中文摘要：

通过田间定位监测和分析，研究了上海沟干泥水稻土稻麦轮作下土壤系统中氮的迁移及流失对水环境的影响。结果表明，稻季和麦季土壤渗漏和径流水中氮的形态和浓度是不同的，施肥对氮流失影响程度也不同。稻季土壤渗漏水氮浓度普遍较低，施肥对降雨径流中氮流失有一定影响，且以NH4^＋-N为主。麦季施肥对径流和渗漏水氮流失影响均较大，氮流失以NO3^-N为主，且施碳铵肥的径流水中NH4^＋-N浓度明显增加。麦季土壤渗漏水和径流水中氮浓度普遍接近或超过环境水质标准，是主要的农田污染源。本次水旱轮作氮施肥量为413．5kg·hm^-2，进入地表和地下水氮总流失量为25、32kg·hm^-2，占当年施肥量的3．66％。

英文摘要：

A field experiment was conducted in a rice-wheat planting soil in Nanxiang of Jiading, Shanghai. The study was focused on the nitrogen migration in the soil system and the effect of nitrogen loss on the water environment. The results showed that the nitrogen species and concentrations of soil leakage and runoff were different between paddy season and wheat season, and the effect of N fertilizer application on nitrogen loss also varied with growing plants. The N concentration in leaching water was generally low in the paddy season, and average concentrations of NH4^＋-N and NO3^--N in the superficial underground water at 120-cm depth were 0.3 and 0.71 mg·L^-1, respectively. Higher N concentration in runoff water occurred 5 days after fertilization nitrogen, and NH4^＋-N was dominant, being more than 5 mg· L^-1, except for that the concentrations of NH4^＋-N in the runoff were lower than 1 mg· L^-1. N fertilizer application had great effect on nitrogen loss, especially the loss of NO3^--N in both leaching water and runoff in the wheat season. The NO3^--N concentration in the superficial underground water at 120- cm depth ranged from 5.7 to 8.67 mg·L^-1, while the NO3^--N in the surface runoff was 3.96-9.53 mg·L^-1, indicating that the NH4^＋-N in the runoff increased with the ammonia carbonate（NH4^＋-N） fertilizer application. Both N concentrations in leaching water and surface runoff were generally close to or exceeded the water quality standard, which was the main source of pollution in the farm land in the wheat season. Under the application rate of 413.5 kgN· hm^-2·a^-1, the total N loss by water was 25.32 kg· hm^-2, accounting for 3.66% of the total N application annually.