Korean Journal of Soil Science and Fertilizer ISSN:0367-6315(Print) 2288-2162(Online) 한국토양비료학회 학회지

Highland with steep slope was known a severe soil erosion area. As a result, most of the topsoil was eroded and gravels and rock fragments were exposed. It has been reported that large-sized gravel exposed to topsoil affects soil erosion caused by rainfall. The USLE also revises the K factor to surface coverage of gravel to correct the effect of the gravel content. However, it is judged that the method of Korea, which applies the existing method of applying the surface coverage of gravel as gravel contents (v/v), will be significantly different in highland with steep slope. The objective of this study was to identify how different calculation methods for determining soil erodibility factor (K) in the USLE influence the estimation of soil erosion in highland. Soils in highland as were collected by digging with an auger and a shovel, respectively. The K factor was modified by two different methods, based on surface coverage rate and content of gravel in the soil. The surface coverage of gravel was investigated at the fields via an image analysis. The K factor modified using the surface coverage rate of gravel was less than half of the K factor modified using the gravel content. And the K factor of the soils sampled by a shovel was significantly lower than that by an auger. It seemed that the soil erosion may be overestimated when the K factor was modified by the gravel contents by auger sampling. Thus, the Box’s method would be recommended that the estimation of soil erosion via the ULSE can be accurate, particularly for the gravel-rich highland soils.

Modified K factor determined with consideration of gravel contents measured by different methods.