Nitrogen-NPSP In Agro-ecosystem Of Small Watershed In Hilly Area Of Central Sichuan

With the sharp increase application of chemical nitrogen fertilizers and farm manure used to agriculture, much attention is focused on non-point source pollution of nitrogen and effects on environment and human's health. So that, non-point sources pollution of nitrogen becomes a crucial problem. Agricultural non-point source pollution has been attracted more and more attention because of eutrophication and nitrate contamination to the surface and ground water. Since 1980s, surface water of lakes, reservoirs and rivers in different region of China were seriously polluted by non-point source pollutant, which are menacing human's health and national sustainable development.Purple soil distributes widely in hilly regions of the upper reaches of Yangtze River, especially in the Sichuan Basin, which is the most important agricultural area in Sichuan province. However, heavy runoff and soil erosion of purplee soil not only leads to soil degradation and decrease of water environment aquality locally, but also brings heavy pressure to sustainable development of Yangtze River. In this research, a typical agricultural catchment ecosystem in the hilly area was chosen as a case for studies on formation situation, mechanism and effects of non-point source polluiton of nitrogen so as to provide scientific bases for control on non-point source pollution in the hilly area of purple soil.Nitrogen non-point sources pollution researches were carried out in Yanting agro-ecological station (CAS)watershed. Nitrogen input-output and transportation observation was conducted in different location of farmlands, surface water and runoff plots. From Apr.2002 to Apr.2003, nitrogen concentrations and forms of runoff, sediment and surface-ground water in this small watershed were monitored twice a month with two replicates. After crops were harvested in the dry season, nitrogen contents of soil and sediment sludge samples in pond and runoff drainage were tested. Nitrogen pollution load was calculated based on above observed and investigated data. Impact of non-point sources pollution of nitrogen on the environment was discussed in this paper. Results showed,In the upland runoff and surface water in the paddy fields, particle nitrogen contributes 35% and 37% to total nitrogen(TN) respectively. Average concentration of total nitrogen in fameland runoff was in following sequence: SNTRCS (seasonal no-tillage ridge cropping system)