Deep and well-pulverized soils attract much more moisture, in every form, from the atmosphere, than shallow and compact soils. They, in fact, expose a much larger surface to the air. This is the reason why stirring the ground, even in the Summer drought, refreshes our fields of Indian corn.
CHAPTER XVII
INJURY OF LAND BY DRAINAGE.
Most Land cannot be Over-drained.—Nature a Deep drainer.—Over-draining of Peaty Soils.—Lincolnshire Fens; Visit to them in 1857.—56 Bushels of Wheat to the Acre.—Wet Meadows subside by Drainage.—Conclusions.
Is there no danger of draining land too much? May not land be over-drained? These are questions often and very naturally asked, and which deserve careful consideration. The general answer would be that there is no danger to be apprehended from over-draining; that no water will run out of land that would be of advantage to our cultivated crops by being retained. In other words, soils generally hold, by capillary attraction, all the moisture that is of any advantage to the crops cultivated on them; and the water of drainage would, if retained for want of outlets, be stagnant, and produce more evil than good.
We say this is generally true; but there are said to be exceptional cases, which it is proposed to consider. If we bear in mind the condition of most soils in Summer, we shall see that this apprehension of over-draining is groundless. The fear is, that crops will suffer in time of drought, if thoroughly drained. Now, we know that, in almost all New England, the water-table is many feet below the surface. Our wells indicate pretty accurately where the water-table is, and drains, unless cut as low as the surface of the water in the wells, would not run a drop of water in Summer.
Our farmers dig their wells twenty, and even fifty, feet deep, and expect that, every Summer, the water will sink to nearly that depth; but they have no apprehension that their crops will become dry, because the water is not kept up to within three feet of the surface.
The fact is, that Nature drains thoroughly the greater portion of all our lands; so that artificial drainage, though it may remove surplus water from them more speedily in Spring, cannot make them more dry in Summer. And what thus happens naturally, on most of the land, without injury, cannot be a dangerous result to effect by drainage on lands of similar character. By thorough-drainage, we endeavor to make lands which have an impervious or very retentive subsoil near the surface, sufficiently open to allow the surplus water to pass off, as it does naturally on our most productive upland.
OVER-DRAINING OF PEATY SOILS.
No instance has yet been made public in America, of the injury of peat lands by over-drainage; but there is a general impression among English writers, that peat soils are often injured in this way. The Lincolnshire Fens are cited by them, as illustrations of the fact, that these lands do not require deep drainage.
Mr. Pusey says, "Every one who is practically acquainted with moory land, knows that such land may be easily over-drained, so that the soil becomes dusty or husky, as it is called—that is, like a dry sponge—the white crops flag, and the turnip leaves turn yellow in a long drought."