Hairy Vetch as a Winter Cover Crop for Dryland Corn Production

Government agricultural policies, fossil fuel prices, and environmental concerns (soil erosion and water quality) could all greatly affect future use of corn (Zea mays L.) monocultures. As a possible alternative, an experiment was conducted to evaluate production of continuous corn as affected by hairy vetch (Vicia villosa Roth) used as a winter cover crop. The experiment was conducted for four years on a Crete-Butler silty clay loam (fine, montmorillonitic, mesic Pachic Argiustolls-Abruptic Argiaquolls) under rainfed conditions at Lincoln, Nebraska. The six treatments investigated were continuous corn produced with no cover crop, no N fertilizer, and no tillage (C); no cover crop or tillage but with 55 lb N/acre broadcast as NH₄NO₃ (N); corn no-till planted into growing hairy vetch with no fertilizer (V); hairy vetch disked in at corn planting, no fertilizer (D); hairy vetch retarded with contact herbicide before corn planting, no tillage, and no fertilizer (R); and hairy vetch killed at planting with herbicide, no tillage, and no fertilizer (K). Results indicated that corn grain yields where hairy vetch was incorporated into soil by disking before planting equaled or exceeded those of all other treatments. Plant N uptake and soil inorganic N data suggested that much of the N in incorporated hairy vetch residue was mineralized and taken up by corn during grain fill. Little N in chemically killed hairy vetch residues left on the soil surface apparently became available to corn, even after several years. These results suggested that incorporating hairy vetch before planting corn usually provided avail- able N equal to, or greater than, that provided by 55 lb fertilizer N per acre. Lack of cultivars that will reseed themselves and the potential for reduced stored soil water at corn planting may restrict use of hairy vetch in drier temperate regions.