Increasing agroecosystem biodiversity with cover crops can restore many ecosystem functions that are lost with simplified crop rotations. Mixtures of species with complementary plant traits, such as legumes and grasses, may increase multiple functions at once, including soil nutrient supply and retention, which depend on microbial decomposition dynamics. Litter mixtures can stimulate decomposition compared to individual species, and decomposition also varies with soil properties. However, the interactive effect of cover crop functional type and soil fertility status on decomposition are not known. Here, we tested for mixture effects with a legume–grass litter in soils with lower and higher levels of fertility. We also identified specific soil properties that are associated with those effects. We incubated hairy vetch, cereal rye, and vetch‐rye litter treatments for 360 d in two soils from fields with contrasting management histories and fertility levels, as defined by biological indicators such as particulate organic matter (POM) pools. We measured decomposition dynamics through respired CO₂, microbial biomass, microbial extracellular enzyme activity, and inorganic nitrogen (N) mineralization. With no litter addition, the soil with larger POM pools had twofold greater microbial biomass C, seven times more net N mineralization, and respired 58% more CO₂. Across both soils, after 30 d microbial biomass C increased by 58–208% following litter addition, and litter addition significantly increased CO₂ production compared to the no‐litter control. However, there was no difference in the magnitude of CO₂ production among cover crop treatments and soils after litter addition. The lower fertility soil had a greater response to the litter C input for CO₂ production and enzyme activities in soil. Furthermore, the size and N content of free and intra‐aggregate POM pools were associated with differences in the microbial response to litter addition. Our results demonstrate that cover crop litter affects microbial decomposition dynamics differently in soils with distinct soil fertility levels and suggests that new C inputs have larger effects in lower fertility soils. Understanding how soils with different fertility levels respond to diverse cover crops, including mixtures, will inform management of agroecosystems for sustainability.

中文翻译：

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土壤肥力状态控制垃圾混合物残留物的分解

覆盖作物增加了农业生态系统的生物多样性，可以恢复许多由于简化轮作而丧失的生态系统功能。具有互补植物性状的物种混合物（例如豆类和草）可能会同时增加多种功能，包括土壤养分的供应和保留，这取决于微生物的分解动力学。与单个物种相比，垃圾混合物可以刺激分解，分解也随土壤特性而变化。但是，覆盖作物功能类型和土壤肥力状况对分解的交互作用尚不清楚。在这里，我们测试了在肥力水平较低和较高的土壤中，用豆科植物的草屑混合的效果。我们还确定了与这些影响相关的特定土壤特性。我们孵化了毛v子，谷物黑麦，在两种土壤中进行了360 d的紫菜和黑麦草凋落物处理，其管理历史和肥力水平存在差异，这由生物指标（如颗粒有机物（POM）池）定义。我们通过呼吸的一氧化碳测量了分解动力学₂，微生物生物量，微生物细胞外酶活性和无机氮（N）矿化。如果不添加垃圾，则具有较大POM池的土壤中的微生物生物量C会增加两倍，净氮矿化量增加七倍，而呼吸的CO _2则增加58％。在两种土壤中，添加无垫料后30 d后，微生物量C增加了58–208％，与无垫料对照相比，添加垫料显着增加了CO _2的产生。然而，在覆盖作物处理和添加凋落物的土壤之间，CO ₂产生的量没有差异。肥力较低的土壤对垫料CO输入CO _2的响应更大。土壤中的生产和酶活性。此外，游离和聚集体内POM库的大小和N含量与微生物对垫料添加的反应差异有关。我们的结果表明，在土壤肥力水平不同的情况下，农作物凋落物对微生物分解动力学的影响不同，并表明在低肥力土壤中新的碳输入对土壤微生物分解的影响更大。了解不同肥力水平的土壤如何应对包括覆盖物在内的多种覆盖作物，将为农业生态系统的可持续管理提供信息。