Replacing summer-fallow by growing cover crops (CC) in semi-arid regions might provide several soil health benefits. This study examined the effects of long-term CC management in place of fallow on soil properties in a no-till (NT) winter wheat (Triticum aestivum L.)-grain sorghum (Sorghum bicolor Moench)-fallow (WSF) cropping system. Fallow replacement treatments were spring-planted and included peas (Pisum sativum L.) for grain as well as one-, three-, and six-species CC mixtures compared with summer-fallow. Half of each CC treatment was harvested for forage and the other half remained standing after termination. Soil organic carbon (SOC) stocks within the 0- to 15-cm soil depth increased by 0.14 Mg ha^-1 yr^-1 for each Mg ha^-1 CC residue added from 2008 to 2012 and were unaffected by CC diversity. However, SOC stocks were not different than fallow in 2018 likely because CC residue inputs declined due to a succession of drought years. Residue contribution from grain sorghum in the WSF rotation best predicted SOC in 2018 compared to 2012. Soil aggregation was greater with CCs compared to peas or fallow and was unaffected by CC diversity. Mean weight diameter (MWD) of water stable aggregates in 2018 was greater with standing CCs (1.11 mm) compared to peas (0.77 mm) but was similar to fallow (0.84 mm). The MWD of dry aggregates with standing (3.55 mm) and hayed (3.62 mm) CCs were greater compared to fallow (2.75 mm). Our findings suggest simple CC mixtures and CCs managed for hay provide similar soil benefits as diverse CC mixtures or CCs left standing in this semi-arid environment.

通过在半干旱地区种植覆盖作物 (CC) 来代替夏季休耕可能会带来多种土壤健康益处。本研究在免耕 (NT) 冬小麦 ( Triticum aestivum L.)-高粱 ( Sorghum bicolor Moench)-休耕 (WSF) 种植系统中研究了长期 CC 管理代替休耕对土壤特性的影响。与夏季休耕相比，春季种植休耕替代处理，包括用于谷物的豌豆 ( Pisum sativum L.) 以及一种、三种和六种 CC 混合物。每个CC处理的一半被收获作为草料，另一半在终止后保持站立。0 至 15 cm 土壤深度内的土壤有机碳 (SOC) 储量增加了 0.14 Mg ha ^-1 yr ^-1每 Mg ha ^-12008 年至 2012 年添加的 CC 残基不受 CC 多样性的影响。然而，SOC 库存与 2018 年的休耕并无不同，可能是因为连续干旱年份导致 CC 残留物投入下降。与 2012 年相比，在 WSF 轮作中谷物高粱的残留贡献最好地预测了 2018 年的 SOC。与豌豆或休耕相比，CCs 的土壤聚集更大，并且不受 CC 多样性的影响。与豌豆（0.77 毫米）相比，2018 年水稳聚集体的平均重量直径（MWD）与豌豆（0.77 毫米）相比，立式 CC（1.11 毫米）更大，但与休耕（0.84 毫米）相似。与休耕 (2.75 mm) 相比，具有站立 (3.55 mm) 和干草 (3.62 mm) CCs 的干骨料的 MWD 更大。