太湖水网地区原位模拟降雨条件下不同农田类型氮素流失特征研究

为探索太湖流域水网地区农田土壤氮素通过地表径流与耕层渗漏的流失特征及其影响因素,在浙江省嘉兴市、上海市的松江县和青浦县,选择稻田、种植年限短的菜地、种植年限长的菜地3种类型农田,采用原位模拟降雨,研究渗漏与地表径流方式下的农田氮素流失量、流失形态特征,以及土壤养分含量对氮素流失的影响。结果表明,3种农田在地表径流方式下农田总氮流失量差异不显著;渗漏方式下种植年限长的菜地和种植年限短的菜地总氮流失量差异也不显著。渗漏方式下总氮流失量显著高于地表径流方式。农田0—5、0—20 cm土壤硝态氮含量分别为31.24~72.9和33.21~71.1 mg/kg时,与渗漏液硝态氮、水溶性总氮、总氮的流失量、流失浓度呈极显著正相关。

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.