A laboratory study of the erodibilities of four agriculturally productive soils

Soil erosion by water is a serious problem throughout the world. It has been studied for most of this century, but much remains unknown and mis\mderstood. A study was conducted at The University of Tennessee to investigate relationships among soil properties and their possible uses as indicators of erodibility. Soil losses from four agriculturally productive East Tennessee soils were investigated under simulated rainfall. The effects of soil moisture, particle size distribution, organic matter, and other soil properties were studied, along with the effect of storm intensity. The largest difference between expected and observed erodibilities appeared to be due to the effect of a strong structure in a finer-textured (clay loam) soil. Subangular blocky structure was not expected to correspond to low erodibility. However, when the permeability of the underlying soil is sufficient and the aggregates are water stable, most of the water that strikes the surface enters the soil rather than becoming soil-carrying runoff. The findings of the study indicated that intensity and antecedent moisture do not affect all soils equally. Soil-loss tests used to compute a general erodibility value for a particular soil must include as much of a range of conditions as can be expected for that soil. The resulting value will be a good average, but probably a poor predictor for specific cases. Additional work is needed to be able to accurately predict soil loss from a particular site induced by a specific storm.