A Laboratory Method for Predicting the Size Distribution of Sediment Eroded from Surface Soils

Abstract

AbstractA laboratory method was developed to reproduce size distributions of sediment eroded from field plots during simulated rainstorms. Using samples of surface soil from the field plots, sediment size data were generated in the laboratory by agitating soil suspensions on an orbital shaker after wetting the sample under tension. Once agitated, the samples were separated into 10 size groups ranging from >1,000 to <4 µm by wet sieve and sedimentation procedures. Size distribution curves were prepared from these data and compared with appropriate field sediment curves. Agitation times were adjusted until most points on the laboratory curves were within ±1 SD of corresponding points on the field curves. Soils high in sand and silt produced laboratory and field curves which were quite similar, but curves from soils high in clay and organic matter were less similar. Results from the 17 soils studied indicate that laboratory generated sediment size data can be used to predict size distributions of sediment eroded by simulated rainfall from interrill areas.