FALLOW, land ploughed and tilled, but left unsown usually for a year, in order, on the one hand, to disintegrate, aerate and free it from weeds, and, on the other, to allow it to recuperate. The "Sabbath rest" ordered to be given every seventh year to the land by Mosaic law is a classical instance of the "fallow." Improve ments in crop rotations and manuring have diminished the neces sity of the "bare fallow," which is uneconomical because the land is left unproductive, and because the nitrates in the soil uninter cepted by the roots of plants are washed away in the drainage waters. At the present time bare fallowing is, in general, only advisable on stiff soils and in dry climates. A "green fallow" is land planted with turnips, potatoes or some similar crop in rows, the space between which may be cleared of weeds by hoeing. The "bastard fallow" is a modification of the bare fallow, effected by the growth of rye, vetches, or some other rapidly growing crop, sown in autumn and fed off in spring, the land then undergoing the processes of ploughing, grubbing and harrowing usual in the bare fallow. (See CULTIVATION; ROTATION OF CROPS; DRY-FARM ING.)