Characterization of Rill and Interrill Eroded Soil

THREE soils were subjected to simulated rainfall to induce runoff and soil loss from 1.52- by 4.52-m laboratory plots with preformed rills. Soil loss was separated into that originating in the rill and interrill areas. The relative amounts of rill- and interrill-eroded soil were related to soil aggregation, aggregate stability, soil organic matter content, and particle-size distri-bution. Soil with a high degree of aggregation and relatively water-stable aggregates was less susceptible to interrill erosion (erosion by raindrop) than was more poorly aggregated soil. However, soil low in organic matter was much more susceptible to rill erosion (erosion from flowing water). Also, the degree of slope tended to affect the source of the eroded material with the interrill areas providing an increasingly larger per-centage of the total soil loss as the degree of slope increased.