氮肥后移对引黄灌区水稻产量和氮素淋溶损失的影响

通过田间小区试验研究在优化施肥条件下氮肥后移技术对引黄灌区水稻籽粒产量和氮素渗漏淋失量的影响。结果表明:与农民常规施肥处理(N300)比较,氮肥后移各处理在氮素投入降低20%的基础上水稻产量没有降低,显著提高了氮肥利用率,N240/3处理的氮肥利用率达到40.5%,比N300处理提高了8.8%。田面水中TN和NH4+浓度施肥后1～3d达到最大,而NO3-极大值出现在施肥后3～5d内,之后逐渐降低,施肥后的前9d做好水肥管理是防止氮素流失的关键时期。N300处理氮素渗漏淋失主要发生在分蘖期,氮肥后移处理主要发生在分蘖期和孕穗期,TN渗漏淋失量在29.78～44.51kg/hm2之间,N240/3处理TN淋失量比N300处理降低了33.1%;氮素淋失形态以NO3-为主,占TN淋失量的74.14%～79.44%。综合考虑水稻产量和环境效益,氮肥后移技术N240/3处理可作为一种资源节约和环境友好的施肥技术在水稻种植上应用。

Effect of Postponing N Application on Rice Yield and N Losses in Yellow River Irrigation Area

A field experiment was conducted to study the effect of postponing N application technology on rice yield and the change of characteristics of the concentration of NH+4,NO-3and TN in the surface water and leakage water of the paddy field in Yellow river irrigation area.There are 5 treatments in this experiment,no nitrogen fertilizer(CK),farmer conventional fertilizer treatment(N300),reduction fertilizer treatment(N240),postponing N applicationⅠ(N240/3) and postponing N applicationⅡ(N240/4).The results showed that: N240/3 treatment reduced the amount of nitrogen applied by 20% compared to N300 treatment but had no reduced rice yields significantly.The nitrogen use efficiency of N240/3 treatment was 40.5% which increased by 8.8% compared to N300 treatment.After one to three days nitrogen fertilizer employed each time,the concentration of TN and NH+4 in surface water attaining the bigger value,then decreasing faster.However the concentration of NO-3 in surface water attaining the bigger value at three to five days after nitrogen fertilizer employed each time,9 days after fertilizer employed was the key time to avoid gross of three kinds of nitrogen in the water surface of the paddy field lost.N300 treatment nitrogen leaching occurs mainly in the tillering stage and postponing N application treatments mainly occurs in the tillering stage to flowering stage and NO-3-N was the main form of nitrogen loss,which accounted for TN loss from 74.14% to 79.44%.The amount of N240/3 treatment(29.78 kg/hm2) total nitrogen loss was 14.73 kg/hm2 fewer than FP treatments(44.51 kg/hm2) per hectare and ratio decreased 33.1%.Considering the rice yield and environmental factors,N240/3 treatment was one of environment-friendly technology that could be applied in rice cultivation in Yellow River irrigation area.