Abstract: Based on sampling and analyses,the effects of returning farmland to forest on soil characteristics were investigated in Rocky Mountain, Pingguo County, Guangxi Zhuang Autonomous Region. The difference in physicochemical properties between forest land and agricultural field and the physicochemical properties of soil in typical samples under different vegetation restoration measures were analyzed. The theory ecological effect of converting farm land to forest land was estimated using price substitution method and shadow project approach. The results showed that the soil profile structure gradually improved, the soil bulk density reduced, and the total porosity, capillary porosity and water content increased after returning farmland to forest. Meanwhile, the soil organic content increased for 15% and there was no significant increase in total nitrogen content. The soil quality recovery benefit was the largest in precocious peach land and Zenia insignis land. Under different types of vegetation, the difference in soil available nutrient was larger than soil total elements. The ecological benefit values were more than 2.1 billion yuan in protection of water resource and decrease the loss of soil fertilily.

Key words: Pingguo Country, returning farmland to forest, improvement of soil, physicochemical property, ecological value