embrace anything that the manufacturer of lime chooses to market. It may be reasonably pure unslaked lime, or it may have less value than a finely pulverized pure limestone. There is a custom of grinding the core, or partially burned limestone of the kiln, together with impurities removed from builders' lime, and with this may be put some air-slaked lime. Some manufacturers market under this name a lime of excellent value. There is no standard, and one should not pay more than a finely pulverized pure limestone would cost unless he knows that the content of fresh burned lime is high.
The element with which we are concerned in any of these forms of lime is calcium. It is the base whose union with the acids destroys the latter. It should be obvious that the addition of water to stone-lime, which adds weight and causes 56 pounds of the stone-lime to become 74 pounds of hydrated lime, adds no calcium. Likewise the change to the air-slaked condition adds no calcium, but again adds weight.
The Kind to Apply.—If a soil contains free acid, the amount of calcium needed is definite. The form of lime that can supply the need in that particular field at least expenditure of money and trouble is the one to be selected. A ton of stone-lime, or pulverized lime, can correct as much acid as 2640 pounds of hydrated lime or 3570 pounds of pulverized limestone, if all the original material was pure.
In other words, if the value of a given weight of pulverized limestone is placed at 100, the value of the same weight of hydrated lime would be 132 and the value of stone-lime would be 180, when each was finely divided and distributed throughout the surface soil.
The Fineness of Limestone.—Experiments at the Pennsylvania experiment station have shown that limestone has practically immediate availability in an acid soil if all of it has ability to pass through a screen having 60 meshes to the linear inch. Much of the limestone meeting this test doubtless is fine enough to pass through an 100-mesh screen. The requirement that a 60-mesh screen be used in testing is a satisfactory one to the buyer that wants immediate results in the field. A coarser product must be used in larger amount per acre, as only the fine particles are available at once, and the object of the application is to correct all the acidity. Where a coarse product, containing some fine particles, can be used at such a low price per ton that the application may consist of a large number of tons per acre, the practice may be commended, but the essential thing is immediate results, and only finely divided limestone can give them. Any long railway or wagon haul makes a heavy application of coarsely pulverized limestone inexpedient.
Hydrated Lime.—Many salesmen are too enthusiastic in their claims for hydrated lime. It has advantages over pulverized limestone, stone-lime, and pulverized lime, and there are disadvantages. The buyer of pulverized limestone pays for the haul on 100 pounds of material to get the 56 pounds of lime carried, while 74 pounds of the hydrate furnish the same amount of actual lime, if all of it is a hydrate. While the hydrate contains less strength than the stone-lime, it is in good physical condition for distribution, and the stone-lime must be slaked. The buyer will bear in mind, moreover, that much of the stone-lime which is burned on farms comes from limestone that is not very pure, and all impurity is waste. Most manufacturers of the hydrate locate their costly plants where the limestone is relatively pure. Prudent business reasons dictate such a course. A careful manufacturer of hydrated lime takes out imperfectly burned and other faulty material with screens. These advantages have some weight, but the fact remains that a ton of pure stone-lime has considerably more acid-correcting power than a ton of the hydrate.
Stone-lime.—Stone or lump-lime is composed of the 56 per cent of a pure limestone that gives value to the limestone. Forty-four pounds of waste material were driven off in the burning. Where railway or wagon hauls are costly, the purchase of stone-lime is indicated. There is advantage in getting this lime in pulverized form, provided it can be distributed in the soil before moisture from the air induces slaking and consequent bursting of the packages. The necessity of rapid handling has limited the popularity of pulverized unslaked lime, but no other form is equal to it when it is wholly unslaked. Some manufacturers grind the partially burned limestone often found in kilns, and furnish goods little better than pulverized limestone.
The slaking of stone-lime should be done in a large pile, and the distribution may be made with lime-spreaders. When the application is fairly heavy, a manure-spreader does satisfactory work. A good lime-spreader is to be desired, but care must be used to remove any stones or similar impurities in the slaked lime when filling it. Such spreaders are on the market.
The practice of slaking lime in small piles in the field is wasteful. It is difficult to reduce all the lime to a fine powder and to make even distribution over the surface. Any excess of water from rains puddles some of the lime, destroying practically all its immediate effectiveness. Distribution with shovels is necessarily imperfect.
The labor of slaking stone-lime and the difficulty in distribution are two factors to be considered when selecting the form of lime to be used. They may counter-balance in some instances the higher percentage of actual lime when comparison is made with the hydrate. That is a question to be decided by the buyer. He must be willing to use methods that will secure even distribution. The prevailing practice, however, of marketing the hydrate at a much higher price per ton than the stone-lime should prevent sales to farmers. The price paid for ease of handling is too great when purchase of the hydrate is made under such circumstances. It is better to do the slaking at home, furnishing the added weight of 32 per cent in water on the farm.
Ashes.—Hard-wood ashes have ceased to have much importance as a source of lime for land, but their use is held in high esteem even by those who regard fertilizers as mere stimulants and doubt the efficiency of lime. Hard-wood ashes, unleached, clean and dry, are valuable for acid soils. Their content of potash, which is variable and averages about 4 per cent, formerly was given all the credit for the soil improvement and increased clover growth that resulted from their use. Tests with other carriers of potash have shown that the potash probably produced only a small part of the effect noted, and the benefit is attributable to the lime in the ashes which exists in an effective form. The content of lime is variable, and largely so on account of the percentage of moisture and dirt that may be found in most ashes, and when no analysis has been made, the estimate of value should not be based on more than 30 to 40 per cent of carbonate of lime. The price of ashes runs so high, as a result of prejudice in favor of this well-known kind of soil amendment, that it rarely is advisable to buy them. Pure lime is a cheaper means of correcting the soil acidity, and the sulphate or the muriate of potash is by far the cheaper source of potash.
Marl.—Marls vary widely in composition. When quite pure, they contain 90 or more per cent of carbonate of lime, and have a value per ton about equal to finely pulverized limestone, and near half the value per ton of stone-lime. There are marls that are carriers of potash and phosphoric acid, and are to be valued accordingly as fertilizers.
Magnesian Lime.—Some limestone is a nearly pure calcium compound, and yields a pure lime, while much limestone contains a high percentage of magnesia. The latter is preferred by manufacturers who furnish pulverized lime because it does not slake readily, and is less liable to burst the packages before required for use. A pound of magnesian lime will correct a little more acid than a pound of pure lime, and no preference may be shown the latter on that score. There are soils in which the proportion of magnesia to pure lime is too great for best results with some plants, as plant biologists assure us, but there is too little definite information respecting these soils to justify one in paying more for a high calcium lime than for a magnesian lime when it is to be used on acid land. The day may come when more will be known, but the rational selection to-day is the material that will do the required work in the soil for the least money.
Amount per Acre.—The amount of lime that should be applied to an acre of land depends upon the degree of its acidity, the nature of the soil, the cheapness of the lime, and the character of the crops to be grown. The actual requirement for the moment could be determined by a chemical test, but the application should carry to the soil an amount in excess of immediate requirement. When clover has ceased to grow within recent years, it is a fair inference that the deficiency, if it exists, has not become great. When sorrel and plantain have gained a strong foothold, indicating that good grasses are unable to replace clover, the degree of acidity probably is higher. The results of tests at experiment stations and on farms show that 1000 pounds of pulverized lime, or one ton of pulverized limestone, evenly distributed throughout the surface soil, can restore clover to the crop-rotation on much land. This is an application so light that a state of alkalinity cannot be long retained. It is better to apply the equivalent of a ton of stone-lime in the case of all heavy soils that have shown any acidity. Where lime is low in price, 3000 pounds of stone-lime, or its equivalent in any other form of lime, is advised, the belief being that such an application will maintain good soil conditions through two crop-rotations, or eight to ten years. This amount can be applied quite successfully with a manure-spreader, and meets the convenience of the man who burns his own lime and does not want to screen it for use in a lime-spreader. The man who must buy his lime, and pay a freight charge upon it, will find it better to use only a ton per acre. This advice applies to heavy soils. A light, sandy soil should be given only a small application, as otherwise physical condition may be injured. The lime, used in excess, has an undue binding effect upon the sand. An application of 1000 pounds of stone-lime per acre can be made with safety.
Time of Application.—The use of lime on land should be associated in the land-owner's thoughts with the growing of clover. It does help soil conditions so that more grain can be produced, but if it is permitted to displace the use of fertilizers, and does not lead to the growth of organic matter, harm will result in the end. Lime should be applied to secure clover, and therefore it should be mixed with the soil before the clover is sown. The application may be made when fitting the seed-bed for the grain with which clover usually is seeded, or may be given a year or two years previous to that time. The important point is to have the soil friendly to plant life when a sod is to be made.
Lime should be put on ground always after the plowing, and it should be well mixed with the surface soil. Even distribution is just as important in its case as in that of fertilizers. A good practice is to break a sod for corn, harrowing and rolling once, and then to put on the lime. A cut-away or disk harrow should be used to mix the lime with the soil before any moisture causes it to cake. When large crumbs form, immediate efficiency is lost.
If the application is light, and may barely be equal to immediate demand, it is better practice to put on the lime when preparing the seed-bed for the wheat or other small grain in which the clover will be sown. It should never be mixed with the fertilizer nor applied with the seed. The lime should go into the soil a few days, or more, prior to the seeding. The soil having been put into a condition favorable to plant life, the seeding and the use of commercial fertilizers should proceed as usual.
Lime should never be mixed with manure in the open air, but it is good practice to plow manure down, and then to use lime as indicated above, if needed. If manure and lime must be used after the land has been plowed, the lime should be disked well into the soil before the manure is applied, and it is advisable that the interval between the two applications be made as long as possible.
Office of Organic Matter.—The restoration of an impoverished soil to a productive state usually is a simple matter so far as method is concerned. It may be a difficult problem for the individual owner on account of expense or time involved, but he has only a few factors in his problem. Assuming that there is good drainage, and that the lime requirement has been met, the most important consideration is organic matter. A profitable agriculture is dependent upon a high percentage of humus in the soil. Average yields of crops are low in this country chiefly because the humus-content has been greatly reduced by bad farming methods.
Nature uses organic matter in the following ways:
1. To give good physical condition to the soil. The practical farmer appreciates the importance of this quality in a soil. Clayey soils are composed of fine particles that adhere to each other. They are compact, excluding air and failing to absorb the water that should be held in them. The excess of water finally is lost by evaporation, and the sticky mass becomes dry and hard. The incorporation of organic matter with clay or silt changes the character of such land, breaking up the mass, and giving it the porous condition so essential to productiveness. Improved physical condition is likewise given to a sandy soil, the humus binding the particles together.
2. To make the soil retentive of moisture. Yields of crops are limited more by lack of a constant and adequate supply of moisture throughout the growing season than by any other one factor. Decayed organic matter has great capacity for holding moisture, and in some measure should supply the water needed during periods of light rainfall.
3. To serve, directly and indirectly, as a solvent of the inert plant-food in the soil that is known as the "natural strength" of the land. Its acids do this work directly, and by its presence it makes possible the work of the friendly bacteria that are man's chief allies in maintaining soil fertility.
4. To furnish plant-food directly to growing plants. Even when it has been produced from the soil supplies alone, there is great gain because the growing crop must have immediately available supplies. Many of the plants used in providing humus for the soil are better foragers for fertility than other plants that follow, sending their roots deeper into the subsoil or using more inert forms of fertility.
The Legumes.—Any plant that grows and rots in the soil adds to the productive power of the land if lime is present, but plants differ in value as makers of humus. There are only ten essential constituents of plant-food, and the soil contains only four that concern us because the others are always present in abundance. If lime has been applied to give to the soil a condition friendly to plant life, we are concerned with three constituents only, viz. nitrogen, phosphoric acid, and potash. The last two are minerals and cannot come from the air. They must be drawn from original stores in the soil or be obtained from outside sources in the form of fertilizers. The nitrogen is in the air in abundance, but plants cannot draw directly from this store in any appreciable amount. The soil supply is usually light because nitrogen is unstable in character and has escaped from all agricultural land in vast amounts during past ages.
Profitable farming is based upon the great fact that we have one class of plants which can use bacteria to work over the nitrogen of the air into a form available for their use, and the store of nitrogen thus gained can be added to the soil's supply for future crops. These plants, known as legumes, embrace the clovers, alfalfa, the vetches, peas, beans, and many others of less value. They provide not only the organic matter so much needed by all thin soils, but at the same time they are the means of adding to the soil large amounts of the one element of plant-food that is most costly, most unstable, and most deficient in poor soils. Their ability to secure nitrogen for their own growth in poor land also is a prime consideration in their selection for soil improvement, assuring a supply of organic matter where otherwise partial failure would occur.
Storing Nitrogen.—Man needs protection from his own greed, and nature's checks are his salvation. An illustration is afforded in the case of legumes grown for the maintenance of soil fertility. The clovers and some other legumes are seeded primarily for the benefit of the soil. The need of organic matter is recognized, and a cheap supply of nitrogen is wanted for other crops in the rotation. The purpose of the seeding is praiseworthy, but if all of the product were available for use off the land, observation teaches that the soil producing the crop probably would fare badly. The crops grown prior to the season devoted to legumes proclaim their need of better soil conditions, more organic matter, and more nitrogen, but the legumes, appropriating nitrogen for themselves, give to the land a more prosperous appearance, and the disposition to harvest everything that is in sight prevails.
There is the excusing intention to return to the soil the residue from feeding, which should be nearly as valuable as the original material, while the fact usually is that faulty handling of the manure results in heavy loss, and the distribution of the remainder is imperfect. There is no happier provision of nature for the guarding of the soil's interests than the unavailability for man's direct use of a considerable part of most plants, thus saving to the land a portion of its share of its products. The humus obtained from plant-roots, stubble, and fallen leaves forms a large percentage of all the humus obtained by land whose fertility is not well guarded by owners. This proportion is large in some legumes, amounting to 30 or 40 per cent in the case of red and mammoth clover.
The Right Bacteria.—The word "bacteria" has had a grudging admission to the vocabulary of practical farmers, and the reason is easily stated. The knowledge of bacteria and their work is recent and limited. They are many in kind, and scientists are only in the midst of their discoveries. The practical farmer does well to let bacteriologists monopolize interest in the whole subject except in so far as he can provide some conditions that have been demonstrated to be profitable. The work of bacteria must come more and more into consideration by the farmer because nature uses them to produce a vast amount of the change that is going on around us.
In consideration of the value of legumes we must take into account the bacteria which they have associated with them, and through which they obtain the atmospheric nitrogen. This would be a negligible matter, it may be, if all legumes made use of the same kind of bacteria. It is true that the bacteria must have favorable soil conditions, but they are the same favorable conditions that our plants require. A fact of importance to the farmer is that the bacteria which thrive on the roots of some legumes will not serve other legumes. This is a reason for many failures of alfalfa, crimson clover, the soybean, the cowpea, hairy vetch, and other legumes new to the region.
Soil Inoculation.—The belief that the right kind of bacteria may be absent from the soil when a new legume is seeded, and that they should be supplied directly to the soil, has failed in ready acceptance because examples of success without such inoculation are not uncommon. Even if the explanation of such success is not easy, the fact remains that legumes new to a region usually fail to find and develop a supply of bacteria adequate for a full yield, and some of these legumes, of which alfalfa is an example, make a nearly total failure when seeded for the first time without soil inoculation. Experiment stations and thousands of practical farmers have learned by field tests that the difference between success and failure under otherwise similar conditions often has been due to the introduction of the right bacteria into the soil before the seeding was made.
Explanations offered for any phenomenon may later become embarrassing in the light of new knowledge. We do not really need to know why an occasional soil is supplied with the bacteria of a legume new to it. We have learned that the bacteria of sweet clover serve alfalfa, and this accounts for the inoculation of some regions in the east. We believe that some bacteria are carried in the dust on the seed, and produce partial inoculation. Other causes are more obscure. The cowpea trails on the ground, and carries its bacteria more successfully than the soybean. Most legumes require a soil artificially inoculated when brought into a new region, failing otherwise in some degree to make full growth.
Method of Inoculation.—The bacteria can be transferred to a new field by spreading soil taken from a field that has been growing the legume successfully. The surface soil is removed to a depth of three inches, and the next layer of soil is taken, as it contains the highest percentage of bacteria. They develop in the nodules found on the feeding roots of the plants. The soil is pulverized and applied at the rate of 200 pounds per acre broadcast. If the inoculated soil is near at hand and inexpensive, 500 pounds should be used in order that the chance of quick inoculation may be increased. The soil should be spread when the sun's rays are not hot, and covered at once with a harrow, as drying injures vitality. The soil may be broadcasted by hand or applied with a fertilizer distributer. The work may be done at any time while preparing the seed-bed. The bacteria will quickly begin to develop on the roots of the young plants, and nodules may be seen in some instances before the plants are four weeks old.
Pure cultures may be used for inoculation. Some commercial concerns made failures and brought the use of pure cultures into disrepute a few years ago, but methods now are more nearly perfect, and it is possible to buy the cultures of all the legumes and to use them with success.
Prices continue too high to make the pure cultures attractive to those who can obtain inoculated soil with ease. If land has been producing vigorous plants, and if it contains no weeds or disease new to the land to be seeded, its soil offers the most desirable means of transferring the bacteria.
The claim is made by some producers of pure cultures that their bacteria are selected for virility, and should be used to displace those found in the farmer's fields. The chances are that, if soil conditions are good, the bacteria present in the soil are virile, and if the conditions are bad, the pure cultures will not thrive. All eastern land is supplied with red clover bacteria, just as some western land possesses alfalfa bacteria, and partial clover failure has causes wholly apart from the character of its bacteria.
We do not have definite knowledge concerning duration of inoculation nor the manner in which it is maintained when legumes are not growing, but we do know that when a legume has once made vigorous growth in a field, the soil will remain inoculated for a long term of years.
Red Clover.—Wherever red clover thrives there is no more valuable plant than this legume for making and keeping soils productive under ordinary crop-rotations. The tyro in farming finds his neighbors conservative in thought and method, and may rightly see room for improvement. He naturally turns to new crops that are receiving much exploitation, but should bear in mind that the world nowhere has found a superior to red clover as a combined fertilizing and forage crop for use in short rotations. Farmers turn aside from it because it turns aside from them. There has been increasing clover failure in our older states for a long term of years. It has become the rule to seed to timothy with the clover in the short crop-rotations as well as in the longer ones, and chiefly for the reason that clover seeding has become no longer dependable. In many regions the proportion of timothy seed used per acre has been made large because the clover would not surely grow. In the winter-wheat belt, where the custom has been to make such seedings with wheat, timothy being sown in the fall and clover the next spring, this increase in the timothy has made matters worse for the clover, but it has helped to insure a sod and a hay crop. "Clover sickness," supposedly resulting from close clover rotations, and the prevalence of plantain and other weeds, have been assigned as a partial cause of clover failure. It is only within recent years that the true cause of much failure has been recognized.
Clover and Acid Soils.—There are limited areas in which some clover disease has flourished, and in some years insect attacks are serious. Barring these factors which have relatively small importance when the entire clover area is taken into account, the causes of clover failure are under the farmer's control. The need of drainage increases, and the deficiency in organic matter becomes more marked. The sale of hay and straw, and especially the loss of liquid manures in stables, have robbed many farms. These are adverse influences upon clover seedings, but the most important handicap to clover is soil acidity. There is sad waste when high-priced clover seed is put into land so sour that clover bacteria cannot thrive, and there is ten-fold more waste in letting land fail to obtain the organic matter and nitrogen clover should supply. When land-owners refuse to let their soils remain deficient in lime, clover will come into a prominence in our agriculture that it never previously has known.
Methods of Seeding.—It is a common practice to sow clover in the spring, either with spring grain or with wheat or rye previously seeded in the fall. This method has much to commend it. The cost of making the seed-bed is transferred to the grain crop, and there is little outlay other than the cost of seed. Wheat and rye offer better chances to the young clover plants than do the oat crop which shades the soil densely and ripens later in the summer. The amount of seed that should be used depends upon the soil, the length of time the sod will stand, and the purpose in growing the clover. When soil fertility is the one consideration, 12 to 15 pounds of bright, plump medium red clover seed per acre should be sown. A fuller discussion of the principles involved in making a sod and of seed mixtures is given in Chapters VII and VIII.
Fertility Value.—Attempts have been made to express the actual value of a good clover crop to the soil in terms of money. The number of pounds of matter in the roots and stubble has been determined, and analyses show the percentage of nitrogen, phosphoric acid, and potash contained. The two crops harvested in the second year of its growth likewise have their content of plant-food determined. If the total amounts of nitrogen, phosphoric acid, and potash have their values fixed by multiplying the number of pounds of each ingredient of plant-food by their respective market values, as is the practice in the case of commercial fertilizers, a total valuation may be placed upon the clover, roots and top, as a fertilizer. Such valuation is so misleading that it affords no true guidance to the farmer. In the first place, the phosphoric acid and potash were taken out of the soil, and while some part of these materials may have been without immediate value to another crop until used by the clover, no one knows how much value was given to them by the action of the clover. Again, no one knows what percentage of the nitrogen in the clover came from the air, and how much was drawn from the soil's stores. The proportion varies with the fertility of the land, the percentage of nitrogen taken from the air being greater in the case of badly depleted soils.
A big factor of error is found in the valuations of the ingredients found in the crop. All plant-food is worth to the farmer only what he can get out of it. He may be able to use 50 pounds of nitrogen per acre in the form of nitrate of soda, at 18 cents a pound, when growing a certain crop, but could not afford to buy, at market price of organic nitrogen, all the nitrogen found in the clover crop, and therefore it does not have that value to him.
On the other hand, these estimates do not embrace the great benefit to the physical condition of the soil that results from the incorporation of a large amount of vegetable matter.
Discussion has been given to this phase of the question in the interest of accuracy. Values are only relative. The practical farmer can determine the estimate he should put upon clover only by noting its effect upon yields in the crop-rotation upon his own farm. It is our best means of getting nitrogen from the air, it provides a large amount of organic matter, it feeds in subsoil as well as in top soil, bringing up fertility and filling all the soil with roots that affect physical condition favorably, and it provides a feed for livestock that gives a rich manure.
Taking the Crops off the Land.—The feeding value of clover hay is so great that the livestock farmer cannot afford to leave a crop of clover on the ground as a fertilizer. The second crop of red clover produces the seed, and, if the yield is good, is very profitable at the prices for seed prevailing within recent years. The amount of plant-food taken off in the hay and seed crops would have relatively small importance if manure and haulm were returned without unnecessary waste. Van Slyke states that about one third of the entire plant-food value is contained in the roots, while 35 to 40 per cent of the nitrogen is found in the roots and stubble. Hall instances one experiment at Rothamstead in which the removal of 151 pounds of nitrogen in the clover hay in one year left the soil enough richer than land by its side to produce 50 per cent more grain the next year. He cites another experiment in which the removal of three tons of clover hay left the soil so well supplied with nitrogen that its crop of Swede turnips two years later was over one third better than that of land which had not grown clover, the application of phosphoric acid and potash being the same. When two tons of well-cured clover hay are harvested in June, removing about 80 pounds of nitrogen, 45 to 50 pounds are left for the soil. The amounts of potash are about the same, while phosphoric acid is much less in amount.
Physical Benefit of the Roots.—While the roots and stubble contain less than two fifths of the total plant-food in a clover crop, one may not safely infer that the removal of the crop for hay reduces the beneficial effect of the clover to the soil fully 60 per cent, or more. The roots break up the soil in a way not possible to a mass of tops plowed down. They improve the physical condition of the subsoil as well as the top soil. The amount of the benefit depends in part upon the nature of the land. Its value cannot be surely determined, but the facts are called to mind as an aid to judgment in deciding upon the method of handling the clover crop.
Used as a Green Manure.—Where dependence must be placed upon clover as a fertilizer, little or no manure being returned to the land, at least one of the two clover crops within the year should be left on the land. The maximum benefit from clover, when left on the land, can be obtained by clipping it before it is sufficiently heavy to smother the plants, leaving it as a mulch. When the cutter-bar of the mower is tilted upward, the danger of smothering is reduced. Truckers, remote from supplies of manure, have found it profitable to make two such clippings just prior to blossoming stage, securing a third heavy growth. The amount of humus thus obtained is large, and the benefit of the mulch is an important item.
Some growers clip the first crop for a mulch, and later secure a seed crop. The early clipping and the mulch cause increase in yield of seed.
A common practice is to take one crop off for hay, and to leave the second for plowing down the following spring. Early harvesting of the clover for hay favors the second crop.
When to turn Down.—When the maximum benefit is desired for the soil from a crop of clover, the first growth should not be plowed down. Its office should be that of a mulch. In its decay all the mineral plant-food and most of the nitrogen go into the soil. The second crop should come to maturity, or near it. As a rule, there is gain, and not loss, by letting the second crop lie on the ground until spring if a spring-planted crop is to follow. Some fall growth, and the protection from leaching, should equal any advantage arising from rotting the bulky growth in the soil. In some regions it is not good practice to plow down a heavy green crop on account of the excessive amount of acid produced. When this has been done, the only corrective is a liberal application of lime.
Mammoth Clover.—When clover is grown with timothy for hay, some farmers prefer to use mammoth clover in place of the medium red. It may be known as sapling clover, and is accounted a perennial, though it is little more so than the red. It is a strong grower and makes a coarse stalk but, when grown with timothy, it has the advantage over the red in that the period of ripening is more nearly that of the timothy. It inclines to lodge badly, and should be seeded thinly with timothy when wanted for hay. The roots run deep into the soil, and this variety of clover compares favorably with the medium red in point of fertilizing power, the total root-growth being heavier. While its yield of hay, when seeded alone, is greater than the first crop of the red, its inclination to lodge and its coarseness are offsets. It produces its seed in the first crop, and the after-growth is small, while red clover may make a heavy second crop. Its use should become more general on thin soils, its strong root-growth enabling it to thrive better than the red, and the lack of fertility preventing the stalks from becoming unduly coarse for hay. The amount of seed used per acre, when grown by itself, should be the same as that of red clover.
Alsike Clover.—A variety of clover that may have gained more popularity than its merit warrants is alsike clover. It is more nearly perennial than the mammoth. The roots do not go deep into the subsoil like those of the red or the mammoth, and therefore it is better adapted to wet land. It remains several years in the ground when grazed, and is usually found in seed mixtures for pastures. It is decumbent, and difficult to harvest for hay when seeded alone. It is credited with higher yields than the red by most authorities, but this is not in accord with observation in some regions, and it is markedly inferior to the red in the organic matter and the nitrogen supplied the soil in the roots.
The popularity of this clover is due to its ability to withstand some soil acidity and bad physical conditions. In regions where red clover is declining on account of lack of lime, one may see some alsike. The rule is to mix alsike with the red at the rate of one or two bushels of the former to six bushels of the latter. As the seed of the alsike is hardly half as large as that of the red, the proportion in the mixture is greater than some farmers realize. The practice is an excellent one where the red will not grow, and the alsike adds fertility, but when the soil has been made alkaline, the red clover should have nearly all the room. Alsike is a heavy producer of seed.
Crimson Clover.—Wherever crimson clover is sufficiently hardy to withstand the winter, as in Delaware and New Jersey, it is a valuable aid in maintaining and increasing soil fertility. It is a winter annual, like winter wheat, and should be seeded in the latter half of summer, according to latitude. It comes into bloom in late spring. The plant has a tap-root of good length, but in total weight of roots is much inferior to the red. This clover, however, compares favorably with red clover in the total amount of nitrogen added to the soil by the entire plant when grown under favorable conditions. It is peculiarly fitted for a cover crop in orchards and wherever spring crops are removed as early as August, or a seeding can be made in them, as is the case with corn. Even when winter kills the plants, a successful fall growth is highly profitable, adding more nitrogen before winter than red clover seeded at the same time. Where the plants do not winter-kill, they are plowed down for green manure when in bloom in May, or earlier in the spring to save soil moisture and permit early planting, although a good hay for livestock can be made, and the yield is about the same as that of the first crop of red clover.
In the northern states a large amount of money has been wasted in experimental seedings with crimson clover, and it is only in exceptional cases that it continues to be grown. There is reason to believe that many of these failures were due to lack of soil inoculation. The Pennsylvania experiment station is located in a mountain valley where winters are severe. Crimson clover is under test with other cover crops for an experimental orchard, and success with it has increased as the soil has become fully inoculated. This view is supported by the experience of various growers in the North, and while crimson clover can never make the success in a cold climate that it does in Delaware, there is a much wider field of usefulness for it than is now occupied. Experiments should be made with it under favorable conditions respecting moisture and soil tilth. Fifteen pounds of seed should be used, and the seed should be well covered, as is the case with all seeds sown in mid-summer.
Adaptation to Eastern Needs.—The introduction of alfalfa into the eastern half of the United States will prove a boon to its depleted soils, encouraging the feeding of livestock and adding to the value of manures. It will affect soils directly, as does red clover, when farmers appreciate the fact that its rightful place on their farms is in rotation with grain. Under western conditions, where no other crop can compete with it in value, as is the case in semi-arid belts, its ability to produce crops for a long term of years adds much to its value, but in eastern agriculture this characteristic is not needed. On most soils of the east it will not remain productive for more than four to six years, and that fact detracts little from its value. It should fit into crop-rotations, adding fertility for grain crops. When grown in a six-years rotation with corn and oats or other small grain, it furnishes a rich sod for the corn, and the manure made from the hay helps to solve the farmer's fertility problem.
Fertility and Feeding Value.—Vivian says that "the problem of the profitable maintenance of fertility is largely a question of an economic method of supplying plants with nitrogen." The greatest value of alfalfa to eastern farming lies in its ability to convert atmospheric nitrogen into organic nitrogen. It has no equal in this respect for relatively long crop-rotations, storing in its roots and successive growths of top far more nitrogen within three or four years than is possible to any other of our legumes. A good stand of alfalfa, producing nine crops of hay in the three years following the season of seeding, will produce from nine to twelve tons of hay. Good fields, under the best conditions, have produced far more, but the amounts named are within reach of most growers on land adapted to the plant. A ton of hay, on the average, contains as much nitrogen as five or six tons of fresh stable manure. Thus there comes to the farm a great amount of plant-food, to be given the land in the manure, and in addition the roots and stubble have stored in the ground enough nitrogen to feed a successive corn crop, and a small grain crop which may follow the corn. Moreover, the roots have filled the soil with organic matter, improving the physical condition of the soil and subsoil.
Another gain is found in the content of phosphoric acid and potash in the manure, much of which was drawn from soil supplies out of reach of the other farm crops. The profit from introduction of alfalfa into a region's agriculture is very great.
Alfalfa makes a nutritious and palatable feed for livestock. A ton contains as much digestible protein as 1600 pounds of wheat bran.
Climate and Soil.—The experimentation with alfalfa by farmers has been wide-spread, and the percentage of failure has been so large that many have believed this legume was unfitted to the climate and soil of the country east of the Missouri River. Successful experience has shown that it can be made to take a considerable place in eastern crop-schemes. The climate is not unfavorable, as is evidenced by large areas of good alfalfa sods on thousands of farms. The abundant rainfall brings various weeds and grasses into competition with it, and that will remain a serious drawback until growers learn to clean their surface soils by good tillage before seeding.
Any land that is sufficiently well drained to produce a good corn crop in a wet summer can grow alfalfa if the seed-bed is rightly made. The loose soils are more difficult to seed successfully than is the land having enough clay to give itself body, although most experimenters select their most porous soils. All farms having good tilth can bring alfalfa into their crop-rotations.
Free Use of Lime.—The conditions requisite to success in alfalfa-growing are not numerous, but none can be neglected. Alfalfa should be given a calcareous soil when possible, but an acid soil can be made favorable to alfalfa by the free use of lime. There must remain a liberal amount after the soil deficiency has been met, and when the use of lime is on a liberal scale, the pulverized limestone makes the safest carrier. However, 50 bushels of stone-lime per acre can be used safely on any land that is not distinctly sandy, and that amount is adequate in most instances.
Inoculation.—The necessity of inoculation has been discussed in Chapter IV. Eastern land would become inoculated for alfalfa if farmers would adopt the practice of mixing a little alfalfa with red clover whenever making seedings. Some alfalfa plants usually make growth, securing the bacteria in the dust of the seed, presumably. The addition of one pound of alfalfa seed per acre would assist materially in securing a good stand when the day came that an alfalfa seeding was desired.
Fertilization.—The ability of alfalfa to add fertility to the farm, and directly to the field producing it when all the crops are removed as hay, does not preclude the necessity of having the soil fertile when the seeding is made. The plants find competition with grass and other weeds keen under eastern skies where moisture favors plant-life. In their first season this is markedly true. There should be plenty of available plant-food for the young plants. Stable manure that is free from the seeds of pernicious weeds makes an excellent dressing. It is good practice to plow down a heavy coat of manure for corn and then to replow the land for alfalfa the next season. A top-dressing of manure is good, affording excellent physical condition of the surface for starting the plants. Eight tons per acre make a good dressing.
If land is not naturally fertile, mineral fertilizers should be applied. A mixture of 350 pounds of 14 per cent acid phosphate and 50 pounds of muriate of potash is excellent for an acre of manured land. In the absence of manure, 100 pounds of nitrate of soda and 50 pounds of muriate of potash should be added to the mixture. If the materials are wet, a drier must be used. The fertilizer should be drilled into the ground prior to the seeding.
A Clean Seed-bed.—Much failure with alfalfa is due to summer grasses and other weeds. The moisture in our eastern states favors plant-life, and most soils are thoroughly stocked with the seeds of a large number of weeds. The value of blue-grass and timothy would be comparatively small if they were not capable of monopolizing the ground when well started and given fertility. Alfalfa plants are less capable of crowding out other plants, and especially in their first season. Their habit of growth is unlike that of grass. Rational treatment of alfalfa demands that the surface soil be made fairly clean of weed seed, and this applies with peculiar force to annual grasses, like fox-tail. If attention were paid to this point, failures would be far less numerous.
Old grass land should not be seeded until a cultivated crop has followed the plowing. The land should be in good tilth, and capable of producing a good crop of any sort. Alfalfa is not a plant for poor land, although it does add organic matter and nitrogen.
Varieties.—There is only one variety of alfalfa in common use in this country, and the western-grown seed sold upon the market is known simply as alfalfa. Bound up in this one so-called variety are many strains differing in habit of growth, and their differentiation will occur, just as it has in the case of wheat, and is now proceeding slowly with timothy. The eastern grower at present should use the variety of the west that is furnishing nearly all the seed produced in this country. There is a variety known as Sand Lucerne that has shown value for the light, sandy soils of Michigan. The Turkestan variety was introduced for dry, cold regions, but does not produce much seed.
Clean Seed.—Care should be exercised to secure seed free from impurities. If one is not a competent judge, he should send a sample to his state experiment station for examination. The practice of adulteration is decreasing, but the seed may have been taken from land infested with pernicious weeds.
The impurity most to be feared is dodder. There are several varieties, the seeds varying in size and color. The same pest may be found in clover fields, but the injury is less because the clover stands only two years. The dodder seed germinates in the soil, and the plant attaches itself to the alfalfa, losing its connection with the soil and forming a mass of very fine vines that reach out to other alfalfa plants. In this way it spreads, feeding on the sap of the host plants and killing them.
When the infestation is in only a few spots in the field, the remedy is to cover with straw, soak with kerosene oil, and burn. All the infestation at the edges of these spots must be destroyed.
When the dodder is too widely distributed throughout the field to permit of this treatment, the only course is to plow the field at once, and to grow cultivated crops for two or three years. It is believed that no variety of dodder produces seed freely in the eastern states, and that the hay made from the first crop of alfalfa or red clover will not contain any seed of this pernicious plant.
The Seeding.—When alfalfa has become established on eastern farms, the difficulties in making new seedings will be smaller. The experience of growers will save from mistakes in selection of soils and preparation of the ground, and the thorough inoculation with the right bacteria that can come only with time will do much to insure success. The unwisdom of making seedings in ground filled with grass and other weed seeds will be appreciated. It is quite probable that much successful seeding will be made in wheat and oats, where the alfalfa is to stand only one or two years. These practices are not for the beginner. His land is not thoroughly supplied with bacteria, and every chance should be given the alfalfa.
If there are no annual grasses, such as appear so freely in some regions in mid-summer, spring seeding is excellent. A cover crop is then desirable, and nothing is better for this purpose than barley at the rate of 4 pecks of seed per acre. In all experimental work 25 pounds of bright, plump alfalfa seed per acre should be sown. The seeding should be made as soon as spring comes, the barley being drilled in, and the seed-spouts of the drill thrown forward so that the alfalfa will fall ahead of the hoes and be covered by them.
Seeding in August.—Much land is infested with annual grasses and other weeds, and in such case seedings should be made in August, as described in Chapter VIII.
Subsequent Treatment.—If the alfalfa plants find the bacteria at hand, they will begin to profit from them within the first month of their lives. A large percentage of the plants may fail to obtain this aid in land which has not previously grown alfalfa, and within a few months they indicate the failure by their light color, while the plants liberally supplied with nitrogen through bacteria become dark green. Where there are no bacteria, the plants turn yellow and die.
There are diseases that attack alfalfa, causing the leaves to turn yellow, and when they appear, the only known treatment of value is to clip the plants with a mower without delay. The next growth may not show any mark of the diseases.
When alfalfa is seeded in the spring on rich land, a hay crop may be taken off the same season. If the plants do not make a strong growth, they should be clipped, and the tops should be left as a mulch. The clipping and all future harvestings are made when the stalks start buds from their sides near the ground. This ordinarily occurs about the time some flowers show, and is the warning that the old top should be cut off, no matter how small and unprofitable for harvesting it may be. The exception to this rule is found only in the fall. An August seeding may make such growth in a warm and late autumn that flowering will occur, and lateral buds start, but the growth should not be clipped unless there remains time to secure a new growth large enough to afford winter protection. This is likewise true of a late growth in an old alfalfa field.
Owners of soils that are not well adapted to the alfalfa plant will find top-dressing with manure helpful to alfalfa fields when made in the fall. The severity of winters in a moist climate is responsible for some failures. If the soil is not porous, heaving will occur. A dressing of manure, given late in the fall, and preferably during the first hard freeze, will prevent alternate thawings and freezings in some degree. The manure should have been made from feed containing no seeds of annual grasses or other weed pests.
Rolling in the spring does not serve to settle heaved alfalfa plants. The tap-roots are long, and when they have been lifted by action of frost, they cannot be driven back into place.
It is believed that the permanence of an alfalfa seeding may be increased by the use of mineral fertilizers in the early spring. In the case of one alfalfa field of fifteen years' standing in the east, the fertilizers were applied immediately after the first hay crop of the year was removed. Three hundred and fifty pounds of acid phosphate and 50 pounds of muriate of potash per acre is the mixture recommended. When old alfalfa plants do not stand thickly enough on the ground, grasses and other weeds come in readily. They can be kept under partial control by use of a spring-tooth harrow, the points being made narrow so that no ridging will occur. The harrow should be used immediately after the harvest, and will not injure the alfalfa.
It does not pay to use alfalfa for pasturage in our eastern states because the practice shortens the life of the seeding.
Alfalfa makes a seed crop in profitable amount only in our semi-arid regions. No attempt to produce a seed crop in the east should be made.
Value of Sods.—The character of the sods is a faithful index of the condition of the soil in any region adapted to grass. The value of heavy sods to a soil cannot be overestimated. They not only give to a farm a prosperous appearance, but our country's agriculture would be on a much safer basis if heavy coverings of grass were more universal. We do not hold the legumes in too high esteem, but the emphasis placed upon their ability to appropriate nitrogen from the air has caused some land-owners to fail in appreciation of the aid to soil fertility that may be rendered by the grasses. One often hears the statement that they can add nothing to the soil, and this is serious error. They add all that may be given in the clovers, excepting nitrogen only, and that is only one element of plant-food, important though it be. A great part of the value of clover lies in its ability to supply organic matter to the soil and to improve physical condition by its net-work of roots. Heavy grass sods furnish a vast amount of organic matter which not only supplies available plant-food to succeeding crops, but in its decay affects the availability of some part of the stores of potential fertility in the land.
Prejudice against Timothy.—Timothy, among the grasses, is especially in disrepute as a soil-builder, and yet its value is great. The belief that timothy is hard on land is based upon observation of bad treatment of this grass. There is a common custom of seeding land down to timothy when it ceases to have sufficient available plant-food for a profitable tilled crop, and usually this is the third year after a sod has been broken. The seeding is made with a grain crop that needs all the commercial fertilizer that may chance to be used. Clover may be seeded also, and on a majority of farms it fails to thrive when sown. If clover does grow, the succeeding crop of timothy may be heavy. If clover does not grow, the timothy is not so heavy. The seeding to grass is made partly because a tilled crop would not pay, and partly because a hay crop is needed. It comes in where other crops cannot come with profit, and it produces fairly well, or very well, the first year it occupies the ground by itself. With little or no aid from manure or commercial fertilizer, it adds much to the supply of organic matter in the soil, and it produces a hay crop that may be made into manure or converted into cash.
If the sod were broken the following spring, giving to the soil all the after-math and the mass of roots, its reputation with us would be far better than it is. This would be true even if it had received little fertilizer when seeded or during its existence as a sod, not taking into account any manure spread upon it during the winter previous to its breaking for corn. But the rule is not to break a grass sod when it is fairly heavy. The years of mowing are arranged in the crop-rotation to provide for as many harvests as promise immediate profit. On some land this is two years, and not infrequently it is three. Where farms are difficult of tillage, it is a common practice to let timothy stand until the sod is so thin that the yield of hay is hardly worth the cost of harvesting. Then the thin remnant of sod is broken for corn or other grain, and the poor physical condition of the soil and the low state of available fertility lead to the assertion that timothy is hard on the soil. This is a fair statement of the treatment of this plant on most farms.
Object of Sods.—The land's share of its products cannot be disregarded without loss. The legumes and grasses come into the crop-rotation primarily to raise the percentage of organic matter that the land may appropriate to itself within the rotation. Some of the crops usually are for sale from the farm. Most of the crops require tillage, and that is exhaustive of the store of humus. A portion of the time within the rotation belongs to a crop that increases the supply of vegetable matter, unless manure is brought from an outside source. Sods lend themselves well to this purpose because they afford some income, in pasturage or hay, while filling the soil with vegetation. The tendency is to forget the primary purpose of sods in the scheme, and to ignore the requirement of land respecting a due share of what it produces. Attention centers upon the product that may be removed. The portion of the farm reduced in productive power for the moment goes to grass, while the labor and fertilizers are concentrated upon the fields that are broken for grain and vegetables. The removal of all the crop at harvest, and probably the pasturing of after-math, are the only matters of interest that the fields, depleted by cultivation and seeded down to grass, have for the owner until the poor hay yield and the need of a sod for corn draw attention again to them.