不同地力水平和施氮量下水稻优质高产的氮肥有机替代比例

  【目的】  氮肥有机替代可减少化肥投入同时消纳有机废弃物，是促进水稻绿色生产的关键技术之一。然而，适宜的氮肥有机替代比例还有待进一步明确。  【方法】  本研究综合已发表有关水稻氮肥有机替代的71篇文章，分别获取水稻产量和籽粒含氮量田间试验相关数据412组和133组，通过整合分析(meta-analysis)量化不同氮肥有机替代比例对水稻产量和籽粒含氮量的影响，并探究不同土壤条件和施氮水平下适宜的有机替代比例。  【结果】  适宜的氮肥有机替代比例有利于水稻产量和籽粒含氮量的提升，土壤有机质含量高(>25 g/kg)、中(15～25 g/kg)、低(≤15 g/kg)水平下，获取最高水稻产量的适宜有机替代比例分别是60%、70%、30%；无论土壤全氮含量高(>1.5 g/kg)、中(1～1.5 g/kg)或者低(≤1 g/kg)，适宜的有机替代比例均不超过60%。土壤速效氮含量高(>150 mg/kg)和低(≤90 mg/kg)水平下，适宜的有机替代比例均是10%～30%，速效氮中等水平下(90～150 mg/kg) 有机替代处理产量增加不显著。高水平施氮量(>250 kg/hm2)下产量最高的有机替代比例为20%，低水平施氮量(≤150 kg/hm2)下产量最高的有机替代比例为10%，中水平施氮量(150～250 kg/hm2)下产量最高的有机替代比例为70%。随着有机替代比例的增加，水稻籽粒含氮量呈现先增后降趋势，含氮量最高的有机替代比例为30%。  【结论】  土壤有机质和全氮含量高的地区，氮肥有机替代比例可以适当提高到60%～70%，中低水平地区有机替代比例则需降低至30%左右。土壤速效氮含量高和低水平下，有机替代比例超过30%，水稻增产不显著或显著降低。施氮量高和低水平下，维持水稻高产的适宜有机替代比例分别是20%和10%。在氮肥有机替代比例不超过30%的情况下，水稻籽粒的含氮量能显著提高。

A suitable replacement ratio of organic nitrogen for high rice yield and quality under different soil fertility levels and nitrogen application rates

  【Objective】  Organic substitution of nitrogen (N) fertilizers to reduce chemical fertilizer inputs and eliminate organic wastes is one of the key technologies promoting green rice production. However, the appropriate substitution ratio of organic N fertilizer is yet to be established, requiring urgent attention.  method  In this study, we synthesized 71 published articles on the organic substitution of N fertilizer in rice production. 412 and 133 field trial data were obtained on rice yield and grain N content. We used meta-analysis to quantify the effect of the rate of organic N substitution (RS) on rice yield and grain N content to explore the appropriate RS under different soil conditions and N application levels.  【Results】  Appropriate replacement of organic N fertilizer improved rice yield and grain N content. The soil organic matter content recorded ranged from high (>25 g/kg), medium (15–25 g/kg), to low (≤15 g/kg) levels. The suitable RS for obtaining the highest rice yield were 60%, 70%, and 30%, respectively. When the soil total N was high (>1.5 g/kg), medium (1–1.5 g/kg) or low (≤1 g/kg), the suitable RS was not more than 60%. Under high (>150 mg/kg) and low (≤90 mg/kg) levels of soil available N, the suitable RS was 10%–30%. At the medium level of soil available N (90–150 mg/kg), RS did not influence rice yield (P>0.05). Under the high N application rate (>250 kg/hm2), the RS with the highest yield was 20%, 10% for low N (≤150 kg/hm2), and 70% for medium N (150–250 kg/hm2). With the increase of RS, the nitrogen content of rice grains increased first and then decreased. The RS with the highest nitrogen content was 30%.  【Conclusion】  The RS can be appropriately increased to 60%–70% in areas with high soil organic matter and total nitrogen content. The RS needs to be reduced to about 30% in low and medium levels. Under the high and low levels of available soil nitrogen, there was no change in rice yield when the RS was more than 30%. The optimum RS for maintaining high rice yield was 20% and 10% under high and low nitrogen application levels, respectively. The N content of rice grains could increase when RS is not more than 30%.