太湖流域稻田不同氮肥管理模式下的氮素平衡特征及环境效应评价

研究了不同氮肥管理模式下的稻田氮素平衡特征和环境效应.在太湖主要入湖河流直湖港下游开展了农户常规施肥处理、缓控释肥处理、有机无机肥配施处理、按需施肥处理以及化肥减量优化处理5种氮肥管理模式的田间小区试验，实测了稻季的径流和淋洗氮损失，估算了氨挥发和N₂O等气体损失，分析了不同氮肥处理下的环境排放量和氮素平衡特征.与农户常规施肥处理相比，其他处理在减少氮肥总投入量20%～40%的情况下产量与农户对照基本持平，氮肥利用率提高了14.5%～44%.不同氮肥管理模式下，缓控释肥处理和按需施肥处理的氮环境排放量最低，比农户施肥处理分别降低了52.8%和45.4%.在等氮量投入下，有机无机配施处理比纯化肥处理减少了环境氮排放量.农户施肥处理存在着明显的氮盈余，增加了麦季氮流失的风险，按需施肥处理略微出现氮亏缺，在一定程度上减少了麦季氮流失风险.新型缓控释肥处理和按需施肥处理能在不降低产量和效益的情况下，提高氮肥利用率，减少环境排放量，是值得在太湖流域推广的经济环保氮肥管理模式.

Nitrogen Balance and Environmental Impact of Paddy Field Under Different N Management Methods in Taihu Lake Region

Effects of nitrogen (N) management methods of paddy field on N export to environment and paddy N balance in Taihu lake region, China were studied. Field experiment including site-specific nitrogen management (SSNM), organic & chemical N fertilizer treatment (OCN), control released urea treatment (CRN), reduced chemical N treatment (RN) and farmer's N treatment (FN) were conducted at the taihu lake region in 2008. N loss including runoff, leaching, ammonia volatilization and N₂O were calculated, and the N balance was evaluated. Results showed the grain yield of SSNM, OCN, CRN and RN treatments was identical with FN treatment, while the total N rate reduced about 20%-40%, and N use efficiency (NUE) increased 14.5%-44%. N export of SSNM and CRN treatments decreased 52.8% and 45.4% in comparison with FN treatment. Under the same N input, N export of OCN treatment was lower than pure chemical N treatment (RN). N surplus was observed in FN treatment, while N deficit existed in SSNM treatments. CRN and SSNM treatments could increase NUE, reduce N export without sacrifice of yield and benefit, and could be as an economic and environment-friendly measure to intensify in Taihu lake region.