Variation in soil erodibility under five typical land uses in a small watershed on the Loess Plateau, China

Abstract

The adjustment of land use can alter the near soil surface characteristics and thus likely affects soil erodibility. However, few studies have been carried out to assess the variations in soil erodibility under different land uses on the Loess Plateau after many slope farmlands have been converted to green lands in the past several decades. This study was conducted to quantify comprehensively the effects of five typical land uses (cropland, orchard, grassland, shrubland and woodland) on soil erodibility based on soil cohesion (Coh), saturated conductivity (Ks), the number of drop impact (NDI), the mean weight diameter of soil aggregates (MWD), soil penetration resistance (PR) and soil erodibility K factor from different aspects, as well as a comprehensive soil erodibility index (CSEI) produced by a weighted summation method. The results showed that Coh of grassland, Ks of woodland, and MWD and NDI of shrubland were the maximum, while PR of woodland and K of shrubland were the minimum among five tested land uses. Soil erodibility (reflected by CSEI) of shrubland was the minimum, while cropland had the maximum CSEI. Compared to cropland, soil erodibility decreased by 15.5%, 53.0%, 77.2% and 59.6% for orchard, grassland, shrubland and woodland, respectively. The variation in soil erodibility under different land uses was closely related to near soil surface characteristics. Soil erodibility increased with soil bulk density, and decreased with biological soil crust thickness, organic matter content, plant litter density, and root density. The results are helpful for optimizing spatial planning and improving eco-environment on the Loess Plateau.