Cover crops are an important component of sustainable agriculture, and additional carbon (C) source inputs can accelerate the soil C cycle. However, the specific processes and factors that control cover crop impact on soil organic carbon (SOC) mineralization are still uncertain. In this study, the ecological associations among SOC fractions, soil bacterial composition, microbial metabolic potential, and soil metabolites and their combination with SOC mineralization based on an eight-year cover crop field experiment (summer fallow–winter wheat (Fallow), buckwheat–winter wheat (Buckwheat), black bean–winter wheat (Black bean) and sorghum sudangrass–winter wheat (Grass)) were analyzed. The results showed that cover crops increased SOC mineralization, which was 10.61 mg CO-C kg soil d for Fallow and 1.17, 1.20 and 1.34 times greater for Buckwheat, Black bean and Grass, respectively, and that the SOC fractions and microbial metabolic potential showed similar trends to those of SOC mineralization. Cover crops increased the labile C content and amino acid and carboxylic acid metabolic activity, altered the soil bacterial composition and increased the amount of differentially abundant metabolites (DAMs). Hierarchical analyses revealed that soil bacteria and metabolites explained the majority of the variation in SOC mineralization, and partial least squares path modeling (PLS-PM) further revealed that soil bacteria increase microbial metabolic activity by regulating metabolites to promote SOC mineralization. Thus, cover crops alter the soil bacterial composition and stimulate microbial catabolic activity to influence the SOC cycle, a process in which soil metabolites play a key role.

中文翻译：

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对有机碳矿化的新见解：结合土壤有机碳组分、土壤细菌组成、微生物代谢潜力和土壤代谢物


覆盖作物是可持续农业的重要组成部分，额外的碳 (C) 源投入可以加速土壤碳循环。然而，控制覆盖作物对土壤有机碳（SOC）矿化影响的具体过程和因素仍不确定。在这项研究中，基于八年的覆盖作物田间试验（夏季休耕-冬小麦（休耕）、荞麦-分析了冬小麦（Buckwheat）、黑豆-冬小麦（Black bean）和高粱苏丹草-冬小麦（Grass））。结果表明，覆盖作物增加了 SOC 矿化，休耕为 10.61 mg CO-C kg 土壤·d，荞麦、黑豆和草分别为 1.17、1.20 和 1.34 倍，并且 SOC 分数和微生物代谢潜力显示与 SOC 矿化趋势相似。覆盖作物增加了不稳定碳含量以及氨基酸和羧酸代谢活性，改变了土壤细菌组成并增加了差异丰度代谢物（DAM）的数量。层次分析表明土壤细菌和代谢物解释了SOC矿化的大部分变化，偏最小二乘路径模型（PLS-PM）进一步揭示土壤细菌通过调节代谢物来促进SOC矿化，从而增加微生物代谢活动。因此，覆盖作物改变土壤细菌组成并刺激微生物分解代谢活动，从而影响 SOC 循环，而土壤代谢物在这一过程中发挥着关键作用。