Contributions of Ground Cover, Dry Matter, and Nitrogen from Intercrops and Cover Crops in a Corn Polyculture System1

Abstract

AbstractContinuous corn (Zea mays L.) grown on sloping land and harvested for silage, returns few residues to the soil and leaves the soil unprotected against erosion for most of the year. Three field experiments were conducted on a Lima loam (a fine‐loamy, mixed, mesic Glossoboric Hapludalf) to determine the contributions from various intercrops and cover crops towards ground cover, dry matter, and N. In Exp. 1 and Exp. 2, the effects of intercrops and cover crops were measured by determining corn grain yields following the plow down of the various crops. Corn grain yields following the incorporation of various crops were compared to yields of corn where no cover crops had been incorporated but N rates of 0, 56 or 112 kg ha−1 had been applied. In Exp. 3, the effects of intercrops and cover crops on corn yields were measured over a 5‐yr period. First‐year corn grain yields were neither increased nor decreased as a result of seeding intercrops when the corn was 0.15 to 0.30 m high. All intercrop and cover crop treatments in Exp. 3 provided significantly more ground cover than the control treatment. Annual ryegrass (Lolium multiflorum Lam.), medium red clover (Trifolium pratense L.), and a combination of the two were the most effective in terms of ground cover and dry matter production.