Cover Crops Integration with Nitrogen Management for Dryland Cotton in Sandy Ultisols

One of the many benefits of cover crops (CCs) is nutrient provision, which can be optimized by synchronizing the nutrient release from residue decomposition with the demand for subsequent cash crops. This study is part of a multistate research (13 states) to measure cotton lint yield in response to cover cropping as a nutrient management strategy. This research-based information will help farmers optimize nitrogen (N) fertilization when integrating CCs into their production systems. A two-year field trial was conducted in 2021 and 2022 with four cover crop treatments (cereal rye, crimson clover, mixtures of cereal rye and crimson clover, and control) and five N rates (0, 45, 90, 135, and 180 kg N ha-1) in a cotton production system. Nutrient release patterns were determined with litter bag methods. Soil samples were collected and analyzed for physio-biogeochemical properties underlying soil functions. Cotton lint yield and nutrient use efficiency (NUE) were measured. Integrating cover crops did not change lint yield, while applying N rates at 90 and 45 kg N ha-1 increased the yield in 2021 and 2022, respectively, beyond which the yields did not change. However, the NUE decreased with increasing N rates. Planting crimson clover decreased the NUE in 2022, which was improved by incorporating cereal rye. These results indicate that maximum lint yield and NUE of dryland cotton could be achieved with a moderate N rate (45 kg N ha-1) under cover crop mixtures