Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada.
North Florida Research and Education Center, University of Florida, Marianna, Florida, USA.
J Environ Qual. 2023 Jul-Aug;52(4):847-858. doi: 10.1002/jeq2.20474. Epub 2023 Apr 30.
Integrated 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 ) on NO -N and NH -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 season ). Nitrogen leaching was lesser for grazed compared to nongrazed systems (14 vs. 30 kg N ha season ). Treatments containing bahiagrass had lesser NO -N concentration in leachate (7 vs. 11 mg L ) and cumulative N leaching (8 vs. 20 kg N ha season ) 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.
种养结合系统为农业系统提供了一系列益处，包括减少氮（N）淋失。一种将作物和牲畜结合起来的农场方法是采用放牧覆盖作物。此外，在作物轮作中添加多年生草种可能会提高土壤有机质并减少 N 淋失。然而，这种系统中放牧强度的影响尚未完全了解。这项为期 3 年的研究调查了覆盖作物种植（有覆盖和无覆盖）、种植制度（无放牧、种养结合[ICL]和草地轮作[SBR]）、放牧强度（重牧、中牧和轻牧）和冷季 N 施肥（0、34 和 90 kg N ha）对渗滤液中 NO-N 和 NH-N 浓度以及使用 1.5 米深排水计测定的累积 N 淋失的短期影响。ICL 是一种冷季覆盖作物-棉花（Gossypium hirsutum L.）轮作，而 SBR 是一种冷季覆盖作物-雀稗（Paspalum notatum Flüggé）轮作。累积 N 淋失存在处理×年份×季节（p = 0.035）。进一步的对比分析表明，与无覆盖相比，覆盖作物减少了累积 N 淋失（18 比 32 kg N ha 季）。与非放牧系统相比，放牧系统的 N 淋失较少（14 比 30 kg N ha 季）。与 ICL 系统相比，含有雀稗的处理具有较低的渗滤液中 NO-N 浓度（7 比 11 mg L）和累积 N 淋失（8 比 20 kg N ha 季）。添加覆盖作物可以减少种养结合系统中的累积 N 淋失；此外，暖季多年生牧草可以进一步增强这种益处。
