Despite the potential to increase soil organic matter, cycle soil nutrients, and suppress weeds, there is a concern that cover crops (CCs) soil water use negatively impacts subsequent crops in water-limited environments. Cover crop management practices such as planting and termination timing may mitigate the detrimental impacts of CCs in semi-arid cropping systems. To determine the effects of CCs under water-limited environments, we evaluated the total CC biomass produced in the fall and spring, soil water content during the subsequent maize growing season, weed density and biomass, crop residue, and soil nutrients at the maize V6 development stage, and maize productivity. The experiment was conducted under a wheat-maize-fallow rotation at two sites (Grant and North Platte, NE) during 2016−2017 and 2017−2018. Treatments consisted of three planting timings after winter wheat harvest and three CC termination timings and fallow (no CCs) before maize establishment. Planting CCs shortly after winter wheat harvest increased CC biomass in the fall and early spring compared to late planting. Cover crops terminated early in the spring reduced weed biomass (−70 %), while CCs terminated late in the spring reduced both weed density (−56 %) and biomass (−82 %) compared to fallow. Due to above-normal precipitation during the experiment, soil water measured at 0−20 cm soil depth was impacted by CCs only at Grant 2016−2017. Cover crops terminated late in the spring increased crop residue biomass but decreased total nitrogen at 0−10 cm soil depth by 17 %, and decreased soil nitrate at the 10−20 cm soil depth up to 26 % compared to fallow. Cover crops planted late in the summer (August) and terminated late in the spring (May) had the most detrimental impact on maize grain yield. Late termination of CCs in the spring reduced corn grain yield by up to 20 % compared to fallow. Despite enhanced weed suppression and crop residue, CCs decreased soil nitrogen and maize grain yield, especially when terminated late in the spring. Producers in semi-arid regions of the Great Plains willing to incorporate CCs should use caution when selecting management strategies for their CCs to minimize maize grain yield and economic losses.

尽管有可能增加土壤有机质、循环土壤养分和抑制杂草，但人们担心覆盖作物 (CCs) 土壤水分的利用会对缺水环境中的后续作物产生负面影响。覆盖作物管理实践，如种植和终止时间，可以减轻半干旱作物系统中 CCs 的不利影响。为了确定限水环境下 CC 的影响，我们评估了秋季和春季产生的总 CC 生物量、随后玉米生长季节的土壤含水量、杂草密度和生物量、作物残留物和玉米 V6 的土壤养分发展阶段，和玉米生产力。该试验是在 2016-2017 年和 2017-2018 年期间在两个地点（格兰特和北普拉特，内布拉斯加州）的小麦-玉米-休耕轮作下进行的。处理包括冬小麦收获后的三个种植时间和玉米建立前的三个 CC 终止时间和休耕（无 CC）。与晚种植相比，在冬小麦收获后不久种植 CC 增加了秋季和早春的 CC 生物量。与休耕相比，春季早期终止的覆盖作物减少了杂草生物量 (-70 %)，而春季晚期终止的覆盖作物减少了杂草密度 (-56 %) 和生物量 (-82 %)。由于试验期间降水量高于正常水平，在 0-20 cm 土壤深度测量的土壤水仅在 2016-2017 年格兰特受到 CCs 的影响。与休耕相比，在春季后期终止的覆盖作物增加了作物残留物生物量，但使 0-10 厘米土壤深度处的总氮降低了 17%，并将 10-20 厘米土壤深度处的土壤硝酸盐降低了 26%。夏末（8 月）和春末（5 月）种植的覆盖作物对玉米产量的影响最大。与休耕相比，春季 CCs 的延迟终止使玉米产量降低了 20%。尽管增强了杂草抑制和作物残留，CCs 降低了土壤氮和玉米籽粒产量，尤其是在春季后期终止时。大平原半干旱地区愿意纳入 CC 的生产者在为其 CC 选择管理策略时应谨慎行事，以尽量减少玉米产量和经济损失。CCs 降低了土壤氮和玉米的产量，尤其是在春季后期终止时。大平原半干旱地区愿意纳入 CC 的生产者在为其 CC 选择管理策略时应谨慎行事，以尽量减少玉米产量和经济损失。CCs 降低了土壤氮和玉米的产量，尤其是在春季后期终止时。大平原半干旱地区愿意纳入 CC 的生产者在为其 CC 选择管理策略时应谨慎行事，以尽量减少玉米产量和经济损失。