稻作期氮素渗漏流失特性及控制对策研究

Characteristics of Nitrogen Loss in the Leakage Water of Rice Fields and the Control Measurements

通过测坑定位试验,对上海市黄浦江上游水稻田氮素渗漏流失规律及其控制对策进行了研究,得到如下结论:(1)稻田氮素渗漏流失以NO3--N为主,施肥后1~2 d渗漏水中NH4+-N浓度较高,之后一般为0.19~2.83 mg.L-1;(2)受稻前旱作(草莓)的影响,水稻生长前期渗漏水中NO3--N的含量高达30~50 mg.L-1,随着田面水的不断下渗淋洗作用,到了稻作后半期,NO3--N的含量下降到较低水平,约为2~3 mg.L-1;(3)在整个稻作期(截止到9月20日)TN的渗漏流失量为22.65~30.57 kg.hm-2,其中NO3--N为18.59~24.90 kg.hm-2,平均为总流失量的82.64%;(4)使用有机肥替代化肥可以在很大程度上减少稻田氮素渗漏流失,在化肥用量减少20%~30%的情况下,氮素渗漏流失量可以减少19.43%~25.91%;(5)经测产,增施有机肥而减少化肥用量对水稻产量没有显著影响,但在很大程度上减少稻田氮素的渗漏流失,对减少农业氮素面源污染、保护地下水具有重要意义。

Through the leaching-pond experiment,the rule of leakage-loss of nitrogen and controlling countermeasures in rice fields in the upstream area of HuangPu River watershed were studied.The following results were obtained:(1) Nitrogen in the leakage-water existed mainly in the form of NO_3-N,and the concentration of NH_4^+-N in the leakage-water was only about 0.19～2.83 mg·L^(-1).(2) Under the influence of previous non-water-cultivation,the concentration of NO_3~——N in the leakage-water reached 30～50 mg·L^(-1) during early growing period of rice and was about 2～3 mg·L^(-1) in the later period.(3) Total nitrogen loss amount during rice growing period was about 22.65～30.57 kg·hm^(-2),in which NO_3~——N accounted for 82.64%,being about 18.59～24.90 kg·hm^(-2);(4) Applying organic fertilizers and reducing chemical fertilizers in rice fields could reduce N leakage loss to a large degree,20%～30% reduction of chemical fertilizers application could reduce 19.43%～25.91% of the N leakage loss amount;(5) Increasing the application rates of organic fertilizers and reducing chemical fertilizers had no remarkable effects on yields of the rice but could reduce N leakage loss largely,which was an effective measure to abate agricultural non-point source pollution and protect the groundwater.