稻季施用不同尿素品种的氮素径流和淋溶损失

 在太湖地区乌栅土上,利用大型原状土柱研究不同尿素品种、施肥量处理在稻季氮素径流和淋溶损失.结果表明,包膜尿素在基施情况下,田面水总氮浓度始终接近对照水平,通过径流损失的可能性很小.尿素处理施肥后2d内田面水氮浓度达最高值,随后急剧下降,施肥与径流产生时间的间隔是决定径流氮排放大小的关键因素,施肥5d后的降雨不易造成大的径流排放,氮径流损失与尿素施用量呈显著正相关.各处理间的氮素淋溶排放无显著差异,在2.66～3.25kgN/hm²之间;淋溶液中NO₃^--N浓度最高为0.83mgN/L,在正常施肥情况下,此类土壤氮的淋溶不会造成地下水NO₃--N的严重污染.

Nitrogen loss via runoff and leaching from employ of different urea bleeds in paddy season

The N loss via runoff and leaching from employ amount of different urea bleed in WuShan soil, TaiHu Region was studied using large type of profile-undisturbed monolith lysimeters. Under base employ of the coated urea, the total N concentration of farm surface water was near the contract level, and the possibility via runoff was very little. The N concentration of the farm surface water reached a peak in two days after urea treatments employ, and then decreased quickly. The interval of employ and production time of runoff was the key factor for deciding the amount of runoff N discharge. The runoff discharge was not great by the raining after the employ of 5 days. N runoff loss and urea employ amount emerged markedly positive correlation. There was no obvious difference of N leaching discharge in treatments, which ranged 2.66~3.25kg N/hm2. The highest NO3--N concentration in leachates was 0.83mgN/L, under normal conditions of employ, the N leaching from this kind of soils would not induce serious pollution of NO3--N in the ground water.