江苏省水稻减肥增产的潜力与机制分析

【目的】 明确当前江苏省水稻种植区域的施肥现状与问题,定量研究化学氮肥减量对水稻产量形成和氮素吸收利用的影响,以评估氮肥减量优化在水稻生产中的适用性。【方法】 以江苏省为研究对象,通过对1 502家农户进行调查,分析水稻施氮量（化肥氮）、产量与氮效率（氮肥偏生产力）现状。同时结合文献检索获得的 49篇大田试验文献共 195 组试验数据,采用整合分析方法（Meta-analysis）,定量分析氮肥减量对水稻产量形成和氮素吸收利用的影响特征。【结果】 农户调研数据表明,江苏省农户水稻生产的平均产量、氮肥用量和氮肥偏生产力分别为8 273 kg·hm ^-2、358.10 kg·hm ^-2和 25.12 kg·kg ^-1。文献数据整合分析表明,在江苏地区,与传统/常规施氮相比,氮肥减量显著降低植株氮素吸收量（-5.8%—-14.0%）,在一定程度上抑制了穗数的产生（-2.09%—-5.46%）,同时通过增加穗粒数（3.96%—6.79%）、结实率（2.00%—3.88%）以及千粒重（0.89%—2.10%）来提高水稻产量（2.8%—5.7%）和氮肥偏生产力（52.4%—77.0%）。氮肥减量优化下,籼稻的产量与氮效率的提升效果优于粳稻。减量方式以氮肥减量后进行合理养分运筹同时增施有机肥（秸秆）对水稻增产增效的效果最显著。 减量比例以≤25%最佳。高基础地力条件下更有利于在保证水稻产量的前提下实现氮肥减量。综合分析得出,江苏省水稻的氮肥减量可以通过调控运筹与增施有机肥实现,其推荐减量空间为31%,其中基、蘖肥是其主要的减量方向。 【结论】 江苏省水稻化学氮肥减量可行,基肥与分蘖肥为主要的减量方向。将氮肥减量控制在31%以内,同时进行优化管理,能够合理调控水稻各产量构成因素,实现水稻增产增效。

The Potential and Related Mechanisms of Increasing Rice Yield by Reducing Chemical Nitrogen Application in Jiangsu Province

【Objective】To evaluate the applicability of nitrogen fertilizer reduction and optimization for rice productivity in Jiangsu Province, the current situations and existed problems of fertilizer application were studied, and the effects of reducing nitrogen application on rice yield formation, nitrogen uptake and utilization were quantified.【Method】The current situations of rice nitrogen application rate (chemical nitrogen), grain yield and nitrogen use efficiency (PFP_N, Partial factor productivity of applied nitrogen) were conducted by 1 502 farmer surveys in Jiangsu Province. Moreover, the effect of nitrogen reduction on rice productivity was evaluated by using Meta-analysis with 195 observations from 49 previous published studies. 【Result】The data of farmer practices survey showed that the averaged rice yield, nitrogen application rate and PFP_N in Jiangsu Province were 8 273 kg·hm ^-2, 358.10 kg·hm ^-2 and 25.12 kg·kg ^-1, respectively. Meta-analysis showed that after reducing the N rate, the yield and PFP_N increased by 2.8%-5.7% and 52.4%-77.0%, respectively, compared with traditional/conventional nitrogen application in Jiangsu province. The increased rice yield and PFP_N were attributed to the regulated nitrogen uptake (-5.8%- -14.0%), which reducing the rice panicle number by 2.09%-5.46%, while increasing the grains per panicle, seed setting rate and 1000-grain weight by 3.96%-6.79%, 2.00%-3.88% and 0.89%-2.10%, respectively. The enhancing effects of reducing nitrogen application on rice yield and nitrogen efficiency in indica rice were higher than those of japonica rice. Reducing the nitrogen application based on reasonable nutrient management combined with organic matter (straw) input had the best effects (high yield and high nutrient efficiency). Present study also showed that the best reduction proportion of nitrogen application was supposed to lower than 25%. Moreover, the soils with high fertility were more conducive to achieve nitrogen fertilizer reduction with ensured rice yield. Taken together, the nitrogen reduction of rice in Jiangsu province could be realized by adjusting the nitrogen management and applying organic fertilizer. The recommended reduction space of nitrogen fertilizer was 31%, in which the basal and tillering fertilizers were the main decreasing direction. 【Conclusion】The reduction of chemical nitrogen fertilizer application of rice in Jiangsu province could be achieved while the basal fertilizer and tillering fertilizer should be most considered. The yield components of rice could be controlled reasonably, and the yield and nitrogen utilization efficiency of rice could be improved by reducing nitrogen application when controlling the reduction of nitrogen fertilizer within 31% and combined with optimizing management.