Crops and Methods for Soil Improvement Part 11

All the Nitrogen from Clover.--The Pennsylvania station has shown in a test of thirty years that when good clover is grown in a four-years'

rotation of corn, oats, wheat, and clover, the fertility of the naturally good clay loam soil may be maintained, and even slightly increased, without the use of any manure or purchased nitrogen.

Phosphoric acid and potash have been applied, and the clover hay crop has been taken off the land. This result has been possible only by means of good clover sods. If there had been no applications of phosphoric acid and potash, the clover would have failed to maintain fertility, as is proved by other plats in this experiment. No one should continue to depend upon such a scheme of keeping land fertile whenever he finds that the clover is not thriving.

Method of applying Fertilizers.--If a fertilizer is used in small amount with the purpose of merely giving the plants a start, it should be near the seed. If the application is heavy, and the roots of the plants spread upon all sides, the fertilizer, as a rule, should be applied to all the ground, and should be mixed with the surface soil.

This puts the plant-food where needed, and saves from danger of injury to the seed through contact. A seeming exception may be found in the case of the potato, but usually some close tillage confines its roots to the row for a time. Experience indicates that when a potato fertilizer does not exceed 500 pounds per acre, it may well be put into the row, but a heavier application should be divided, one half being broadcasted or drilled into the surface, and the other half of the application being made in the row.

An Excess of Nitrogen.--Too much nitrogen, due to heavy manuring or other cause, produces an excessive growth of stalk or straw, at the expense of grain production, in the case of corn, wheat, and other cereals. It produces a rank growth of potato vines and partial failure of the crop of tubers. It produces a tender growth of straw or vine that invites injury from fungous diseases. It is the rule that soils have a deficiency in nitrogen, but when there is an excess, the best cure comes through use of such crops as timothy, cabbage, and ensilage corn. Heavy applications of rock-and-potash fertilizers a.s.sist in recovery of right conditions, but are not wholly effective until exhaustive crops have removed some of the nitrogen.

CHAPTER XXI

TILLAGE

Desirable Physical Condition of the Soil.--Successful cropping of land is dependent upon favoring soil conditions. The plants to be grown must have ease in root extension, so that their food may be found. There must be moisture to hold the food in solution. There must be air. There must be destruction of plants that would be compet.i.tors of the ones desired. A soil rarely is in prime condition for the planting and growth of any crop without some change in its structure by means of tillage, and it does not remain in the best condition for any long period of time. If the number of plants required per acre for a crop is relatively small, tillage of the soil is continued after planting. If the necessary number makes tillage impossible, there is some loss in conditions most favorable to the plant. The particles of soil settle together, and there is loss of water at the surface. Most plants want a mellow soil, and tillage is in large part an effort to make and to keep the condition of the soil friendly to plant life in this respect. The wide variation in methods of tillage are due to the great differences in the texture and structure of soils, and to the habits of plants, and skill in selection of methods is a measure of the intelligence used in farming.

The Breaking-plow.--Land containing enough clay to give it an excellent soil inclines to become firm. During the growth of a crop, when plant roots fill the soil and prevent deep stirring, the particles pack closely together, limiting the power of the land to make fertility available. The presence of organic matter counteracts, in part, this packing tendency, but there are few soils that remain permanently mellow. The breaking-plow is used to loosen the soil, and to undo the firming that has been taking place while plant roots prevented deep tillage. At the same time the plow may be used to bury organic matter below the surface, affording a clean seed-bed. In some soils it has value in bringing inert soil to the surface, and in mixing the soil const.i.tuents.

Types of Plows.--The kind and condition of the soil, and the character of the crop, determine the type of plow to be used. A plow with a short and quite straight moldboard does not bury manure and turf in the bottom of the furrow so completely as is the case with a long, curved moldboard. The organic matter should be distributed throughout all the soil. On the other hand, it is essential to some plants that they have a fine seed-bed, and one whose surface is free from tufts of gra.s.s. The long moldboard is preferred in breaking a sod for corn. Its use in plowing for all crops is more general than it should be, the gain in pulverization of the furrow-slice, due to the curve, and the neatness in appearance of the plowed land, inducing its use.

The disk plow has been used chiefly in soils not requiring deep plowing. It pulverizes better than a moldboard plow, and buries trash more easily.

[Ill.u.s.tration: Deep tillage.]

The device for using two disks to turn a single furrow-slice rests upon a sound principle. This plow may be set to run deeper than moldboard plows go, and it mixes well all the soil that it turns. The disks are so hung that the mixing of all the soil to a depth of twelve or fifteen inches is admirable. The deep-tilling plow does not bury the organic matter in the bottom of the furrow, and thereby permits the deepening of the soil without bringing an undue amount of subsoil to the surface.

Subsoiling.--The theory of subsoiling always has been captivating. Most soils are too shallow, inviting injury from drouth. Enthusiasm regarding subsoiling comes to large numbers of farmers at some time in their experience, and a great number of subsoil plows have been bought.

The check to enthusiasm is the fact that few men ever have seen such a plow worn out. Some reasons are as follow:

(_a_) The subsoil at time of spring-plowing rarely is dry enough for good results, and there is danger of puddling; (_b_) the subsoil often is too dry and hard in late summer, when rains permit easy breaking of the top soil for fall grain; (_c_) the work doubles the labor and time of plowing, and (_d_) the subsoil soon settles together because it contains little organic matter.

Subsoiling is generally approved and little practiced. Land at plow-depth becomes packed by the tramping of horses upon it and the pressure of the plow, when the plowing is done at the same depth year after year, and in some soils subsoiling has been found distinctly valuable.

Time of Plowing.--In great measure the time of plowing is determined by the effect upon soil moisture, and is discussed in the next chapter.

Method of Plowing.--The depth of plowing should be fixed largely by the amount of organic matter in the soil. It is essential that a good percentage of this material should be mixed throughout the soil, and when it is in scant supply, the depth of plowing usually should not be great. Fertile soils should be plowed deep for their own good, and thin soils should be deepened gradually, as sods and manures afford a supply of humus-making material. Even when manure is used liberally in a single application on a poor soil, a large amount of inert subsoil should not be thrown upon the surface. The manure goes out of reach of the greatest need, which is in the surface soil where plant-life starts. A gradual process of deepening the soil is to be preferred, but such deepening should not be neglected. The subsoil is a store of inert fertility that should not remain dormant.

It may not do to say that the success of the best farmers is due to thoroughness in plowing, but it is true that the more successful ones are insistent that the plowing be absolutely thorough. Every inch of the soil should be stirred to a certain depth, and that requires a plow so set that it does not turn a furrow-slice much wider than the point can cut. Evenness in depth and width of furrow is seen in good plowing.

The Disk Harrow.--The purpose of the plow is to break up the soil so that it will be crumbly and mellow. The frequency with which land should be thoroughly stirred to full plow-depth depends upon the condition of the soil and the character of the crops. Oftentimes a disk or cutaway harrow may replace the plow. Its action is the same as that of the plow, loosening and turning the soil over. When land has had a good plowing within the year, and has not become compact, stirring to a depth of four inches may give a better seed-bed for some crops than could be made by use of a plow. This is true of land that has produced a cultivated crop and is being prepared for a fall-seeding. The gain in time of preparing ground for oats in the spring makes the use of the disk or cutaway harrow profitable on mellow corn-stubble land.

There is temptation to carry the subst.i.tution of the disk harrow for the breaking-plow too far. Its use alone would have the same effect as poor plowing, reducing the depth of the soil. The surface soil, down to plow-depth, is the chief feeding-ground for plants because it is kept in good tilth by organic matter and tillage. The depth of this soil affects the amount of available plant-food and water. The duration of time between deep plowings depends upon the soil and the crops.

Experience shows that when land has been broken for corn or potatoes or beans or similar crop, the one plowing may be sufficient for a succeeding crop. If gra.s.s is not seeded with the succeeding crop, it is best to give another thorough plowing before seeding to gra.s.s in August if the soil is heavy, but in naturally loose soils a disk harrow makes a better seed-bed.

Two influences favor such undue dependence upon a disk harrow that a soil may become shallow: the cost of preparing the seed-bed is reduced, and the saving in moisture may give a better stand of plants when the harrow takes the place of the plow. The immediate productiveness of a crop is not an a.s.surance that the method is right: consideration for the good of the land must be shown. Depth of soil is a requirement of a good agriculture, and deep plowing is a means to that end. The looseness of the soil and the character of the season may make subst.i.tution right in one instance and wrong in another. Deep soils, well filled with organic matter, will bear shallow preparation of a seed-bed more frequently than thin soils, and yet it is the latter that may profit most by having its best part kept near the surface at the time a new sod must be made. The disk harrow has some place as a subst.i.tute for a plow, but when its use results in making a soil more shallow, the harm is a most serious one.

Cultivation of Plants.--If a soil would remain mellow throughout the season, there usually would be no reason to disturb the roots of plants by any deep stirring, and all tillage would be only deep enough to make a mulch of earth for the retention of moisture and to destroy all weeds. Soils containing enough clay to make them retentive of moisture become too compact when rains beat upon the ground, as usually happens after the planting of spring crops. A deep and close cultivation of corn and potato plants after they appear in the row helps to restore the condition created by the plow and harrow, and often is the best practice. There is some sacrifice of roots, but the gain far exceeds the loss. It may be necessary to give a second such cultivation when a clay soil is deficient in organic matter, but the root-pruning is a handicap.

Controlling Root-growth.--The exception to the rule that plant-roots should not be pruned by deep cultivation is found in the case of a close soil in a wet season. The plants extend their roots only in the soil at the surface because the ground is soaked with water nearly all the time. They cannot form far enough below the surface to withstand a drouth that may follow the wet weather. Good tillage in such a case demands the pruning of the roots and the airing of the soil when the ground is dry enough to permit such stirring, and the plants then extend their roots in the lower soil where they rightly belong.

Judgment is required to decide when such tillage is desirable, but judgment is needed all the time in farming. When a continued period of wet weather affects the position of the plant-roots, it rarely is advisable not to risk deeper tillage than is given in a normal season.

Underdrainage helps to prevent such ill-effect of continued rains in the early part of a plant's life-time.

Elimination of Compet.i.tion.--Weeds pump the water out of the soil, use up available plant-food, and compete for the sunlight. Tillage is given for several reasons, and one is the destruction of weeds. A weeder which stirs the soil only an inch or two deep is an excellent destroyer of weeds when they are starting, but after the weeds are well-rooted, the weeder acts only as a cultivator for the plants that should be destroyed. Modern cultivators have fine teeth that let the surface remain nearly level, and they do their best work when the weeds are small. The use of "sweeps" should be more general. The blades are so placed that they slip under the surface, letting the soil fall back so that a mulch is formed.

Length of Cultivation.--Most tilled crops grow rapidly until they shade and mulch the soil. Tillage should continue, if possible, until this occurs. The exception is in the case of orchard trees and other plants that should not have their period of growth extended late in the fall.

Good tillage tends to increase the lateness of a crop by encouraging growth. The new wood of trees may not become hardy enough to withstand the frost of winter if tillage is continued. Early maturity is hastened by exhaustion of soil moisture and plant-food.

CHAPTER XXII

CONTROL OF SOIL MOISTURE

Value of Water in the Soil.--The amount of water in the soil each day of the growing season determines in large measure the possibility of securing a profitable crop from land. Observant farmers have noticed oftentimes that the differences in yields on the farms of a region are less in a wholly favorable season than in one of deficient rainfall.

The skill of the farmer in conserving the moisture supply in a wet season is less well repaid because it is less needed. The poverty of a worn soil is less marked in a favorable season. The land is accounted poor because the supply of plant-food is inadequate for a drouthy year in which a considerable percentage of the time produces little growth, but most agricultural land has enough plant-food for a fairly good crop when water is present all the time to carry daily supplies into the roots. It is the amount of moisture in the soil that is the limiting factor in the case of most land that is not in a high state of productiveness.

The Soil a Reservoir.--The rains of the summer rarely are adequate to the needs of growing plants. Some water runs off the surface, some pa.s.ses down through crevices beyond the effect of capillary attraction, and much quickly evaporates. The part that becomes available is only a supplement to the store of water made by the rains of the fall, winter, and early spring.

If the soil were viewed as a medium for the holding of water to meet the daily needs of plants, and were given rational treatment on this basis, a long step toward higher productiveness would have been taken.

As has been stated, rotted organic matter gives a soil more capacity for holding water. It is an absorbent in itself, and it puts clays and sands into better physical condition for the storage of moisture. An unproductive soil may need organic matter for this one reason alone more than it may need actual plant-food.

Fall-plowing for a spring crop enables land to withstand summer's drouth if it gains in physical condition by full exposure to the winter's frost. It is in condition to take up more water from spring rains than would be the case if it lay compact, and it does not lose water by the airing in the spring that plowing gives.

Early spring-plowing leaves land less subject to drouth than does later plowing. As the air becomes heated, the open s.p.a.ces left by the plowing serve to hasten the escape of moisture. If a cover crop is plowed down late in the spring, the material in the bottom of the furrow makes the land less resistant to drouth because the union of the top soil with the subsoil is less perfect, and capillary attraction is r.e.t.a.r.ded. It is usually good practice to sacrifice some of the growth of a cover crop, even when organic matter is badly needed, and to plow fairly early in the spring in order that the moisture supply may be conserved.

The Land-roller.--The breaking-plow is a robber of soil water when used in warm weather. The air carries the water away rapidly. The air-s.p.a.ces are large. The corrective of this condition is the land-roller. It presses the soil together, driving out the excess of air. Large crumbs are pressed down into the ma.s.s, and are kept from drying into hard clods. The roller never should be used on land when fresh-plowed in a moist condition, and it is not needed after fall-plowing, or early spring-plowing in most instances, but land broken when the season is advanced should be rolled before much water evaporates.

[Ill.u.s.tration: Making an earth mulch in a New York orchard.]

The Plank-drag.--An excellent implement on a farm is the plank-drag. It is usually made of over-lapping heavy planks, and when floated over the surface, it both pulverizes and packs the soil. The effectiveness is controlled by the weight placed upon it, and oftentimes the drag is to be preferred to the roller.

The Mulch.--In conserving the supply of water in the soil the mulch plays an important work. The dry air is constantly taking up the water from the surface of land, and when the surface is drier than the soil below, the moisture moves upward if there is no break in the structure of the surface soil. The mulch is a covering of material that does not readily permit the escape of water.

The only available material for a mulch in most instances is the soil itself. Experience has taught that when the top layer of soil, to a depth of two or three inches, is made fine and loose, the water beneath it cannot escape readily. It is partly for this reason that the smoothing-harrow should follow the roller after land has been plowed.

The plow is used to break up the soil into crumbs that will permit air to enter. The loosening is excessive when the planting must follow soon, permitting rapid escape of water. The roller or plank-drag is employed to compress the soil, and to crush crumbs of soil that are too large for good soil conditions. The harrow follows to make a mulch of fine, loose soil at the surface to a.s.sist in prevention of evaporation.

A sandy soil will retain its mulch in effective condition for a longer time than a fine clay, if no rain falls. When the air is laden with moisture, clay particles absorb enough water to pack together and form an avenue for the rise of water to the surface, where the dry air has access to it.

Mulches of Foreign Material.--The truth that moisture is a leading factor in soil productiveness is evidenced by the value of straw and similar material as a mulch. A covering of straw around trees in an orchard, or bush fruits, or such plants as the potato, may give better results than an application of fertilizer when no effort is made to prevent the escape of water. People so situated that little attention can well be given to the fruit and vegetable garden obtain good results by replacing tillage with a substantial mulch that keeps the soil mellow, prevents weed growth, and retains an abundant supply of water.

In grain-producing districts where all the straw is not needed as an absorbent in the stables its use as a mulch on thin gra.s.s lands, or wheat-fields seeded to gra.s.s, is more profitable than conversion into manure by rotting in a barnyard. The straw affords protection from the sun, and aids in the conservation of soil water, when scattered evenly in no larger amount than two tons per acre, and a less amount per acre has value. The sod is helped, and as the straw rots, its plant-food goes into the soil.

Plowing Straw Down.--The practice of plowing straw under as a manure is unsafe, when used in any large quant.i.ty per acre. It rots slowly, and while lying in the bottom of the furrow it cuts off the rise of water from the subsoil which is a reservoir of moisture for use during drouth.

The Summer-fallow.--Bare land loses in total plant-food, but may make a temporary gain in available fertility. The practice of leaving a field uncropped for an entire season has been abandoned in good farming regions. Where moisture is in scant supply, and a soil is thin, there continue instances of the summer-fallow. In a crop-rotation containing corn and wheat, the corn-stubble land is left unbroken until May or June, and then plowed. In August it is plowed again, and fitted for seeding to wheat. The practice favors the killing of weeds, and the soil at seeding time may contain more water than would have been the case if a crop had been produced, because its mellow condition enables the farmer to hold within it nearly all the moisture that a shower may furnish after the second plowing.