天然降雨条件下水稻田氮磷径流流失特征研究

采用具有单排单灌的试验小区,对水稻田在多次天然降雨条件下形成的径流中氮磷的流失特征进行了研究。结果表明,几次降雨径流的累积量中总氮的最高浓度达到22.15mg/L,总磷的浓度达4.84mg/L,可溶态氮是天然降雨径流流失氮素的主要形态,约占总氮的70%～92%,尤其是硝态氮,约占总氮的40%～80%,而径流流失中氨态氮的浓度较小,仅占总氮浓度的3.4%～27%,颗粒态磷在径流流失磷素中占到较大的比重,可达76%～79%;几次降雨事件中总氮的累积流失负荷约在0.23～0.80kg/hm2,总磷的累积流失负荷约在0.07～0.15kg/hm2,两者都小于当季施肥量的1%;降雨和施肥是影响氮磷素径流输出的主要因子,对降雨、施肥量、氮磷素输出负荷运用二元一次方程进行拟合,结果表明相关性达到了显著性水平。

Study on Characteristic of Nitrogen and Phosphorus Loss from Rice Field by Natural Rainfall Runoff

The characteristics of nitrogen and phosphorus loss from rice field by natural rainfall runoff were studied in Shuangqiao Farm of Jiaxing city, located at the Yangtz river delta region. The experiment was conducted using the fifteen plots method with an irrigation water-supported system. From results, we could get these information as follows: firstly, the highest total nitrogen (TN) concentration was 22.15 mg/L, and 4.84 mg/L for total phosphorus (TP) which exceeded more than the criterion for TN and TP regulated by our national government. Secondly, dissolved nitrogen was the predominant losing nitrogen form in runoff, of which nitrate nitrogen had about a percentage of 40~80, and 3.4~27 percent only for ammonium nitrogen, however, there was 76~79 percent of particular phosphorus moving in runoff. Thirdly, the discharge of nitrogen and phosphorus with runoff losing from rice field was 0.23~0.80 kg/hm~2 and 0.07~0.15 kg/hm~2 respectively, which both was less than one percent of the nitrogen fertilizer input. Finally, it was found that rainfall and fertilizer were two main factors influencing nitrogen and phosphorus loss in runoff, and there was a significant relativity among rainfall, fertilizer input and nitrogen and phosphorus loss load.