模拟人工蓄水条件下拔节孕穗期稻田的氮磷动态特征及其降污潜力

Dynamics of nitrogen and phosphorus in impounded paddy field in jointing and booting stages and its pollution-reducing potential

采用室外微区模拟稻田人工蓄水的控排水技术,在5、10、20cm等3个蓄水深度处理(分别表示为t-5、t-10、t-20)条件下,对拔节孕穗期稻田中氮磷的动态特征及降污潜力进行了研究.结果表明,田面水中TN、NH4+-N和TP浓度与蓄水深度呈显著负相关(y=-2.18x+10.870,R2=0.960;y=-0.048x+2.063,R2=0.999;y=-0.05x+0.223,R2=0.949),即蓄水深度越大,TN、NH4+-N和TP浓度越低.田面水中的NO3--N浓度与蓄水处理相关性不明显,但比较而言,t-20的NO3--N浓度要大于t-5和t-10,并于深施处理第5天后出现反弹升高现象.撒施尿素对田面水中悬浮物(SS)有絮凝沉淀作用,以致在施肥后第2天SS浓度最低.从减排降污综合效能看,在暴雨或大雨频发期,将排水堰高度提高到10～20cm,延长滞留涝水时间5～7d左右,具有显著的减排降污潜力.

Variation characters of nitrogen and phosphorus in the rice field and its pollution-reducing potential Were researched,Using controlled drainage technique in the micro-zone simulated paddy field with the water depth of 5,10 and 20 cm（expressed as t-5,t-10,t-20,respectively）.Concentration of TN,NH4＋-N and TP turned low with the water depth in the field,and showed a significant correlation between them（TN：y=-2.18x＋10.87,R2=0.960;NH4＋-N：y=-0.048x ＋2.063,R2=0.999;TP：y=-0.05x＋0.223,R2=0.949）.NO3--N concentration in the t-20 treatment was higher than that in the t-5 and t-10 treatment,and increased at 5 d after deep application of fertilizer.However,there was not a obvious correlation between NO3--N concentration and water depth in the field.Urea caused the lowest SS concentration to appear at 2 d after application because of its flocculation and sedimentation to the suspended particulates.During heavy rain frequent-occurrence period,drainage weir should be increased by 10-20 cm to extend the water logging time 5-7 d longer to reach the best pollution-reducing potential.