A study of relative erodibility of a group of Mississippi gully soils

Abstract

In attempting to correlate watershed characteristics with reservoir sediment in a 1951 study, unexplained variation was found. It was thought that basic differences in soil erodibility between watersheds might account for a part of this variation. Accordingly studies were made to determine erodibility difference between soils, using several methods and using gully soils, free of vegetative influences. No absolute measure of erodibility seemed available. A laboratory rainmaker was used on cores of undisturbed soil and compared with a wet sieving aggregate stability method on pulverized soil Both were contrasted with natural rain splash losses on 9‐inch diameter cores of undisturbed soil.Soil losses by laboratory splash technique generally compared very well with results by the aggregate stability method. The results from these two methods did not compare well with splash erosion caused by 29 months of actual rain except from the sandy material. The high percentage of natural rain at intensities below the critical value for detaching cemented soils was thought responsible.It appears that soils vary widely in their resistance to erosion as determined by any method. It further appears that relative erodibility may be varied depending upon the choice of methods of applying the erosion producing energy. Although no generally accepted standard method of assessing erodibility is yet available it is encouraging that different soils show widely different erosion rates. Therefore there is a possibility of deriving a method adequate to express erosion susceptibility differences. Loose sandy material from different geologic sources had about the same erosion potential regardless of method of evaluation. In general splash erosion increased with increase in sand content of the soil material. Aggregate stability decreased with increasing sand content.