优化施肥和缓释肥对水稻田面水氮磷动态变化的影响

Dynamic Variation of Nitrogen and Phosphorus Under Optimize Fertilization and Slow-release Fertilizer in Paddy Field Surface Water

通过小区试验探索优化氮肥分次施用及缓释肥对稻田氮磷形态和动态变化的影响,结果表明,田面水TN浓度在施肥后的第1天达到最大,NH4+-N峰值出现在施肥后的第2天,随氮素的转化,NO3--N浓度在第4天达到高峰。总体上NH4+-N是稻田田面水氮素的主要表现形态,而农田灌溉和降雨可显著提高NO3--N的比例。总磷浓度在基肥施用后的第2天达到高峰,在基肥施用后的第7天和灌溉或降雨农田被扰动后的第2～3天稻田田面水总磷浓度出现回升现象。农田灌水及天然降雨也可使田面水中可溶性磷呈现降低趋势,颗粒态磷的比例升高。水稻生育初期的径流水中总氮、总磷相对较高,远远超出地表水环境质量标准Ⅴ类水的标准限值(TN 2.0mg/L,湖、库TP 0.2mg/L)。平均4次产流中,相对于传统施肥,优化施肥氮肥分次施用及缓释肥处理产生的径流中总氮浓度可降低约22.98%～42.88%。

This paper explores the effect of nitrogen fertilizer applicated in several times and slow-release fertilizer work on dynamic changes of nitrogen and phosphorus in paddy fields on the condition of natural rainfall and irrigation through field experiment.the results showed that the TN concentration of the surface water reached the maximum on the first day after fertilization and NH＋4-N in the second day.With the conversion of nitrogen,NO-3-N concentrations peaked in the 4th day.NH＋4-N was the main formation of nitrogen of surface water generally,and irrigation and natural rainfall could significantly increase the proportion of NO-3-N.The TP concentration peaked on the 2nd day after fertilization and rebounded on the 7th day after fertilization or in 2～3 days when the field was disturbed by irrigation or rainfall.The irrigation and natural rainfall could also decreased the soluble phosphorus of surface water and increase the proportion of particulate phosphorus.The TN,TP of the runoff were relatively high in the early stage of the growth of rice,far beyond the standard limit of Ⅴ water of the surface water quality standards（TN 2.0 mg/L,TP 0.2 mg/L of lakes and reservoirs）.Compared to the treatment of conventional fertilization,using nitrogen in several times and slow-release fertilizer could decreased by 22.98%～42.88% of TN concentration.