Increasing the quantity and quality of plant biomass production in space and time can improve the capacity of agroecosystems to capture and store atmospheric carbon (C) in the soil. Cover cropping is a key practice to increase system net primary productivity (NPP) and increase the quantity of high‐quality plant residues available for integration into soil organic matter (SOM). Cover crop management and local environmental conditions, however, influence the magnitude of soil C stock change. Here, we used a comprehensive meta‐analysis approach to quantify the effect of cover crops on soil C stocks from the 0–30 cm soil depth in temperate climates and to identify key management and ecological factors that impact variation in this response. A total of 40 publications with 181 observations were included in the meta‐analysis representing six countries across three different continents. Overall, cover crops had a strong positive effect on soil C stocks (P < 0.0001) leading to a 12% increase, averaging 1.11 Mg C/ha more soil C relative to a no cover crop control. The strongest predictors of SOC response to cover cropping were planting and termination date (i.e., growing window), annual cover crop biomass production, and soil clay content. Cover crops planted as continuous cover or autumn planted and terminated led to 20–30% greater total soil C stocks relative to other cover crop growing windows. Likewise, high annual cover crop biomass production (>7 Mg·ha⁻¹·yr⁻¹) resulted in 30% higher total soil C stocks than lower levels of biomass production. Managing for greater NPP by improving synchronization in cover crop growing windows and climate will enhance the capacity of this practice to drawdown carbon dioxide (CO₂) from the atmosphere across agroecosystems. The integration of growing window (potentially as a proxy for biomass growth), climate, and soil factors in decision‐support tools are relevant for improving the quantification of soil C stock change under cover crops, particularly with the expansion of terrestrial soil C markets.

中文翻译：

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温带气候下覆盖作物的管理影响土壤有机碳储量：一项荟萃分析

在时空上增加植物生物量生产的数量和质量可以提高农业生态系统捕获和储存土壤中大气碳（C）的能力。覆盖作物种植是提高系统净初级生产力（NPP）和增加可用于整合到土壤有机质（SOM）中的高质量植物残渣数量的重要实践。但是，农作物的覆盖管理和当地的环境条件会影响土壤碳库变化的幅度。在这里，我们使用了一种综合的荟萃分析方法来量化在温带气候下0-30 cm土层中覆被作物对土壤碳库的影响，并确定影响这一响应变化的关键管理和生态因素。荟萃分析中总共包括40个出版物，其中有181个观测值，代表了三大洲的六个国家。总体而言，覆盖作物对土壤碳储量有很强的积极影响（P  <0.0001）导致增加12％，相对于无盖作物控制，平均土壤C增加1.11 Mg C / ha。SOC对覆盖作物响应的最强预测指标是播种和终止日期（即生长窗口），年度覆盖作物生物量产量以及土壤黏土含量。与其他覆盖作物生长期相比，以连续覆盖或秋季播种并终止播种的覆盖作物导致土壤碳总储量增加了20–30％。同样，高年覆盖作物生物量产量（> 7 Mg·ha ^-1 ·yr ^-1）导致土壤碳总储量比生物量较低的水平高出30％。通过改善覆盖作物生长窗口和气候的同步性来管理更大的NPP，将增强这种做法吸收二氧化碳的能力（CO₂）来自整个农业生态系统的大气。在决策支持工具中集成增长窗口（可能替代生物量增长），气候和土壤因素，对于改善覆盖作物下土壤碳库变化的量化尤其重要，尤其是随着陆地土壤碳市场的扩大。