Soil water dynamics under a warm-season cover crop mixture in continuous wheat

Cover crop technology can potentially benefit monoculture wheat systems in the semi-arid US Southern Great Plains, but the biggest hurdle in such regions where evapotranspiration exceeds precipitation is soil water. Cover crop impact on soil water use and availability is a major cause for concern in water-limited environments. The objective of this study was to evaluate the impact of cover crops, grazing, and intercrops on soil water dynamics under rainfed conditions. Seven treatments were evaluated, including conventional tillage (CT) and combinations of no-tillage (NT) with a cover crop mixture, grazed cover crops, and/or cash crop intercropping. The three-year study was conducted on a long-term NT continuous wheat system in the Texas Rolling Plains. Despite dry periods, the cover crop mixture produced 2141 to 3503 kg ha(-1) dry herbage mass. Stored soil water was significantly lower within 60 days after planting for cover crop compared to no cover crop treatments. Stored soil water was 22-26% lower in cover crop plots at time of termination. In the final two years of the study, the positive change in stored soil water from cover crop termination to wheat planting was two to four times greater for cover crop treatments compared to non-cover crop treatments. The greater infiltration and water capture after termination has the potential to make up for the loss in soil water that cover crops used.