Effect of previous sloping water erosion on soil wind erosion in typical thin layered Mollisol region

Abstract: The sloping farmlands in the Mollisol region of northeast China have the characteristics of multi-agent compound soil erosion followed by snow-melt runoff erosion and then wind erosion in spring. However, the current researches on compound soil erosion in this region are still rather weak, which affects the accurate implementation of the prevention and control measures of compound soil erosion. This paper applied an approach of combining indoor simulated rainfall experiment with wind tunnel simulation experiment to analyze previous sloping water erosion effects on the soil wind erosion in the Mollisol region of northeast China. The results showed that the amount of soil wind erosion significantly reduced after the previous sloping water erosion at 50 and 100 mm/h rainfall intensities, i.e., previous sloping water erosion action produced obvious an anti-wind erosion effect. Under the action of wind speeds of 9, 12 and 15 m/s, the anti-wind erosion efficiencies produced by the previous sloping water erosion at the rainfall intensities of 50 and 100 mm/h are 68.4%-96.2% and 77.2%-97.6%, respectively; with an increase of rainfall intensity, the anti-wind erosion effect increased. The soil wind erosion rate after previous sloping water erosion action was comprehensively affected by the rainfall intensity in previous sloping water erosion and wind velocity in later soil wind erosion. With increasing of rainfall intensity, the inhibiting effect of soil wind erosion caused by previous sloping water erosion action was greater. The previous sloping water erosion action reduced wind erosion delivery and its height, and wind erosion delivery decreased with the increase of rainfall intensity of the previous sloping water erosion. The main reasons for the anti-wind erosion effect caused by the previous sloping water erosion were that the soil compaction processes caused by previous sloping rainfall and runoff altered soil physical-mechanic properties and surface morphology, which caused an increase of surface soil shear strength and soil hardness, and then enhanced soil structure stability and anti-wind erosion ability, and inhibited wind erosion occurrence. The research findings of this study not only reveal the mechanism of previous sloping water erosion affecting soil wind erosion in the Mollisol region of northeast China, but also provide a theoretical basis for preventing compound erosion and sustainably utilization of Mollisol resources.