Regulatory Effects of Soil and Water Conservation Practices on Hydrological Processes in the Red Soil Zone of Southern China Driven by Time‐Course Rainfall

Rainfall depth fluctuates, which increases the uncertainty of soil erosion and moisture dynamics in sloping cropland. Soil and water conservation practices affect soil erosion and moisture infiltration. However, the responses of runoff and soil moisture to time‐course rainfall patterns under soil and water conservation practices are not fully understood. Based on the distribution of concentrated rainfall depth, we classified 122 natural rainfall events in Southern China from 2019 to 2022 into advanced, intermediate, delayed, and uniform patterns. We used 12 runoff plots to observe runoff and soil moisture dynamics in sloping cropland under soil and water conservation practices (i.e., bare land, no‐till, conventional tillage, conventional tillage with straw mulch, conventional tillage with polyacrylamide, and cross‐slope ridge tillage). The results demonstrate that the advanced and intermediate rainfall patterns were the most prevalent in South China, occurring up to 82.79% of the frequency and contributing to 88.27% of the total runoff depth. Soil moisture increment and growth rate were maximum for the advanced pattern and minimum for the uniform pattern, and decreased with increasing soil depth, but soil moisture increment per unit of rainfall depth was maximum for the delayed pattern. Soil moisture increment and pre‐rainfall soil moisture content were negatively correlated under advanced, intermediate, and delayed patterns but were positively correlated under the uniform pattern. Additionally, the applied soil and water conservation practices reduced annual runoff depth by 69%–79% and significantly increased long‐term soil moisture content. The combined effect of the practices on runoff and soil moisture indicates that ploughing in conjunction with straw mulching is a more suitable practice for sloping land in Southern China. The findings can enhance our comprehension of runoff generation and soil moisture infiltration processes in red soil hilly regions and furnish guidance for improving regional soil and water conservation strategies.