滇池北岸典型农区韭菜田大气氮湿沉降与氮挥发研究

选择滇池北岸大清河下游典型农区韭菜田为对象,对雨水进行化学分析,研究了2007年大气氮湿沉降通量及其动态变化,并通过田间试验观测了地表(韭菜地土壤、韭菜废弃物原位腐解、沟渠污水)的氨氮挥发.结果表明,全年大气湿沉降氮(以N计)7.1kg/hm2,其中雨季(4～9月份)占89%.韭菜一次基施尿素(以N计)276kg/hm2,35d累计氨挥发占施氮量的32%,其中前9d氨挥发占总氨挥发96%.韭菜残体腐解21d累计氮挥发占植株氮23%.含氮7～51mg/L的污水(其中氨氮2.7～25.8mg/L)露天放置12d,水体总氮的27%～38%挥发进入大气.可见,韭菜田氮挥发是该地大气氮重要来源之一.

Atmospheric nitrogen wet deposition and nitrogen volatilization in Chinese chive planting field of a typical agricultural area at northern bank of Dianchi Lake

One–year monitoring study was conducted to estimate wet N deposition to in Chinese chive planting field of a typical agricultural area at northern bank of Dianchi Lake. Nitrogen volatilization was also investigated in soils of Chinese chive planting fields, in situ field Chinese chive decomposition, and in ditch sewage water. The total wet N deposition was 7.1kg N/hm2 in 2007, about 89% of N deposition occurred during the rainy season of April to September. The cumulative ammonia volatilization loss 35days after N fertilization accounted for 25% of supply N as urea (345 kg N/hm2), about 96% of ammonia volatilization loss occurred during the first 9days after N fertilization. The cumulative N volatilization loss accounted for 27%~38% of total N in the ditch sewage water containing 7~51mg N/L (2.7~25.8mg N/L as NH3-N) within open storage for 12days. Therefore, nitrogen volatilization in Chinese chive planting fields could be one of important sources of atmospheric nitrogen in the present investigation area.