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在美国东南部已广泛采用两熟制,因为它增加了单位面积产量,土地资源能得到最大限度地利用.Lewis等(1976)对此曾在美国东部做了调查,认为在东南部各州和南部玉米带的粮食生产最有利的复种制度是小麦或大麦+大豆.
In the southeastern United States, the two-cropping system has been widely adopted because it increases the yield per unit area and maximizes the utilization of land resources.Lewis et al. (1976) investigated this area in the eastern United States and concluded that in the southeastern states and southern The most favorable cropping system for grain production in the corn belt is wheat or barley + soybeans.