水稻田面水中氮磷素的动态特征研究

Variations of Nitrogen and Phosphorus in Surface Water Body of a Paddy Field

采用独立排灌系统的田间试验研究了水稻田面氮素、磷素的动态特征。结果表明,分次施肥后的次日,田面水中氨氮、总氮浓度明显升高,随着时间的推移,氮素浓度下降很快。特别是第1次施氮后第9d,各处理氨氮浓度分别为施后第1d浓度的1.19%～2.70%,全氮则变为6.03%～18.74%(对照N-I除外)。氨态氮/全氮比值也呈类似趋势,相比较而言,硝态氮含量要远远低于氨氮,最大值为2.07m g·L-1。同时还表现出不同的趋势,其峰值在第3d出现。另外,不同的施氮量的作用下,等量的磷肥所产生的田面效应表现不同,且大体表现为施氮量多者,田面水磷含量也相应多的现象。从环境污染角度考虑,控制氮素、磷素田面流失主要时期为施肥后1周内。

A field experiment with independent irrigation system was conducted to elucidate the dynamic characteristics of nitrogen (N) and phosphorus (P) in surface water of paddy field under different N supply levels in 2003. The results of field experiments showed that split nitrogen fertilizer application with 4 times greatly increased the concentration of ammonia nitrogen (-N) and total nitrogen (TN) in surface water at field initially, then both declined subsequently as the time passed. After the first nitrogen application,the concentrations of -N and TN at 9th day for 6 different treatments were separately in ranges of 1.19%～2.70%, and 6.03%～18.74%(except CK) at first day. The rate of -N/TN had the similar trend as TN, -N. But the concentration of nitrate nitrogen (-N) was lower than the one of and the maximum concentration was 2.07 mg·L-1. It also showed different trends from TN and -N and the peak concentration value appeared after3 days urea employed each time. The same amount of phosphorus application in different nitrogen application treatments showed different results that phosphorusconcentration in the surface water. The P concentration in surface water of paddy had some relationships to nitrogen application amounts. More N application amount produced more P content in surface water of paddy field. In terms of the environment consideration, the period within a week after the fertilizer application was a critical time to control N, P loss and leaching from flooded paddy field.