The ongoing global change is multi‐faceted, but the interactive effects of multiple drivers on the persistence of soil carbon (C) are poorly understood. We examined the effects of warming, reactive nitrogen (N) inputs (12 g N m⁻² year⁻¹) and altered precipitation (+ or − 30% ambient) on soil aggregates and mineral‐associated C in a 4 year manipulation experiment with a semi‐arid grassland on China's Loess Plateau. Our results showed that in the absence of N inputs, precipitation additions significantly enhanced soil aggregation and promoted the coupling between aggregation and both soil fungal biomass and exchangeable Mg²⁺. However, N inputs negated the promotional effects of increased precipitation, mainly through suppressing fungal growth and altering soil pH and clay‐Mg²⁺‐OC bridging. Warming increased C content in the mineral‐associated fraction, likely by increasing inputs of root‐derived C, and reducing turnover of existing mineral‐associated C due to suppression of fungal growth and soil respiration. Together, our results provide new insights into the potential mechanisms through which multiple global change factors control soil C persistence in arid and semi‐arid grasslands. These findings suggest that the interactive effects among global change factors should be incorporated to predict the soil C dynamics under future global change scenarios.

中文翻译：

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相互作用的全球变化因素减轻了半干旱草原的土壤聚集和碳变化。

正在进行的全球变化是多方面的，但人们对多种驱动因素对土壤碳（C）持久性的相互作用的了解却很少。在一项为期4年的操作实验中，我们研究了变暖，活性氮（N）输入（12 g N m - ² 年^-1）和降水变化（+或− 30％环境）对土壤团聚体和矿物相关碳的影响，黄土高原上半干旱的草原。我们的结果表明，在没有氮素输入的情况下，添加降水显着增强了土壤的团聚并促进了团聚与土壤真菌生物量和可交换Mg ²⁺之间的耦合。。但是，氮输入主要通过抑制真菌的生长和改变土壤的pH值以及改变粘土-Mg 2 ⁺ -OC的桥接来抵消降水增加的促进作用。气候变暖可能增加了矿物相关馏分中的C含量，这可能是由于增加了根源C的投入，并由于抑制了真菌的生长和土壤呼吸而降低了现有矿物相关C的周转率。在一起，我们的结果提供了对潜在机制的新见解，通过这些潜在机制，多个全球变化因素控制了干旱和半干旱草原中土壤碳的持久性。这些发现表明，应结合全球变化因素之间的相互作用，以预测未来全球变化情景下的土壤碳动态。