Tillage practices significantly influence soil nutrient retention, soil structure, and stability. However, the impact of tillage practices on soil stability and erosion resistance through the perturbation approach of soil structure remains unclear. This study aimed to establish universal principles across slope surface and soil profile scales. We evaluated the effects of various tillage practices, including conventional tillage (CT), soil compaction (CM), subsoil tillage (ST), no tillage (NT), and subsoil tillage and soil compaction (SCM) on soil stability and erosion resistance in China’s red soil hilly region. Soil stability, erosion resistance, and other soil properties were quantified using field surveys and laboratory experiments. We discovered significant variations in soil aggregate stability (SAS), wet aggregate stability (WAS), soil mechanical stability (SMS), and soil erodibility (SE) among the five tillage methods. The K factor’s average value indicated that the 0–40 cm soil layer was more erodible for CT (0.472) than for other methods, with NT (0.26) being the least erodible. NT (0.43) was the most effective treatment for reducing SE, while SCM (0.41) enhanced soil fertility, controlled SE, and mitigated machinery-induced soil compaction risks. CM (0.38) maintained soil stability without improving the soil nutrient storage, while ST (0.33) improved the soil stability such as alleviating the soil hardening caused by CM. The results provide reference parameter values for selecting appropriate tillage methods to decrease soil degradation and erosion while enhancing the soil productivity in a red soil hilly region.

Quantitative evaluations of the cultivated-layer quality (CLQ)of sloping farmland are important for the effectively improving and rationally utilizing of the cultivated layers. Using a red soil watershed as the research object, we quantitatively analysed the relationship among factors influencing the CLQ using structural equation modeling based on the DPSIR framework (A framework for describing the interactions between society and environment developed by the European Environmental Agency) to describe the CLQ evolution process. We identified the key indicators of the driving factors (D) during cultivated-layer degradation and critical environmental pressure (P) to construct a reasonable cultivatedlayer (RCL) by principal component analysis (PCA). We defined the main CLQ diagnostic indicator set to assess the CLQ by factor analysis and analysed the reasonable measures to improve the CLQ. The results show quantified direct or reverse effects among D, P, state performance (S), problem impacts (I) and response strategy (R). The contribution rates of D and P were affected by the comprehensive effects of natural and human factors or human factors along. The CLQ diagnostic indicator set included 7 soil indicators and sub-soiling is the main adjusted measure for cultivated-layer recovery. These results could provide important technological paths for objectively understanding the causes drivers of the degradation and improving the CLQ for red soil sloping farmland.