Nitrogen losses under simulated rainfall conditions in different cropping lands of Taihu Lake region

Field trials of simulated rainfall were carried out to study N losses through leakage and runoff, and effects of soil NO-3-N content on N loss. The main results show that under the way of runoff, there are not obvious differences of total N loss among the 3 cropland types, and there are also not obvious differences between the 2 vegetable field types under the way of leakage. The total N loss from leakage is significantly higher than that of runoff, and the analysis of different N forms shows that NO-3-N is the main form. Results from the leakage experiments indicate that when soil NO-3-N contents at 0-5 and 0-20 cm are 31.2-472.9 and 33.2-171.1 mg/kg, respectively, there are significant correlations between the soil NO-3-N contents at 0-5 cm or 0-20 cm and the concentrations or amounts of total nitrogen, total dissolved nitrogen and NO-3-N in the leakage.