Management of Land Diverted from Crop Production. II. Annual Cover Crops and Fallow1

Abstract Cover crops belonging to the Cruciferae, Gramineae, and Leguminoseae families, summer fallow, and annual weed cover were compared in weed control and effect on the next year's corn (Zea mays L.) and sunflower (Helianthus annuus L.) crops. Corn yields were increased if legumes were present in the cover crop. Some grass‐legume mixtures gave more weed control at lower seed costs than pure legumes, and corn following some mixtures yielded as much as corn following pure legumes. Annual Cruciferae gave satisfactory performance at very low seed costs. Corn following most cover crops yielded considerably more than corn following annual weed cover. Sunflower yields following the cover crops did not differ significantly. Corn but not sunflower following summer fallow showed retarded growth and lighter green foliage than after cover crops. The symptoms disappeared in mid‐summer, but corn ear moisture was high at harvest. Concentrations of 14 chemical elements in corn and sunflower indicated that, except in P, composition of both crops responded similarly to cover crops and summer fallow. P concentration in corn plants after summer fallow was lower than after cover crops.