Forage sorghum (Sorghum bicolor (L.) Moench) is a suitable alternative for corn silage in water-limited environments due to its similar yield potential as corn but with less water input. Cover cropping could further improve forage sorghum yield and water productivity, making it the best alternative forage crop for arid and semi-arid regions. This two-year study evaluated the effect of fallow and cover crops on soil volumetric water content (VWC), soil water extraction, changes in soil water storage (∆S), seasonal crop evapotranspiration (ET_seasonal), cropping system evapotranspiration (ET_system), seasonal crop water productivity (CWP_seasonal), cropping system water productivity (CWP_system) and forage sorghum yield under a no-till semi-arid irrigated condition. Treatments included three winter cover crop mixtures: grasses + brassicas + legumes (GBL), grasses + brassicas (GB), grasses + legumes (GL), and a no-cover crop control (fallow), arranged in a randomized complete block design with four replications. Cover crops significantly reduced soil VWC at the beginning and up to 30 days after sorghum planting (DAP). However, at 60 DAP, the VWC was mostly similar among all treatments, and at 90 DAP, it was 17–21% higher under the cover crop treatments than fallow. The ET_seasonal was 22–26% higher under cover crops than fallow during cover crop growth, but it was 12–13% greater under fallow than the cover crops during forage sorghum growth. Total soil water extraction at sorghum harvest was 8–89% higher under fallow than cover crops treatments. Averaged across years, cover crop biomass yield was 11% greater with the GBL mixture than the GB and GL mixtures. Forage sorghum yield was 23%, 32%, and 18% higher under GBL, GB, and GL cover crop mixtures, respectively, than fallow. Compared to fallow, cover crop mixtures improved sorghum CWP by 38–43%. Results indicated that forage sorghum yield and CWP under semi-arid irrigated systems could be substantially improved with winter cover cropping than leaving the land fallow.

饲草高粱（Sorghum bicolor (L.) Moench）由于其与玉米相似的产量潜力，但水分输入较少，因此是在水受限环境中玉米青贮饲料的合适替代品。覆盖种植可以进一步提高牧草高粱产量和水分生产力，使其成为干旱和半干旱地区的最佳替代牧草作物。这项为期两年的研究评估了休耕和覆盖作物对土壤体积含水量（VWC）、土壤水分提取、土壤蓄水量变化（ΔS）、季节性作物蒸散（ET_季节性）、种植系统蒸散（ET _system ）的影响), 季节性作物水分生产力 (CWP_季节性), 种植系统水分生产力 (CWP _system) 和免耕半干旱灌溉条件下的草料高粱产量。处理包括三种冬季覆盖作物混合物：禾本科植物 + 芸苔属植物 + 豆科植物 (GBL)、禾本科植物 + 芸苔属植物 (GB)、禾本科植物 + 豆科植物 (GL) 和无覆盖作物对照（休耕），以随机完整区组设计与四个复制。覆盖作物在高粱种植初期和种植后 30 天（DAP）显着降低了土壤 VWC。然而，在 60 DAP 时，所有处理的 VWC 基本相似，在 90 DAP 时，覆盖作物处理比休耕处理高 17-21%。ET_季节性在覆盖作物生长期间，覆盖作物比休耕高 22-26%，但在牧草高粱生长期间，在休耕下比覆盖作物高 12-13%。高粱收获时的土壤总水分提取量比覆盖作物处理高 8-89%。多年平均，GBL 混合物的覆盖作物生物量产量比 GB 和 GL 混合物高 11%。在 GBL、GB 和 GL 覆盖作物混合物下，饲草高粱产量分别比休耕高 23%、32% 和 18%。与休耕相比，覆盖作物混合物将高粱 CWP 提高了 38-43%。结果表明，与休耕相比，冬季覆盖作物可以显着提高半干旱灌溉系统下的草料高粱产量和CWP。