(1) Secondary sowing of crops on a field after the main crop is harvested, resulting in a second harvest in the same year. Secondary sowing permits a more productive use of land and a higher yield per unit of area.
Secondary sowing is widespread in regions with sufficient moisture and a long warm autumn and in irrigated farming. In Middle Asia, Transcaucasia, the Northern Caucasus, and the southern Ukraine, secondary sowing takes place after the harvest. For example, after winter barley is harvested, another grain crop is sowed—buckwheat, millet, early corn or peas—and a second crop of grain or verdure is obtained. In these areas and in the more northerly regions, sowing takes place after mowing: the first crop is harvested before it reaches maturity (for example, winter rye is harvested for green fodder) and feed cabbage or turnips are then grown.
(2) Sowing of the same crop on the same field for two or several years in a row. This type of sowing takes place in areas specializing in the cultivation of such crops as cotton, rice, and wheat. When there is adequate fertilizing and moisture, the yield of these crops is not reduced by repeated planting. This type of sowing is also used on outside fields, not used for crop rotation. An example is the growing of hemp for two or three years in a row on a well-manured hemp field.
REFERENCESDva urozhaia kormovykh kul’tur v god. Moscow, 1968. Zemledelie, 2nd ed. Edited by S. A. Vorob’ev. Moscow, 1972.
S. A. VOROB’EV