The progression of water erosion patterns from rill to gully erosion significantly affects the level of soil aggregate degradation, and thereby stimulates variations in the biochemical mechanisms controlling the OC mineralization ratio. These conditions can affect the exchange of carbon from biosphere to atmosphere. We examined the effect of erosion progression on the physical and biochemical soil properties controlling the C mineralization ratio within the original soils eroded by the rill and gully processes. Aggregate size distribution, geometric mean diameter (GMD), mean weight diameter (MWD), exchangeable cations, dissolved organic carbon (DOC), microbial respiration, and microbial biomass carbon (MBC) were measured. Despite the greater proportion of the labile components of OC in the rill soils, the C mineralization ratio exhibited lower values in these soils compared with the gully soils. A higher value of GMD, MWD, and exchangeable cations were observed in the rill soils. The results of the stepwise multiple regressions illustrated that the higher C mineralization ratio in the gully soils is significantly positively correlated with DOC and microbial respiration. By contrast, the lower C mineralization ratio in the rill soils was found to be significantly negatively related to the GMD, DOC, and MWD. These variations may be attributed to the effects of the increasing soil aggregate stability on lower vulnerability of labile organic carbon to microbial mineralization. The lower transport capacity of the rill erosion process causes a less loss of SOC and micro-aggregate compared with the gully erosion process. The labile fractions of SOC could bond with clay fractions and exchangeable cations to contribute toward the formation of soil aggregates, encouraging higher resistance of DOC against microbial mineralization in the rill soils. This conceptual approach of combining our field survey data with an empirical model aids in a better understanding of the biochemical mechanisms controlling the C mineralization ratio under the progression of soil erosion.

从细沟侵蚀到沟侵蚀的水侵蚀模式的进展显着影响土壤团聚体退化的水平，从而刺激控制OC矿化率的生化机制的变化。这些条件会影响碳从生物圈到大气的交换。我们检查了侵蚀进程对控制被细沟和沟壑过程侵蚀的原始土壤中的碳矿化率的物理和生化土壤性质的影响。测量了聚集体尺寸分布、几何平均直径 (GMD)、平均重量直径 (MWD)、可交换阳离子、溶解有机碳 (DOC)、微生物呼吸和微生物生物量碳 (MBC)。尽管小沟土壤中 OC 不稳定成分的比例较大，与沟壑土相比，这些土壤的碳矿化率较低。在细沟土壤中观察到较高的 GMD、MWD 和可交换阳离子值。逐步多元回归的结果表明，沟壑土壤中较高的C矿化率与DOC和微生物呼吸显着正相关。相比之下，发现细沟土壤中较低的 C 矿化率与 GMD、DOC 和 MWD 显着负相关。这些变化可能归因于土壤团聚体稳定性的增加对不稳定有机碳对微生物矿化的脆弱性降低的影响。与沟壑侵蚀过程相比，细沟侵蚀过程的较低输送能力导致土壤有机碳和微团聚体的损失较少。SOC 的不稳定部分可以与粘土部分和可交换的阳离子结合以促进土壤团聚体的形成，从而提高 DOC 对小沟土壤中微生物矿化的抵抗力。这种将我们的实地调查数据与经验模型相结合的概念方法有助于更好地理解在土壤侵蚀过程中控制 C 矿化率的生化机制。