Drainage assists pulverization. It was Tull's theory that, by the comminution, or minute division, of soils alone, without the application of any manures, their fertility might be permanently maintained; and he so far supported this theory as, by repeated plowings, to produce twelve successive crops of wheat on the same land, without manure. The theory has received support from the known fact, that most soils are benefitted by Summer fallowing. The experiments instituted for the purpose of establishing this theory, although they disproved it, showed the great value of thorough pulverization. It is manifest that a wet soil can never be pulverized. Plowing clayey, or even loamy soil, when wet, tends rather to press it together, and render it less pervious to air and water.
The first effect of under-draining is to dry the surface-soil, to draw out all the water that will run out of it, so that, in early Spring, or in Autumn, it may be worked with the plow as advantageously as undrained lands in mid-Summer.
Striking illustrations of the benefits of thorough pulverization will be found in the excellent remarks of Dr. Madden, given in a subsequent chapter.
Drainage prevents surface-washing. All land which is not level, and is not in grass, is liable to great loss by heavy rains in Spring and Autumn. If the land is already filled with water, or has not sufficient drainage, the rain cannot pass directly downward, but runs away upon the surface, carrying with it much of the soil, and washing out of what remains, of the valuable elements of fertility which have been applied with such expense. If the land be properly drained, the water falling from the clouds is at once absorbed, and passes downwards, saturating the soil in its descent, and carrying the soluble substances with it to the roots, and the surplus water runs away in the artificial channels provided by the draining process. So great is the absorbent power of drained land, that, after a protracted drought, all the water of a heavy rainstorm will be drunk up and held by the soil, so that, for a day or two, none will find its way to the drains, nor will it run upon the surface.
Drainage lengthens the season for labor and vegetation. In the colder latitudes of our country, where a long Winter is succeeded by a torrid Summer, with very little ceremony by way of an intervening Spring, farmers have need of all their energy to get their seed seasonably into the ground. Snow often covers the fields in New England into April; and the ground is so saturated with water, that the land designed for corn and potatoes, frequently cannot be plowed till late in May. The manure is to be hauled from the cellar or yard, over land lifted and softened by frost, and all the processes of preparing and planting, are necessarily hurried and imperfect. In the Annual Report of the Secretary of the Board of Agriculture, of the State of Maine, for 1856, a good illustration of this idea is given: "Mr. B. F. Nourse, of Orrington, plowed and planted with corn a piece of his drained and subsoiled land, in a drizzling rain, after a storm of two days. The corn came up and grew well; yet this was a clayey loam, formerly as wet as the adjoining grass-field, upon which oxen and carts could not pass, on the day of this planting, without cutting through the turf and miring deeply. The nearest neighbor said, if he had planted that day, it must have been from a raft." Probably two weeks would be gained in New England, in Spring, in which to prepare for planting, by thorough-drainage, a gain, which no one can appreciate but a New England man, who has been obliged often to plow his land when too wet, to cut it up and overwork his team, in hauling on his manure over soft ground, and finally to plant as late as the 6th of June, or leave his manure to waste, and lose the use of his field till another season; and all because of a surplus of cold water.
Mr. Yeomans, of New York, in a published statement of his experience in draining, says, that on his drained lands, "the ground becomes almost as dry in two or three days after the frost comes out in Spring, or after a heavy rain, as it would do in as many weeks, before draining." But the gain of time for labor is not all. We gain time also for vegetation, by thorough-drainage. Ten days, frequently, in New England, may be the security of our corn-crop against frost. In less than that time, a whole field passes from the milky stage, when a slight frost would ruin it, to the glazed stage, when it is safe from cold; and twice ten days of warm season are added by this removal of surplus water.
Drainage prevents freezing out. Mr. John Johnston, of Seneca County, New York, in 1851, had already made sixteen miles of tile drains. He had been experimenting with tiles from 1835, and had, on four acres of his drained clayey land, raised the largest crop of Indian corn ever produced in that county—eighty-three bushels of shelled corn to the acre.
He states, that on this clayey soil, when laid down to grass, "not one square foot of the clover froze out." Again he says, "Heretofore, many acres of wheat were lost on the upland by freezing out, and none would grow on the lowlands. Now there is no loss from that cause."
The growing of Winter wheat has been entirely abandoned in some localities on account of freezing out, or Winter-killing; and one of the worst obstacles in the way of getting our lands into grass, and keeping them so, is this very difficulty of freezing out. The operation seems to be merely this: The soil is pulverized only to the depth of the plow, some six or eight inches. Below this is a stratum of clay, nearly impervious to water. The Autumn rains saturate the surface soil, which absorbs water like a sponge. The ground is suddenly frozen; the water contained in it crystallizes into ice; and the soil is thrown up into spicules, or honey-combs; and the poor clover roots, or wheat plants, are drawn from their beds, and, by a few repetitions of the process, left dead on the field in Spring. Draining, followed by subsoiling, lets down the falling water at once through the soil, leaving the root bed of the plants so free from moisture, that the earth is not "heaved," as the term is, and the plants retain their natural position, and awaken refreshed in the Spring by their Winter's repose.
There are no open ditches on under-drained land. An open ditch in a tillage or mowing-field, is an abomination. It compels us, in plowing, to stop, perhaps midway in our field; to make short lands; to leave headlands inconvenient to cultivate; and so to waste our time and strength in turning the team, and treading up the ground, instead of profitably employing it in drawing a long and handsome furrow the whole length of the field, as we might do were there no ditch. Open ditches, as usually made, obstruct the movement of our teams as much as fences, and a farm cut into squares by ditches, is nearly as objectionable as a farm fenced off into half or quarter-acre fields.