Impact of land use type on soil erodibility in a small watershed of rolling hill northeast China

Land use type can impact soil properties and the characteristics of plant community, which in turn likely affect soil erodibility. The irrational land use induced by the fast conversion from natural forestland to cropland certainly leads to serious soil erosion. Few studies have been conducted to assess the potential effect of land use type on soil erodibility at small watershed scale. The aim of this study was to quantify the effects of six typical land use types on soil erodibility reflected by soil penetration resistance (PR), mean weigh diameter (MWD), mean number of drop impact (MND), slaking rate (SR), soil erodibility of K factor, soil organic matter content (SOM), soil structural stability index (SSI), soil cohesion (Coh), saturated hydraulic conductivity (Ks) and an integrated comprehensive soil erodibility index (CSEI) in a small watershed of rolling hill northeast China. The results revealed that MWD, MND, SOM, Coh and Ks varied significantly with land use type, with their maximum appeared in forest belt and their minimum occurred in road. The measured PR and SR exhibited an opposite trend. The calculated K factor and SSI were relatively stable or slightly fluctuating with land use type. Significant differences were found in soil texture, bulk density, root mass density and litter mass density between different land use types. CSEI varied extremely with land use type. CSEI of road was the maximum (0.855), while transverse forest belt had the minimum one (0.136). Compared to road, CSEI decreased by 14.3%, 10.8%, 26.5%, 36.9%, 33.3% and 65.7% for maize, soybean, grassland, shrub land, woodland and longitudinal forest belt, respectively. CSEI was significantly decreased and increased linearly with root mass density and bulk density. The results provide insights to understand the differences in soil erosion under different land use types in agricultural small watershed characterized by rolling hills.