Including cover crops within agricultural rotations may increase soil organic carbon (SOC). However, contradictory findings generated by on-site experiments make it necessary to perform a comprehensive assessment of interactions between cover crops, environmental and management factors, and changes in SOC. In this study, we collected data from studies that compared agricultural production with and without cover crops, and then analyzed those data using meta-analysis and regression. Our results showed that including cover crops into rotations significantly increased SOC, with an overall mean change of 15.5% (95% confidence interval of 13.8%–17.3%). Whereas medium-textured soils had highest SOC stocks (overall means of 39 Mg ha⁻¹ with and 37 Mg ha⁻¹ without cover crops), fine-textured soils showed the greatest increase in SOC after the inclusion of cover crops (mean change of 39.5%). Coarse-textured (11.4%) and medium-textured soils (10.3%) had comparatively smaller changes in SOC, while soils in temperate climates had greater changes (18.7%) than those in tropical climates (7.2%). Cover crop mixtures resulted in greater increases in SOC compared to mono-species cover crops, and using legumes caused greater SOC increases than grass species. Cover crop biomass positively affected SOC changes while carbon:nitrogen ratio of cover crop biomass was negatively correlated with SOC changes. Cover cropping was associated with significant SOC increases in shallow soils (≤30 cm), but not in subsurface soils (>30 cm). The regression analysis revealed that SOC changes from cover cropping correlated with improvements in soil quality, specifically decreased runoff and erosion and increased mineralizable carbon, mineralizable nitrogen, and soil nitrogen. Soil carbon change was also affected by annual temperature, number of years after start of cover crop usage, latitude, and initial SOC concentrations. Finally, the mean rate of carbon sequestration from cover cropping across all studies was 0.56 Mg ha⁻¹ yr⁻¹. If 15% of current global cropland were to adopt cover crops, this value would translate to 0.16 ± 0.06 Pg of carbon sequestered per year, which is ~1–2% of current fossil fuels emissions. Altogether, these results indicated that the inclusion of cover crops into agricultural rotations can enhance soil carbon concentrations, improve many soil quality parameters, and serve as a potential sink for atmosphere CO₂.

将轮作作物包括在农业轮作中可能会增加土壤有机碳（SOC）。但是，现场实验产生的矛盾结果使得有必要对覆盖作物，环境和管理因素以及有机碳变化之间的相互作用进行全面评估。在这项研究中，我们从比较有盖作物和无盖作物的农业生产的研究中收集了数据，然后使用荟萃分析和回归分析了这些数据。我们的结果表明，将轮作作物包括轮作后，SOC显着提高，总体平均变化为15.5％（95％的置信区间为13.8％-17.3％）。中等质地土壤的SOC含量最高（总体平均值为39 Mg ha ^-1和37 Mg ha ^-1在没有覆盖作物的情况下，质地细密的土壤在加入覆盖作物后表现出最大的SOC增加（平均变化为39.5％）。质地较粗的土壤（11.4％）和中等质地的土壤（10.3％）的SOC变化相对较小，而温带气候下的土壤变化较大（18.7％），而热带气候下的土壤变化为7.2％。与单一物种的覆盖作物相比，覆盖作物混合物导致SOC的增加更大，并且使用豆类导致的SOC增加比草种更大。覆盖作物生物量对SOC变化有正向影响，而覆盖作物生物量的碳氮比与SOC变化呈负相关。覆盖作物与浅层土壤（≤30cm）中的SOC显着增加相关，而地下土壤（> 30 cm）中却没有。回归分析表明，覆盖耕作的土壤有机碳变化与土壤质量的改善相关，特别是径流和侵蚀的减少以及可矿化碳，可矿化氮和土壤氮的增加。土壤碳变化还受到年度温度，覆盖作物开始使用后的年数，纬度和初始SOC浓度的影响。最后，在所有研究中，覆盖作物的固碳速度平均为0.56 Mg ha^-1年- ^1年。如果目前全球15％的农田要采用掩盖作物，那么该值将转化为每年固存的0.16±0.06 Pg碳，约占当前化石燃料排放量的1-2％。总之，这些结果表明将轮作作物包括在农业轮作中可以提高土壤碳含量，改善许多土壤质量参数，并可能成为大气CO ₂的潜在汇。