湖北省稻田地表径流氮磷养分流失规律初探

在湖北省水稻主要种植区设置3个田间原位监测点,采用径流池收集地表径流的方法,研究水稻田地表径流产生和氮磷养分流失的规律.结果表明,2010年,全省稻田平均产生地表径流8次,产流量平均为304.5 mm,产流系数为34.7％,径流主要发生在4～8月降雨比较集中的时段；施肥后全省稻田年平均总氮的流失量为4.90-10.67 kg/hm2,总磷流失量为0.63～1.44 kg/hm2;径流水中总氮平均浓度为1.83～3.83 mg/L,总磷浓度为0.16～0.49 mg/L;可溶态氮是地表径流氮素流失的主要形态,约占总氮的70.2％～86.7％,其中尤以硝态氮的流失量最大,占总氮的51.8％～69.5％,铵态氮流失量较小,约占总氮的7.4％～34.9％;磷素的流失以颗粒态磷为主,占总磷的60.4％～87.7％；肥料氮、磷养分流失量平均分别为当季施肥量的0.46％和0.37％.施肥和径流量是影响地表径流氮、磷流失的主要因素,施肥导致氮、磷养分流失量增加,径流产生量大的时段,其氮、磷的流失量也增加.

Regular Pattern of Nitrogen and Phosphorus Losses in Rice Field of Hubei Province

Experimental plots in situ were conducted in the main rice planting regions of Hubei province in 2010,the runoff water in each plot was collected and tested,to investigate the regular pattern of the surface runoff events and the nitrogen and phosphorus losses of the rice field.The results showed that the surface runoff events usually occurred in raining season from April to August.On average,8 times of runoff events occurred in a year,the annual amount of runoff was 304.5 mm and the runoff generation coefficient was 34.7%;the annual amount of nitrogen losses from rice field was 4.90～10.67 kg/hm2,the phosphorus losses was 0.63～1.44 kg/hm2.The mean concentration of nitrogen losses was 1.83～3.83 mg/L and 0.16～0.49 mg/L for the phosphorus.The dissolve nitrogen accounted for 70.2%～86.7% of the nitrogen losses,that was the main way of nitrogen losses,of which the nitrate nitrogen had a percentage of 51.8%～69.5%,and only 7.4%～34.9% for the ammonium nitrogen losses.The particle phosphorus was the predominant losing phosphorus form,which accounted for 60.4%～87.7% of the phosphorus losses.The coefficients of nitrogen and phosphorus losing from runoff was respectively 0.46% and 0.37% of a growing season.It was found that fertilizer and runoff discharge were the two main factors influencing nitrogen and phosphorus losses,the amount of nitrogen and phosphorus losses were improved by fertilization,and also increased with the increasing of runoff amount.