Winter cover crop production and water use in Southern Great Plains cotton

Cover crops can provide several ecosystem services in agricultural cropping systems. Benefits may be enhanced with increasing cover crop biomass production. In water-limited environments, feasibility of cover crop germination and production is not always certain. This study was conducted to determine differences in biomass production, water use, and water use efficiency (WUE) between monoculture cover crops and a mixture at Chillicothe, TX, in the Southern Great Plains under rainfed conditions in a continuous cotton (Gossypium hirsutum L.) cropping system over a 6-yr period. Evaluated cover crops included Austrian winter pea (Pisum sativum L.), crimson clover (Trifolium incarnatum L.), hairy vetch (Vicia villosa L.), hard red winter wheat (Triticum aestivum L.), and a grass/broadleaf mixture. Although cover crops were planted after optimum planting dates and under varying climatic conditions, biomass production was 2863, 2480, and 2301 kg ha(-1) for the mixture, pea, and vetch, respectively. Peas and the mixture were the most consistent, producing significantly greater biomass than wheat and clover but not more than vetch. The mixture resulted in greater WUE than wheat. Clover resulted in reduced biomass production and WUE than vetch, pea, and the mixture over the study period. A cover crop mixture did not produce significantly greater biomass or significantly increase water use efficiency compared with vetch and pea. Under dryland conditions, peas, vetch, and a mixture were shown to be viable cover crop options in Southern Great Plains cotton systems, performing as well as a wheat cover crop.