The first step in the preparation of land, after it has been thoroughly cleared and subdued of forest or previous vegetation, is to attend to the drainage. All land that is springy, low, and "sour," or that holds the water in puddles for a day or two following heavy rains, should be thoroughly underdrained. Draining also improves the physical condition of the soil even when the land does not need the removal of superfluous water. In hard lands, it lowers the water-table, or tends to loosen and aerate the soil to a greater depth, and thereby enables it to hold more water without injury to plants. Drainage is particularly useful in dry but hard garden lands, because these lands are often in sod or permanently planted, and the soil cannot be broken up by deep tillage. Tile drainage is permanent subsoiling.
Hard-baked cylindrical tiles make the best and most permanent drains. The ditches usually should not be less than two and one-half feet deep, and three or three and one-half feet is often better. In most garden areas, drains may be laid with profit as often as every thirty feet. Give all drains a good and continuous fall. For single drains and for laterals not over four hundred or five hundred feet long, a two and one-half inch tile is sufficient, unless much water must be carried from swales or springs. In stony countries, flat stones may be used in place of tiles, and persons who are skillful in laying them make drains as good and permanent as those constructed of tiles. The tiles or stones are covered with sods, straw, or paper, and the earth is then filled in. This temporary cover keeps the loose dirt out of the tiles, and by the time it is rotted the earth has settled into place.
In small places, ditching must ordinarily be done wholly with hand tools. A common spade and pick are the implements usually employed, although a spade with a long handle and narrow blade, as shown in Fig. 79, is very useful for excavating the bottom of the ditch.
In most cases, much time and muscle are wasted in the use of the pick. If the digging is properly done, a spade can be used to cut the soil, even in fairly hard clay land, with no great difficulty. The essential point in the easy use of the spade is to manage so that one edge of the spade always cuts a free or exposed surface. The illustration (Fig. 80) will explain the method. When the operator endeavors to cut the soil in the method shown at A, he is obliged to break both edges at every thrust of the tool; but when he cuts the slice diagonally, first throwing his spade to the right and then to the left, as shown at B, he cuts only one side and is able to make progress without the expenditure of useless effort. These remarks will apply to any spading of the land.
In large areas, horses may be used to facilitate the work of ditching. There are ditching plows and machines, which, however, need not be discussed here; but three or four furrows may be thrown out in either direction with a strong plow, and a subsoil plow be run behind to break up the hard-pan, and this may reduce the labor of digging as much as one-half. When the excavating is completed, the bottom of the ditch is evened up by means of a line or level, and the bed for the tiles is prepared by the use of a goose-neck scoop, shown in Fig. 79. It is very important that the outlets of drains be kept free of weeds and litter. If the outlet is built up with mason work, to hold the end of the tile intact, very much will be added to the permanency of the drain.