Integrated crop‐livestock systems result in less nitrate leaching than ungrazed crop systems in North Florida

Abstract

AbstractIntegrated crop‐livestock systems provide an array of benefits to agricultural systems, including a reduction in nitrogen (N) leaching. A farm approach to integrate crops and livestock is the adoption of grazed cover crops. Moreover, the addition of perennial grasses into crop rotations may improve soil organic matter and decrease N leaching. However, the effect of grazing intensity in such systems is not fully understood. This 3‐year study investigated short‐term effects of cover crop planting (cover and no cover), cropping system (no grazing, integrated crop‐livestock [ICL], and sod‐based rotation [SBR]), grazing intensity (heavy, moderate, and light grazing), and cool‐season N fertilization (0, 34, and 90 kg N ha−1) on NO3‐N and NH4‐N concentration in leachate, and cumulative N leaching by using 1.5‐m deep drain gauges. The ICL was a cool‐season cover crop‐cotton (Gossypium hirsutum L.) rotation, whereas SBR was a cool‐season cover crop‐bahiagrass (Paspalum notatum Flüggé) rotation. There was a treatment × year × season for cumulative N leaching (p = 0.035). Further contrast analysis indicated that cover crops decreased cumulative N leaching compared to no cover (18 vs. 32 kg N ha−1 season−1). Nitrogen leaching was lesser for grazed compared to nongrazed systems (14 vs. 30 kg N ha−1 season−1). Treatments containing bahiagrass had lesser NO3‐N concentration in leachate (7 vs. 11 mg L−1) and cumulative N leaching (8 vs. 20 kg N ha−1 season−1) compared to ICL systems. Adding cover crops can reduce cumulative N leaching in crop‐livestock systems; moreover, warm‐season perennial forages can further enhance this benefit.