Nitrogen and phosphorus transfer under intensive agricultural production in eastern China

Agriculture is an important contributor to non-point source pollution in the water environment system. The exact transfer of nitrogen and phosphorus in an agriculturally dominated area is still poorly understood. The pollutant export shows a high spatial and temporal variation and the relevant factors are complex and nonlinear in nature. There is a dramatic increase of synthetic fertilizer usage in southern China in recent decade due to decreasing farmland and increasing food demand. Massive N and P fertilizer application has led to many environmental problems, especially eutophication. The objective of this research is to study the agricultural diffuse pollution transfer on the watershed scale and field scale through event-based, on-site observation and sampling. In the study area, Meilin Watershed, nutrients are more likely to be loss with surface runoff during high intensity rainfall events, phosphorus in particular. The influential factors for N and P transfer are generalized as hydrology, cultivation management and soil. Based on detailed field experiments, the N and P transfer in different seasons, runoff components, land covers and tillage practices is elucidated. Furthermore, the spatial and temporal heterogeneity of pollutant movement processes is delineated.