ABSTRACT

Unraveling the influence of microbes on C content at aggregate scale is pivotal for promoting soil C accumulation. Previous studies were based mainly on the mutual transformation process between aggregates, the links between the microorganisms in initial aggregates and inner C content and aggregate sizes were still unclear. In this study, the classified aggregates (> 5 mm, 2–5 mm, 1–2 mm, 0.25–1 mm, and < 0.25 mm) were individually incubated for 10 months under ¹³C-labeled maize straw application to analyze the relationship between microbial community structure in independent aggregates and inner C accumulation under straw addition. The results show that the SOC content increased in independent aggregates under straw addition, with higher stable C accumulation in < 0.25 mm than in > 2 mm aggregates. Aggregates of > 5 mm were more capable of improving unstable C accumulation and C derived from straw (C_straw) than smaller aggregates. Fungi and Gram-negative bacteria (G-) were more important to increasing C accumulation in > 2 mm aggregates, whereas Gram-positive (G+) bacteria dominated in < 2 mm aggregates. The results indicate that the contribution of microorganisms within aggregates to inner C accumulation was associated with aggregate sizes.

摘要

揭示微生物对团聚体 C 含量的影响对于促进土壤 C 积累至关重要。以往的研究主要基于团聚体之间的相互转化过程，初始团聚体中的微生物与内部C含量和团聚体大小之间的联系尚不清楚。^{在这项研究中，分类的聚集体（> 5 毫米、2-5 毫米、1-2 毫米、0.25-1 毫米和 < 0.25 毫米）在13}岁以下单独孵育 10 个月应用 C 标记的玉米秸秆分析独立团聚体中微生物群落结构与秸秆添加下内部 C 积累之间的关系。结果表明，添加秸秆后独立团聚体的 SOC 含量增加，< 0.25 mm 团聚体的稳定 C 积累高于 > 2 mm 团聚体。> 5 mm 的聚集体比较小的聚集体更有能力改善不稳定的 C 积累和来自秸秆的 C（C _straw）。真菌和革兰氏阴性菌 (G-) 对于增加 > 2 mm 聚集体中的碳积累更为重要，而革兰氏阳性 (G+) 细菌在 < 2 mm 聚集体中占主导地位。结果表明，聚集体中的微生物对内部 C 积累的贡献与聚集体大小相关。