Response of soil aggregate stability and erodibility to different treatments on typical steppe in the Loess Plateau, China

Vegetation restoration is an effective means to increase the stability of aggregates and the ability of soil to resist erosion. At present, there are few studies on soil aggregate stability in contour trench and fish-scale pit grasslands (FPGs). Therefore, to determine the effects of different treatments on the stability of aggregates in the Loess Plateau, grazing grassland (GG), fencing grassland (FG), contour trench grassland (CG), and FPG were selected to compare distributions of soil aggregates, the soil aggregate stability, and soil erodibility K value. The results showed that 5-mm aggregates were the main components. The mass percentage of 5-0.25-mm aggregates in FG was significantly higher than that in GG, CG, or FPG. The proportion of large water-stable aggregates, mean weight diameter, and geometric mean diameter values were significantly higher in GG than in FG, CG, or FPG for topsoil, while FG had the highest WR0.25 (70.21%) for subsoil. The opposite trends were found for fractal dimension and percentage of aggregate destruction values. The K values for CG and FPG were found to be significantly higher than those for GG and FG. A correlation analysis indicated that soil organic carbon can promote the stability of soil aggregates. A negative correlation was found between the comprehensive score and K values. In summary, FG had positive effects on soil aggregate stability and erodibility. This finding can guide the local government to adopt enclosure measures when implementing ecological restoration of degraded grasslands.