Organic amendments stimulate carbon (C) mineralization by affecting the soil nutrient content, soil organic carbon (SOC) chemistry, and microbial community structure, especially keystone taxa. Exogenous substrates' quality is expected to affect the relative importance of these biotic and abiotic factors in C mineralization. However, little evidence from long-term studies has been found, and the underlying mechanisms remain unclear. Therefore, this study investigated how exogenous substrate quality affects the changes in keystone taxa and their relative contribution to C mineralization in comparison with soil nutrient content and SOC chemistry in a long-term field experiment. Six fertilization treatments from a 30-year field experiment were selected. To investigate the impact of substrate quality, the six treatments were sorted into three groups: non-organic-amended group, including no fertilization and inorganic N fertilizer; green manure-amended groups, including full amount of green manure input and 50% green manure plus 50% inorganic N fertilizer; and wheat straw-amended group, including full amount of wheat straw input and 50% wheat straw plus 50% inorganic N fertilizer. Our results confirmed that the relative importance of keystone taxa on C mineralization varied according to the exogenous substrates’ quality. In the non-organic-amended group, the keystone taxa belonged to Betaproteobacteriales, and the keystone Betaproteobacteriales module, from guided network analysis, was associated with higher C mineralization. In the wheat straw-amended treatments, the keystone taxa Chaetomiaceae module had a dominant influence on C mineralization. In contrast, in the green manure-amended treatments, the keystone taxa in Subgroups 4 and 6 of Acidobacteria and Alphaproteobacteria had a limited impact on the C mineralization rate, whereas the increased aromatic C component was an important explanatory variable associated with C mineralization. In conclusion, this study confirmed that exogenous organic substrate quality affects the occurrence of keystone microbial taxa linked to soil C mineralization.

有机改良剂通过影响土壤养分含量、土壤有机碳 (SOC) 化学和微生物群落结构，尤其是关键类群来刺激碳 (C) 矿化。预计外源底物的质量会影响这些生物和非生物因素在 C 矿化中的相对重要性。然而，长期研究的证据很少，其潜在机制仍不清楚。因此，本研究通过长期田间试验研究了与土壤养分含量和 SOC 化学相比，外源基质质量如何影响关键类群的变化及其对 C 矿化的相对贡献。选择了来自 30 年田间试验的六个施肥处理。为了研究基板质量的影响，六个处理分为三组：非有机改良组，包括不施肥和无机氮肥；绿肥改良组，包括全量绿肥投入和50%绿肥加50%无机氮肥；麦秆改良组，包括全量麦秆投入和50%麦秆加50%无机氮肥。我们的研究结果证实，关键类群对 C 矿化的相对重要性根据外源基质的质量而变化。在非有机修正组中，基石类群属于 包括全量麦秸投入和50%麦秸加50%无机氮肥。我们的研究结果证实，关键类群对 C 矿化的相对重要性根据外源基质的质量而变化。在非有机修正组中，基石类群属于 包括全量麦秸投入和50%麦秸加50%无机氮肥。我们的研究结果证实，关键类群对 C 矿化的相对重要性根据外源基质的质量而变化。在非有机修正组中，基石类群属于来自引导网络分析的Betaproteobacteriales和关键Betaproteobacteriales模块与较高的 C 矿化有关。在小麦秸秆改良处理中，基石类群Chaetomiaceae模块对 C 矿化具有显着影响。相比之下，在绿肥改良处理中，Acidobacteria 和 Alphaproteobacteria 亚组 4 和 6 中的关键类群对C矿化速率的影响有限，而增加的芳香 C 组分是与 C 矿化相关的重要解释变量。总之，本研究证实外源有机基质质量影响与土壤碳矿化相关的关键微生物类群的发生。