Abstract. The objectives of this work were to select the possible best texture-based method to estimate K and understand possible indirect environmental factors of soil erodibility. In this study, 151 soil samples were collected during soil surveys in Ansai watershed. Five methods of estimating K value were used to estimate soil erodibility, including the erosion-productivity impact model (EPIC), the nomograph equation (NOMO), the modified nomograph equation (M-NOMO), the Torri model and the Shirazi model. The K values in Ansai watershed ranged between 0.009 and 0.092 t hm2 hr/(MJ mm hm2). The K values based on Torri, NOMO, and Shirazi models were similar and were located close to each other in the Taylor diagrams. By combining the measured soil erodibility, we suggested Shirazi and Torri model as the optimal models for Ansai watershed. The correlations between soil erodibility and the selected environmental variables changed for different vegetation type. For native grasslands, soil erodibility had significant correlations with terrain factors. For most artificially managed vegetation types (e.g., apple orchards) and artificially restored vegetation types (e.g., sea buckthorn), the soil erodibility had significant correlations with the growing conditions of vegetation. The dominant factors that influenced soil erodibility differed with different vegetation types. Soil erodibility had indirect relationship with not only environmental factors (e.g., elevation and slope), but also human activities which potentially altered soil erodibility.
Soil erodibility estimation by using five methods of estimating <i>K</i> value: A case study in Ansai watershed of Loess Plateau, China