水稻田面水氮素动态径流流失特性及控制技术研究

Rule of Lose of Nitrogen in the Surface Water of Rice Fields and the Control Technology

通过测坑和大田试验,对上海市黄浦江上游水稻田面水氮素动态、径流(排水)流失规律和控制对策进行了研究。结果表明,(1)在基肥期和第1次追肥(碳铵)后,稻田水中氮素浓度下降均较快,施肥后1～2d,TN含量即可下降为施肥当天浓度的25.13%～50.25%,平均为30.17%,到第4d则下降到10%以下;(2)在第2、3次追肥(尿素)后,坑面水氮素浓度减少趋势不同于基肥期和第1次追肥,施肥后开始1～3d浓度先稍有升高,此后下降趋势同前2次施肥;(3)人工降雨试验表明,如施肥后遇暴雨,则可能导致氮素的大量流失。以基肥期为例,施肥后第2d,40mm雨量引起的TN流失量为5.54～7.95kg·hm-2,80mm雨量引起的TN流失量可达16.74～24.02kg·hm-2,氮素的径流流失以NH4+-N为主;(4)应严格控制播期排水和烤田排水,否则会引起氮素的大量流失;(5)经测产,增施有机肥而减少化肥用量对水稻产量没有影响,但可以在很大程度上减少水稻田面水氮素的径流(排水)流失。

Through the testing-hole and rice-fields pa ra digm experiment,the rul e of runoff loss of fertilizing-N and controlling cou ntermeasures in rice fields in th e upstream area of HuangPu River wate rshed we re studied.The results were as follows:1)After the first and second fertiliz ation(NH 4 HCO 3 ),the concentration of total nitroge n in the surface water of rice fields decreased rapidly,being 25.13%～50.25%of the initial concentration 1～2days after fertilization and lower than 10%after 4days.2)In the th ird and forth fertilization(CO(NH) 2 ),the concentration of total nitrogen increased a little 1～3days after fe rtilization then decreased,which was different from the first an d second fe rtilization.3)The man-made-raining experiment sh owed that rainstorm afte r fer-tilization caused the great loss of nitrogen.The loss amount of total ni trogen was 5.54～7.95kg·hm-2 in the first fertilization when encountering 40mmrainstorm1day after fert ilization and that reached 16.74～24.02kg·hm-2 if the rainstormwas 80mm.NH 4+-N was the main form of the runoff loss.4)The drainage in seeding and ba king period should be controlled strictly t o prevent the loss of nitrogen.5) Increasing the usage of organic fertilizers and reducing the usage of chemical f ertilizers had no effect on rice yield,but that largely reduced the drainage a n d runoff loss of nitrogen and was an effective measure to protect the agric ul tural water environ-ment.