Response mechanism of black soil structure to compound erosion forces in sloping farmland, Northeast China

Compound erosive forces lead to the deterioration of black soil structure and thus increase soil erosion. However, the successive temporal characteristics of different erosive forces and the response mechanisms of black soil properties to them remain unclear. In the Nenjiang area, we collected meteorological data from 1990 to 2020 and data from local agricultural activities over the past ten years. We also monitored the in situ soil structure of sloping farmland in the black soil region for one year. The purpose of this study was to clarify the mechanisms controlling the soil structure response and erosion resistance under the seasonal alternating effects of compound erosive forces. The results showed that five compound erosive forces occurred sequentially on an intra-annual scale. The combined effects of water and intertillage resulted in a significant (p < 0.05) decrease in soil bulk density (BD) and aggregate stability. The BD and mean weight diameter (MWD) reached their lowest values of the stage after fall tillage. Aggregate stability decreased significantly under the first freezethaw and snowmelt period action and gradually recovered after. The percentage of aggregates with DR < 0.84 was significantly reduced by 21.22% after wind-sowing action. Soil aggregate fragmentation significantly increased K (p < 0.001, R2=0.726), and BD had a greater correlation with Coh (p < 0.01, R2=0.429). Intertillage, harrowing, and sowing are the primary factors that influence the response of soil structure and erosion resistance during various stages. The results of this study can provide theoretical references for understanding the process of compound erosion processes and optimizing agricultural practices.