Soil Physicochemical Properties and Fertility Evolution of Permanent Gully during Ecological Restoration in Granite Hilly Region of South China

Permanent gullies are a serious type of soil erosion. A special type of permanent gully, called “Benggang” severly affects agricultural production in hilly areas. To reveal the influence of Benggang erosion on granitic soil restoration and fertility, we selected three stages (active, semi-stable and stable) of Benggang recovery in the subtropical granite hilly region, and corresponding soil samples were collected to analyze the spatial variation in the soil physical and chemical qualities in the early stage of recovery. The soil physical properties and nutrients were significantly different in the runoff direction of each Benggang gully. There were significant differences in soil chemical properties and no obvious differences in physical properties among the different Benggang recovery stages. The results of principal component analysis showed that the level of soil fertility in the different Benggang recovery stages, ranked from high to low, was as follows: stable, semi-stable and active. Benggang vegetation restoration was an important factor for soil fertility restoration. Benggang ecological restoration can significantly improve the physicochemical properties and fertility of the soil. However, the soil fertility in gully erosion areas in this study still needs to be improved.