摘要：Between 1974 and 1983, intertemporal cost efficiency for u.s. field crops increased about 1.4 to 1.2% percent for corn, soybeans, and wheat and .2% per year for cotton. competitive advantage in 1983 was held by central Illinois and north central Iowa in corn, central Illinois in soybeans, the Washington Palouse and central North Dakota in wheat, and southern California in cotton relative to the other selected regions in the study. Scale economies exist in corn, soybean and wheat but not in cotton production.
