Microbial transformation of crop residue is the key process of soil organic matter (SOM) formation and mineralization, which determines soil fertility and affects global climate change. However, utilization dynamics of residue-derived carbon (residue C) by various microbial communities is still not well understood, especially under different residue quality and soil fertility conditions over a long-term scale (i.e., >1 year). In this study, a 500-day in-situ field experiment was conducted using ¹³C-labeled maize (Zea mays L.) root and shoot (composed of both stem and leaf) to examine the role of microbial community composition on the C processing. Specifically, the mineralization of residue C and incorporation of residue C into microbial biomass in low fertility (LF) and high fertility (HF) soils were investigated. The abundance of ¹³C in soil samples and microbial phospholipid fatty acids (PLFAs) were measured after 60, 90, 150 and 500 days since the residues added. The results showed that the mineralization rate of residue C was significantly higher in the LF than that in the HF soil for the first 150 days, and the shoot-derived C was more susceptible to degradation than root-derived C, but the final mineralization rates (~78%) were not significantly different among treatments on the day 500. Soil fertility significantly affected the relative composition of different microbial groups and distribution of residue C in microbial communities, but residue type did not do so. Furthermore, residue C contributed more to PLFA-C pool in the LF than HF treatments, and the proportion of root C in PLFA-C pool was higher than that of shoot C, indicating easier immobilization of root C by soil microbial anabolism. Accordingly, soil fertility and residue quality could both regulate the kinetics of the microbial immobilization of crop residue C, but overall the available residual quantity of applied (plant-derived) C to enhance or maintain soil C pool did not depend on them in a long term in the agricultural Alfisols.

作物残渣的微生物转化是土壤有机质（SOM）形成和矿化的关键过程，它决定了土壤肥力并影响全球气候变化。但是，人们对各种微生物群落的残留碳（残渣C）的利用动态仍然知之甚少，特别是在长期（即> 1年）的不同残渣质量和土壤肥力条件下。在这项研究中，使用¹³ C标记的玉米（玉米）进行了500天的现场试验L.）根和茎（由茎和叶组成）以检查微生物群落组成对碳加工的作用。具体而言，研究了低肥力（LF）和高肥力（HF）土壤中残留物C的矿化作用以及将残留物C掺入微生物生物量的情况。丰度¹³自添加残留物后60、90、150和500天后，测量土壤样品中的C和微生物磷脂脂肪酸（PLFA）。结果表明，在开始的150天里，LF中残留C的矿化率明显高于HF土壤中的残留，而芽生C比根源C更易于降解，但最终矿化率（〜78％）在第500天的处理之间无显着差异。土壤肥力显着影响不同微生物组的相对组成和微生物群落中残留物C的分布，但残留物类型却没有。此外，与HF处理相比，LF中残留物C对PLFA-C库的贡献更大，并且PLFA-C库中的根C比例高于芽C，表明土壤微生物合成代谢更容易将根C固定化。因此，土壤肥力和残渣质量都可以调节微生物对作物残渣C的固定化动力学，但是总的来说，为提高或维持土壤C库而施用（植物来源的）C的可用残渣总量并不长期取决于它们。农业中的Alfisols。