An Integrated Quantitative Method to Simultaneously Monitor Soil Erosion and Non-Point Source Pollution in an Intensive Agricultural Area

In China, some areas with intensive agricultural use are facing serious environmental problems caused by non-point source pollution (NPSP) as a consequence of soil erosion (SE). Until now, simultaneous monitoring of both NPSP and SE is difficult due to the intertwined effects of differences in crop type, topography and management in these areas. Based on meteorological data, a Geographic Information System (GIS) database and soil and water samples, we propose a new integrated method to monitor SE and NPSP simultaneously and apply to an intensive agricultural area (Nanjing area, ~6 000 km2) in eastern China. The results showed that the levels of soil total nitrogen (TN), total phosphorus (TP), ammonium nitrogen (AN) and available phosphorus (AP) can be used to assess and predict the extent of NPSP and SE status in the study area. Most SE and the greatest NPSP loads occurred between April to August. The most seriously affected area in terms of SE and NPSP was the Jiangning District, implying that the effective management of SE and NPSP in this area should be considered a priority. The sub-regions with higher vegetation coverage contributed to less SE and NPSP, affirming the conclusions of previous studies, namely that vegetation is an effective factor in controlling SE and NPSP. This study shows that the application of our quantitative method has both high precision and reliability for the simultaneous monitoring of SE and NPSP occurring in intensive agricultural areas.