The Iowa Agricultural Experiment station has grown a number of different varieties of soy beans each year since 1910. It finds the crop very dependable, the better varieties producing yields of from 15 to 25 bushels of seed, or 2 1/2 to 3 1/2 tons of hay per acre In most seasons. The soy bean has a large number of uses as a hay crop, for seed, for silage, and tor pasturing with com, and it Is well suited to Iowa's climate and soil.
Hughes, H. D. and Wilkins, F. Scott, "Soy Beans in Iowa" (1920). Circular. Paper 65.