Having considered, as thoroughly as the limited space available
permitted, the matter of plant foods, we must proceed to the equally
important one of how properly to set the table, on or rather in, which
they must be placed, before the plants can
use them. As was noted in the first part of the preceding chapter, most tillable soils contain the necessary plant food elements to a considerable extent, but only in a very limited degree in _available_ forms. They are locked up in the soil larder, and only after undergoing physical and chemical changes may be taken up by the feeding roots of plants. They are unlocked only by the disintegration and decomposition of the soil particles, under the influence of cultivation--or mechanical breaking up--and the access of water, air and heat. The great importance of the part the soil must play in every garden operation is therefore readily seen. In the first place, it is required to furnish all the plant food elements--some seven in number, beside the three, nitrogen, phosphoric acid and potash, already mentioned. In the second, it must hold the moisture in which these foods must be either dissolved or suspended before plant roots can take them up. The soil is naturally classified in two ways: first, as to the amount of plant food contained; second, as to its mechanical condition--the relative proportions of sand, decomposed stone and clay, of which it is made up, and also the degree to which it has been broken up by cultivation. The approximate amount of available plant food already contained in the soil can be determined satisfactorily only by experiment. As before stated, however, almost without exception they will need liberal manuring to produce good garden crops. I shall therefore not go further into the first classification of soils mentioned. Of soils, according to their variation in mechanical texture, I shall mention only the three which the home gardener is likely to encounter. Rocks are the original basis of all soils, and according to the degree of fineness to which they have been reduced, through centuries of decomposition by air, moisture and frost, they are known as gravelly, sandy or clayey soils. CLAY SOILS are stiff, wet, heavy and usually "cold." For garden purposes, until properly transformed, they hold too much water, are difficult to handle, and are "late." But even if there be no choice but a clay soil for the home garden, the gardener need not be discouraged. By proper treatment it may be brought into excellent condition for growing vegetables, and will produce some sorts, such as celery, better than any warm, light, "garden" soil. The first thing to do with the clay soil garden, is to have it thoroughly drained. For the small amount of ground usually required for a home garden, this will entail no great expense. Under ordinary conditions, a half-acre garden could be under-drained for from $25 to $50--probably nearer the first figure. The drains--round drain tile, with collars--should be placed at least three feet deep, and if they can be put four, it will be much better. The lines should be, for the former depth, twenty to thirty feet apart, according to character of the soil; if four feet deep, they will accomplish just as much if put thirty to fifty feet apart--so it pays to put them in deep. For small areas 2-1/2-inch land tile will do. The round style gives the best satisfaction and will prove cheapest in the end. The outlet should of course be at the lowest point of land, and all drains, main and laterals, should fall slightly, but without exception, toward this point. Before undertaking to put in the drains, even on a small area, it will pay well to read some good book on the subject, such as Draining for Profit and Draining for Health, by Waring. But drain--if your land requires it. It will increase the productiveness of your garden at least 50 to 100 per cent.--and such an increase, as you can readily see, will pay a very handsome annual dividend on the cost of draining. Moreover, the draining system, if properly put in, will practically never need renewal. On land that has a stiff or clay sub-soil, it will pay well to break this up--thus making it more possible for the water to soak down through the surface soil rapidly--by using the sub-soil plow. (See Chapter V.) The third way to improve clay soils is by using coarse vegetable manures, large quantities of stable, manures, ashes, chips, sawdust, sand, or any similar materials, which will tend to break up and lighten the soil mechanically. Lime and land plaster are also valuable, as they cause chemical changes which tend to break up clayey soils. The fourth thing to do in treating a garden of heavy soil is to plow, ridging up as much as possible, in the fall, thus leaving the soil exposed to the pulverizing influences of weather and frost. Usually it will not need replowing in the spring. If not plowed until the spring, care should be taken not to plow until it has dried out sufficiently to crumble from the plow, instead of making a wet, pasty furrow. The owner of a clayey garden has one big consolation. It will not let his plant food go to waste. It will hold manures and fertilizers incorporated with it longer than any other soil. SANDY SOIL is, as the term implies, composed largely of sand, and is the reverse of clay soil. So, also, with the treatment. It should be so handled as to be kept as compact as possible. The use of a heavy roller, as frequently as possible, will prove very beneficial. Sowing or planting should follow immediately after plowing, and fertilizers or manures should be applied only immediately before. If clay soil is obtainable nearby, a small area of sandy soil, such as is required for the garden, can be made into excellent soil by the addition of the former, applied as you would manure. Plow the garden in the fall and spread the clay soil on evenly, harrowing in with a disc in the spring. The result will be as beneficial as that of an equal dressing of good manure--and will be permanent. It is one of the valuable qualities of lime, and also of gypsum to even a greater extent, that while it helps a clay soil, it is equally valuable for a sandy one. The same is true of ashes and of the organic manures--especially of green manuring. Fertilizers, on sandy soils, where they will not long be retained, should be applied only immediately before planting, or as top and side dressing during growth. Sandy soil in the garden will produce early and quick results, and is especially adapted to melons, cucumbers, beans and a number of the other garden vegetables. GRAVELLY SOIL is generally less desirable than either of the others; it has the bad qualities of sandy soil and not the good ones of clay, besides being poorer in plant food. (Calcareous, or limestone pebble, soils are an exception, but they are not widely encountered.) They are not suited for garden work, as tillage harms rather than helps them. THE IDEAL GARDEN SOIL is what is known as a "rich, sandy loam," at least eight inches deep; if it is eighteen it will be better. It contains the proper proportions of both sand and clay, and further has been put into the best of mechanical condition by good tilth. That last word brings us to a new and very important matter. "In good tilth" is a condition of the soil difficult to describe, but a state that the gardener comes soon to recognize. Ground, continually and _properly cultivated_, comes soon to a degree of fineness and lightness at once recognizable. Rain is immediately absorbed by it, and does not stand upon the surface; it does not readily clog or pack down; it is crumbly and easily worked; and until your garden is brought to this condition you cannot attain the greatest success from your efforts. I emphasized "properly cultivated." That means that the soil must be kept well supplied with humus, or decomposed vegetable matter, either by the application of sufficient quantities of organic manures, or by green manuring, or by "resting under grass," which produces a similar result from the amount of roots and stubble with which the soil is filled when the sod is broken up. Only by this supply of humus can the garden be kept in that light, friable, spongy condition which is absolutely essential to luxuriant vegetable growth.
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