模拟稻田中氮磷的变化特征及其降污潜力分析

为研究稻田中氮磷的变化特征和降污潜力,采用室外微区模拟稻田春耕施肥耕整试验,在3、6cm和9cm等3个不同蓄水深度处理（分别表示为t-3、t-6、t-9）条件下,对稻田氮磷含量变化的动态特征及降污潜力进行了探讨。田面水氮磷质量浓度变化与土壤中氮磷的流失密切相关。土壤扰动、基肥（缓释肥）的释放、硝化-反硝化作用、悬浮颗粒物（SS）的物理沉降等综合因素的影响,是导致田面水氮磷质量浓度变化呈先升后降趋势的主要原因。在蓄水处理后1周内,各处理的田面水氮磷质量浓度大小顺序为：Ct-3〉Ct-6〉Ct-9,总氮（TN）、总磷（TP）质量浓度与蓄水深度呈显著的负相关（Y=-33.97x＋133.4,R2=0.999和y=-0.115x＋0.61,R2=0.994）。春耕插秧时,因水分管理要求,需要立即排水,相对于蓄水3cm的常规水分管理,若能蓄水9cm后再排放,可减少排放总氮45.57%~86.88%、总磷33.02%~62.79%;若蓄水6cm再排放,可减少排放总氮35.76%~72.13%、总磷9.88%~50%。但考虑到＂浅水活苗＂之实际,以人工蓄水5~6cm较为适宜。另外,在蓄水5~6cm的前提下,于第5d或第7d排水,减排降污效果显著;第5d排水,相比第3d排水,可减少排放总氮21.22%~55.41%、总磷67.67%~83.70%。从稻田春耕生产实际要求和降污效能综合考虑,选择6cm的蓄水深度并在第5d排水,是提高稻田减排降污潜力的农艺措施之一。

Changes of nitrogen and phosphorus in the simulated paddy fields and their pollution-reducing potential analysis

To study the changes in nitrogen and phosphorus in paddy fields and its potential ability to reduce pollution,Changes of nitrogen and phosphorus content and their potential of reducing pollution were investigated based on the micro zone-simulated paddy fields after fertilization and spring tillage with the three different water depths of 3 cm,6 cm and 9 cm（expressed as t-3,t-6,t-9,re-spectively）.The results showed that nitrogen and phosphorus content in the field water increased early after fertilization,and then decreased with the time went on,which was caused by the factors such as soil disturbance,release of basic fertilizer（slow-released fertilizer）,nitrification-gentrification and physical sedimentation of the suspended particulate matter（SS）,indicating that changes of nitrogen and phosphorus content in the field water had a close correlation with the loss of nitrogen and phosphorus in the soils.Within a week after impoundment treatment,nitrogen and phosphorus content in the treated field water in the increasing order was t-3t-6t-9,and there was a significant negative correlation between total nitrogen（TN）or total phosphorus（TP）content and field water depth（TN：Y=-33.97x＋133.4,R2 =0.999;TP：y =-0.115x＋0.61,R2=0.994）.Transplanting of rice seedlings during spring tillage required immediate drainage because of water management which was equivalent to the conventional water management at the field water depth of 3cm.When the field water depth reached 9cm,the drainage began,which reduced the emission of total nitrogen of 45.57%~86.88% and total phosphorus of 33.02%~62.79%.The drainage began when field water depth was 6 cm,which reduced the emission of total nitrogen of 35.76%~72.13% and total phosphorus of 9.88%~50%.However,it was proper for 5~6 cm of water depth to good agricultural practice along with good water management ＂seedlings normal growing in shallow water field＂ during rice spring planting.In addition,obvious drain-decreasing and pollution-reducing effect appeared in the drainage of the fifth day or sev-enth day after fertilization and spring tillage in the water depth of 5~6 cm.Emission of total nitrogen and phosphorus can be de-creased by 21.22%~55.41% and 67.67%~83.70%,respectlvey,when draining at the fifth day compared with the third day.As the practical requirements of the spring tillage and pollution-reducing potential were concerned,it should be an agronomic measure to improve the pollution-reducing and drain-decreasing potential when drainage began in the water storage depth of 6 cm at the fifth day.