Impacts of typical rainfall processes on nitrogen in typical rainfield of black soil region in Northeast China

摘要

In recent years, non-point source (NPS) pollution has become the main contributor to water quality problems. Research on nitrogen (N) losses from farmland and the factors that influence these losses are very meaningful both in terms of increasing the crop yield and for improving environmental water quality. Hydrological processes are the vector of NPS pollution processes. In this study, 15 different natural rainfalls in the northeast area were monitored to analyze the lost characteristics of nitrogen under different rainfall conditions and the field management measures from July to August of 2013. The results show that total N (TN) content in the rainfalls of 2013 in the drainage area of the Runjin River is 0.18-4.89 mg/L. Judging from the mean flow output of various runoff zones in each rainfall, transverse tilling mode (TTT) < ecological recovery mode (VVR) < no-tillage mode (TNT) < reduced tillage system (TRT) < traditional tilling type (TCT) < bare land (VB). Judging from the mean sand output of various runoff zones in each rainfall, ecological recovery mode (VVR) < no-tillage mode (TNT) < traditional tilling type (TCT) < reduced tillage system (TRT) < traditional tilling type (TCT) < bare land (VB). Moreover, various experimental zones with different tilling systems are distinctively different in the concentration of losses of water-soluble nitrogen and particulate nitrogen and the loss of water-soluble nitrogen and particulate nitrogen per unit area. In the study area, particulate nitrogen carried by runoff sands was the primary forms of nitrogen losses under typical rainfall conditions. The four rainfalls have caused the downward eluviation of nitrogen along the depth of soils to different extents.