The Response of the Interaction Between Soil Erosion and Tillage Layer Thickness to Environmental Variables: Evidence From the Wavy Plains of Northeastern, China

ABSTRACT There is a reciprocal interaction between soil erosion and tillage layer thickness, with the determination that a reduction in tillage layer thickness exacerbates soil erosion. However, the extent to which the degree of interaction between the two is influenced by environmental variables such as climate and topography remains insufficiently understood. This study utilized soil property data collected in 2021 and employed a random forest (RF) model in conjunction with the revised universal soil loss equation (RUSLE) to generate, for the first time, a 30 m resolution spatial distribution map of tillage layer thickness and soil erosion in the Liao He wavy plain, achieving high accuracy. The key findings are as follows: tillage layer thickness shows a spatial pattern of being thicker in the west and thinner in the east. The average soil erosion rate in the study area is 194·t·km −2 ·a −1 , with an average tillage layer loss of less than 1.9·mm·a −1 and a total erosion volume of 4.2 × 10 6 t·a −1 . Slight erosion is the dominant erosion type, whereas light erosion contributes most significantly to overall soil loss. Environmental variables have a significant influence on the interaction between soil erosion and tillage layer thickness. Specifically, increases in slope length (LS), stream power index (SPI), mean annual temperature (MAT), topographic roughness index (TRI), digital elevation mapping (DEM) and slope gradient generally enhance this interaction, whereas increases in mean annual precipitation (MAP), topographic wetness index (TWI), profile curvature (PC), catchment area (CA), normalized difference vegetation index (NDVI), and slope aspect tend to weaken it. At the local scale, a threshold effect was observed where environmental variables influence the degree of interaction between the two processes. This study offers valuable insights for mitigating regional soil erosion, contributes significantly to efforts aimed at slowing the thinning of the tillage layer thickness.