This is one of the most essential operations in the culture of the earth, and requires to be performed with the greatest care. Whatever, therefore, may be the design of the farmer, or the destination of the ground, thus moved, it ought never to be ploughed in a wet state ; because the soil cannot be improved by such labour. Farther, the plough ought to be carried to a considerable depth into the soil; and, if one turning be not sufficient, it will be advisable to pass another plough over the same furrow, so that the land may be effectually stirred; when, being thus exposed to the air, its fertilizing properties will not only be considerably augmented, but all perennial weeds will be completely eradicated.-Deep ploughing, however, is unnecessary for land that has been recently manured with lime or marle; but, on exhausted soils, it is uncommonly beneficial, and has, therefore, been generally recom-mended by the most skilful. husbandmen.
Ploughing increases the food of plants ; as it opens the soil for the reception, of vegetable aliment from the air; and, the surface being consequently enlarged, a greater portion of land is thus exposed to its influence. Farther, by breaking up the ground, it it be too solid, and rendering it firm, in case it be too light, this operation greatly tends to improve the earth ; and' as weeds and other vegetable substances are thus reduced to a state of putrefaction, it promotes the nourishment of the new roots. Lastly, ploughing removes too great humidity, by forming the land into ridges (which see), and contributes to the eradication of weeds ; as it first causes their seeds to vegetate ; and, afterwards tearing up the young plants, exposes their roots to the drought; in consequence of which, they are deprived of their vegetative power.