Soil Infiltration Capability of Project of Removal Lands From Cultivation for Afforestation and Grass planting in Beichuanhe Watershed

Infiltration is not only the important physical capability of soil but also the main part of the ecological benefits. The study on the mechanism of soil infiltration of the Project of Removal Lands from Cultivation for Afforestation and Grass planting (PRLCAG) could provide scientific bases for the project development favorably. Infiltration tests are carried out with the method of Double Test Rings in Beichuanhe Watershed of Datong County, Qinghai Province, one of the national experimental counties for PRLCAG. The results showed that the infiltration processes for epipedon of the rehabilitation lands have high rates at the beginning, medium rates at the mid periods, and lower rates at the ending time which are nearly unchangeable and trend to be constants, the whole process can be imitated well with Inverse and S models. With an average final infiltration rate of 4.2mm/min, the epipedon of rehabilitation land has the same final infiltration function compared with natural forest land, and which is 9.5 times higher than that of cropland. The final infiltration capability can be gradually and effectively improved with the increase of branches and leaves growth of forest, accumulation of litter, thickening of epipedon and soil melioration along with the normal growth of the artificial forests in the rehabilitation lands.