养分管理对直播稻产量和氮肥利用率的影响

为探明不同养分管理模式在实地农户种植条件下对直播水稻产量和氮肥利用率的影响。本试验于2011年6月至2013年11月在江苏省兴化市茅山镇基本农田保护区的田间稻麦轮作条件下，分别选取茅山东村、茅山西村和冯顾村各8个农户，开展3个不同养分管理模式试验，设置了不施肥对照(CK)、农民习惯施肥(FFP)和优化施肥(OPT1和OPT2)4个处理，主要研究了水稻产量及构成因子、氮累积分配和氮肥利用率等对不同养分管理模式的响应。结果表明：(1)施肥较不施肥显著提高水稻产量，优化施肥(226 kg N hm^-2)在较习惯施肥(333 kg N hm^-2)平均减氮32.1%的基础上显著提高水稻产量5.5%，增产原因是提高了穗粒数、结实率和千粒重；OPT2较OPT1平均增产3.1%，其原因是在孕穗期增施了钾肥(18 kg hm^-2 K₂O)。(2)优化施肥水稻植株各部位氮浓度、百千克籽粒需氮量和秸秆氮累积均显著低于习惯施肥，且降低营养器官的氮素分配比例。(3)优化施肥较习惯施肥显著提高水稻氮肥利用率，其氮肥偏生产力(PFP_N)、氮肥农学效率(AE_N)、氮肥回收效率(RE_N)和氮肥生理效率(PE_N)分别平均增加55.5%、79.1%、18.7%和48.7%。(4)水稻植株氮累积与产量呈显著正相关，且优化施肥单位氮累积的增产效果高于习惯施肥。因此，基于氮肥总量控制、分期调控和增施钾肥的养分优化管理措施可在实地农户直播稻种植上协同实现水稻高产和氮肥高效。

Effects of Nutrient Management on Yield and Nitrogen Use Efficiency of Direct Seeding Rice

The effects of different nutrient management models on the yield and nitrogen (N) use efficiency (NUE) of direct seeding rice were investigated under site-specific farmers cultivate practice situation. We conducted a field experiment at eight farmers’ field in basic farmland protection region with a rice-wheat rotation ecosystem in Xinghua County, Maoshan town, Jiangsu Province, from June 2011 to November 2013. Three different nutrient management models and a control were used in this experiment including fertilizer free treatment (CK), farmers’ fertilizer practice (FFP) and optimal fertilizer management 1 and 2 (OPT1 and OPT2). The rice yield and its components, N accumulation and distribution, and NUE were determined. The results showed that the rice grain yield of OPT treatments (226 kg ha^-1 N) significantly increased 5.5% due to the increase of grains per panicle, seed setting percentage, and 1000-grain weight while the N fertilizer application reduced 32.1% as compared with FFP treatment (333 kg ha^-1 N). The rice grain yield of OPT2 treatment was 3.1% higher than that of OPT1 treatment while resulted from increasing potassium application (18 kg ha^-1 K₂O) at booting stage. The N concentration of different parts of plant, N requirement for 100 kg grain, straw N accumulation and N distribution in vegetative organs of OPT treatment were significantly lower than these of FFP treatment. Compared with FFP treatment, OPT treatment also significantly improved NUE of rice plants, in which partial factor productivity of N (PFP_N), agronomic efficiency of N (AE_N), the recovery efficiency of N (RE_N) and physiological efficiency of N (PE_N) increased by 55.5%, 79.1%, 18.8%, and 48.7%, respectively. There was a significantly positive correlation between plant N accumulation and grain yield in rice, and the effect of yield increase per unit N accumulation in OPT treatment was higher than that in FFP treatment. Therefore, the optimal nutrition management model, including controlling total N rate, regulating application stage of N fertilizer and increasing potassium application, can be need to obtain a comprehensive effect for high grain yield and high N fertilizer use efficiency in direct seeding rice planted by farmers.