东北雨养玉米氮肥优化管理综合评价

Comprehensive assessment of nitrogen fertilizer management for maize in Northeast rainfed region

【目的】针对目前氮肥优化管理的评价方法难以兼顾产量、经济效益、氮肥效率及环境等多目标评价现状,运用层次分析法和熵权法确定指标的权重,并采用综合评价法对玉米氮肥优化管理进行评价。【方法】2018—2019年在东北雨养区开展玉米田间定位试验,试验设5个施氮水平:0 (N0)、75 (N75)、150 (N150)、225(N225)、300 (N300) kg/hm2。在收获期取样,测定玉米产量、氮肥效率、0—100 cm土壤氮素含量。分析氮肥施用量与玉米产量、边际效益、氮素回收率、氮肥农学效率、氮肥偏生产力、氮素生理利用率、氮素表观平衡和土壤无机氮累积量的关系。以高产高效、农田环境友好为总目标层,将其划分为产量、经济效益、氮肥效益和环境4个准则层,准则层又继续划分为8个要素层,依据试验数据确定每个准则层和要素层的权重系数,将不同氮素处理获得的各要素数据归一化后,计算各处理的综合评价分数。【结果】依据试验数据,产量、经济效益、氮肥效益和环境4个准则层的权重系数分别为0.39、0.29、0.10和0.22。8个要素层及其权重系数依次为产量0.39,边际效益0.29,氮素回收率0.025,氮肥农学效率0.025,氮肥偏生产力0.025,氮素生理利用率0.025,氮素表观平衡0.07,土壤无机氮积累量0.15。依据此权重系数计算施氮量处理的综合得分,2018、2019年N225水平分别为0.81、0.92,N150水平分别为0.67、0.78,N75均为0.67,N300水平分别为0.55、0.53,N0均为0.15。选取综合得分高于0.8的施氮量作为推荐量,得出2018年适宜氮肥施用量为N225kg/hm^(2),2019年为N186~225 kg/hm^(2)。【结论】通过分层评估,充分考虑每个目标层的权重,以此对施氮量进行综合评价,得出的适宜施肥量既可满足玉米对氮素的需求,保证玉米获得高产优质,提高氮素利用率,又可降低氮素淋失对环境污染的风险。

【Objectives】We adopted a comprehensive evaluation method to evaluate the current nitrogen fertilizer management for maize considering yield,economic benefit,N fertilizer efficiency and the environment.【Methods】Field experiments were carried out in the rainfed region of Northeast China in 2018 and 2019 with five N application rates:N0,N75,N150,N225 and N300(kg/hm2).Maize yield,nitrogen efficiency and soil N content in 0–100 cm depth were measured at the harvesting stage.The relationship of N application rate with maize yield,marginal benefit,N recovery rate,N agronomy efficiency,partial factor productivity of N fertilizer,N physiological use efficiency,soil N apparent balance and inorganic N accumulation was determined.The highest yield and profit but the least farmland environment risk was set as the top target layer,under it were the four criterion layers,including yield,profit,N fertilizer efficiency and environmental risk.Each criterion layer was further divided into element layers.The weight coefficient of each criterion layer and element layer was determined according to experimental data,and all of the element data were normalized for calculate the comprehensive evaluation scores of each treatment.【Results】The four criterion layers and their weight coefficients were:yield 0.39,profit 0.29,N efficiency 0.10 and environmental risk 0.22,respectively.And there was a total of eight element layers and their weight coefficients were yield 0.39,marginal benefit 0.29,N recovery 0.025,N agronomic efficiency 0.025,N partial productivity 0.025,N physiological utilization efficiency 0.025,soil nitrogen apparent balance 0.07,and soil inorganic nitrogen accumulation 0.15,respectively.According to the weight coefficient,the comprehensive scores of nitrogen application rate N225 were 0.81 and 0.92 in 2018 and 2019;for N150 were 0.67 and 0.78;for N75 was 0.67 in both years;for N300 were 0.55 and 0.53;and for N0 was 0.15 in both years.The N application rate with score higher than 0.8 was deemed optimal for recommendation,which was 225 kg/hm^(2) in 2018 and 186–225 kg/hm^(2) in2019.【Conclusions】Through layering the top target into criterion layer and further into element layers,the effect of each layer of the target was fully considered by its weight coefficient.The optimal N application rate was evaluated comprehensively,hence could meet the requirement for maize yield and profit,and the fertilizer efficiency and environmental safety.