Experimental analysis of erosion mechanisms: superficial structural degradation and detachment of particles from cultivated soils

Abstract

Crusting and erosion of cultivated soils result from aggregate breakdown and the detachment of soil fragments by rain, and the susceptibility of soil to these processes can be inferred from measurements of aggregate stability. Here, four main mechanisms (i.e. slaking, breakdown by differential swelling, mechanical breakdown by raindrop impact and physico-chemical dispersion) are defined. Their relative importance depends on the nature of the rain, as well as on the soilts physical and chemical properties. The relations between aggregate breakdown, crusting and water erosion were analysed. The effect of crust spatial variability and initial moisture content on infiltration and runoff are presented. The influence of slope steepness on runoff and erosion for a crusted interrill area and the detachment and transport processes involved in the interaction between slope, rain characteristics and plot size are also investigated.