A Multi-Indicator Assessment of Soil Erodibility in Fine-Textured Soils Under Different Land Uses

Land-use changes and unsustainable agricultural practices can alter soil properties, thereby increasing soil erodibility and the risk of land degradation. This study assessed the impact of converting forest to grassland and cropland on soil erodibility in the Kolubara watershed (western Serbia) using soil samples collected at two depths (0–15 and 15–30 cm). Soil erodibility was determined using the following indicators: clay ratio (CR), soil structure stability index (SSI), mean weight diameter (MWD), soil organic carbon cementing agent index (SCAI), saturated hydraulic conductivity (Ks), the K-factor, and a comprehensive soil erodibility index (CSEI) calculated by a weighted summation method. Most soil indicators differed significantly among land uses. Forest soils exhibited the highest MWD (2.94 mm), Ks (1119.15 mm h−1), and SSI (5.86), whereas the lowest values were recorded in cropland soils (1.64 mm, 29.68 mm h−1, and 3.07, respectively). In contrast, cropland soils showed the highest CR (0.005) and K-factor (0.038 t ha h ha−1 MJ−1 mm−1), while the lowest values occurred in forest soils (0.003 and 0.032 t ha h ha−1 MJ−1 mm−1). The significantly higher CSEI in cropland (0.75) compared with forest soils (0.62) corresponded to reduced soil structural stability and lower organic matter–related indicators. Grassland soils generally showed intermediate values for most indicators. Soil depth significantly influenced only SSI and Ks. Differences in soil erodibility among land uses are closely related to soil physical and chemical properties, particularly soil organic carbon and soil structure-related properties (total porosity and bulk density). These findings emphasize the substantial impact of land-use change on soil erodibility and highlight the need to implement effective soil conservation practices to improve soil stability and mitigate erosion.