中文摘要：

进行了连续3年6季的定位试验,比较了不施氮（N0）、常规施氮（NNL）2个对照处理与6个氮肥减施处理对双季稻产量及其构成因素、经济效益、土壤肥力水平的影响。结果表明,在低于传统施氮量20%的条件下,30%常规氮肥用量＋50%厩肥有机氮肥用量（30F＋50M）、30%常规氮肥用量＋50%缓释氮肥用量（30F＋50S）产量与NNL持平,比80%传统氮肥用量（80F）分别增产4.7%和5.2%;其余减施氮肥处理与80F产量基本持平。产量构成因子在不同施氮处理之间有明显差异,其中有效穗数、每穗粒数与产量正相关,结实率与产量负相关。经过3年6季水稻种植,土壤肥力除有效钾外,处理30F＋50M有机质、全氮、碱解氮、有效磷含量和pH值分别比NNL处理提高了21.3%、7.0%、34.7%、4.9%、4.1%。其中,有机质、有效磷含量、pH值均显著高于80F处理。其余各减施氮肥处理与80F相比无显著差异。因此,在南方双季稻连作区,在减少施氮20%的条件下,30F＋50M、30F＋50S是值得推荐的施肥措施。

英文摘要：

The grain yield and its components, economic benefits and soil fertility level were compared under eight treatments, namely zero nitrogen （N0）, normal nitrogen level （NNL）, 80% NNL （chemical fertilizers ）and 20% farmyard manure （80F＋ 20M）, 80 % NNI. （chemical fertilizers）, 30 % NNL（chemical fertilizers ） and 50 % farmyard manure （30F＋50M）, 30% NNL（ehemical fertilizers） and 500/00 controlled-release nitrogen （30F＋50S）, 30% NNI. （chemical fertilizers） and 50% green manure nitrogen in early rice and 80% NNL（chemical fertilizers ）and fresh rice straw in late rice, and 80% controlled-release nitrogen in a 3-year location test in South Jiangxi Province of China with the same Pand K application levels. Under 30F＋50Mtreatment and 30F＋50Streatment, the grain yield were 4.7% and 5. 2% higher than that in 80F, respectively, equal to NNL treatment. There was obvious difference in yield components factors among different nitrogen treatments. The effective panicle number per hectare and the spikelet number per panicle were significantly positively correlated with grain yield and seed setting rate was negatively correlatrrd with grain yield. Soil organic matter, total nitrogen, available nitrogen, available phosphorus contents and pH value in treatment 30F ＋ 50M were higher than that in NNL treatment by 21.3%, 7.0%, 34. 7%, 4. 9% and 4. 1%. The organic matter, available phosphorus, pH value were significantly higher than that in 80F treatment. There was no significant difference in other nitrogen reduction treatment compared with 80F treatment. Therefore, 30F ＋ 50M, 30F ＋ 50S were recommended as the methods of fertilizer application with nitrogen reduction of 20% in double-rice cropping region in South China.