Risk simplified assessment on phosphorus loss risk based on digital soil system at county scale

County is the basic administrative unit in China. This paper explored a simplified method of soil phosphorus loss risk assessment at county scale in order to provide guidance for the county phosphorus risk assessment and production practices. Under considering the characteristics of the county scale, the paper simplified phosphorus index assessment method, and assessed phosphorus loss risk for Shunyi district based on digital soil system using GIS technology and pedometrics. The research results showed that the phosphorus loss in the study area presents higher level in the east and lower in the west, and zonal distribution along the rivers. The distribution pattern mainly was led by agricultural inputs. Risk of soil phosphorus loss was overall lower in the study area, but the moderate risk accounted for 30.05% of the total area. Phosphorus management should be strengthened and soil phosphorus loss should be prevented in the future. The simplified P index-based digital soil could reflect risk level of regional phosphorus loss, which can provide risk a reference for risk assessment for the county phosphorus loss.