Towards mapping large scale soil erodibility by using pedological knowledge

Soil erodibility is a key parameter to measure soil susceptibility to water erosion and thus to soil erosion modelling, introduced as K factor in the Universal Soil Loss Equation (USLE) and the Revised Universal Soil Loss Equation (RUSLE). However, subject to soil spatial heterogeneity and data availability, large-scale K value acquisition has not been properly addressed. In this study, authors aimed to construct a new large-scale soil erodibility mapping technique to provide methodological support for regional soil erosion surveys. Taking the mountainous Yunnan province as a case, 743 soil samples from 252 typical soil series were collected. A 'GIS-based pedological method' was developed to construct a large-scale soil erodibility database by linking a soil map with soil properties. K value in Yunnan varied between 0.0004 and 0.0169 t ha h ha(-1) MJ(-1) mm(-1), with an average of 0.0065 t ha h ha(-1) MJ(-1) mm(-1). Significantly different K values were found among different types of soils and land use (p < 0.05). Redundancy analysis indicated that annual average temperature and latitude were the dominant control factors. The study showed that regional K value estimated by 'GIS-based pedological method' manifested an improvement compared to the traditional spatial interpolation method.