Effect of Season and Plant Spacing on Yields of Intensively Managed Soybeans Under Tropical Conditions

Soybeans of the Hardee variety planted at 20 inches X 3 1/2 inches yielded over 40 bushels per acre when planted from mid-February to mid-September. The highest yields, exceeding 60 bushels per acre, were obtained from May and June plantings and the lowest, about 20 bushels per acre, from December and January plantings with 90,000 plants per acre in all cases. Yields can be increased markedly during the winter by increasing populations to about 200,000 plants per acre. Higher yields were obtained with 20-inch X 3 1/2-inch than with 30- inch X 2 1/3-inch or 40-inch X 1 3/4-inch spacings. Bean size and protein and oil contents were unaffected by plant spacing or season of the year. It is possible to produce two crops of soybeans yearly in Puerto Eico with a combined yield of over 100 bushels (6,000 pounds) per acre containing about 2,500 pounds of dry protein and 1,300 pounds of oil. Three crops with a total yield of 160 bushels per acre yearly are theoretically possible.