Intercropping Irrigated Corn with Annual Legumes for Fall Forage in the High Plains

Abstract

Many farmers in the central High Plains graze corn (Zea mays L.) aftermath and are looking at ways to improve the quality and amount of this fall pasture resource. However, no information is available on intercropping annual legumes with irrigated corn in the region. Our objective was to determine the most appropriate pasture legume species that could be used for an irrigated corn–legume system. To accomplish this, field experiments were conducted under irrigation at four sites in Wyoming. Eight legume species planted with corn were compared with monoculture corn under weed‐free and weedy conditions. Under weed‐free conditions, corn grain yields were reduced by the presence of legume in some treatments while others were comparable to the check yields. Black medic (Medicago lupulina L.) did not reduce corn yields, but barrel medic (M. truncatula Gaertn.) and sphere medic (M. sphaerocarpus L.) reduced corn yields by 17%. Corn yields were reduced 62% by the presence of weeds regardless of legume species. Legumes did not suppress weed growth. Barrel medic produced the most forage in July; however, there was little difference among species by November. In November, when corn stalks would be grazed, black medic and yellow sweetclover (Melitotus officinalis Lam.) produced the highest quality forage. These results indicate that a mostly weed‐free field is required to maximize corn and legume production. Of the legume species evaluated, black medic appears to offer the greatest potential for intercropping with irrigated corn in the central High Plains.