重庆化肥投入驱动因素、减量潜力及环境效应分析

Analysis on Driving Factors,Reduction Potential,and Environmental Effect of Inorganic Fertilizer Input in Chongqing

为定量化揭示重庆市种植业结构变化对化肥投入和环境代价的影响,制定科学合理减肥策略,基于重庆中等生产力水平下农作物化肥定额标准和大样本农户调查数据,采用差值法和生命周期法,评价分析重庆种植业化肥的减施潜力及其环境效益.结果表明:(1)自重庆直辖(1997年)以来,粮食作物(水稻、玉米、小麦、豆类和薯类)播种面积占比下降21%,而水果和蔬菜播种面积占比增加20%.(2)蔬菜(37%)和柑橘(17%)生产系统消耗了近55%的化肥总量,而水稻、玉米和薯类则分别消耗了11%、12%和12%.(3)依2000~2019年化肥总消费量的变化趋势分析“,十四五”期间重庆化肥消费量预计将降至8.6×105t.定额标准全部实现后,总减肥量可达1.69×10^(5)t,减肥潜力为18.6%,其中,水稻、玉米、柑橘和蔬菜的减肥潜力(减肥量)分别为0.3%(2.9×10^(2)t)、12%(1.45×10^(4)t)、21%(3.65×10^(4)t)和30%(1.18×10^(5)t).另一方面,油菜系统表现出磷钾肥不足,玉米表现出钾肥不足态势.(4)当前生产水平下,重庆种植业的氮素损失、温室气体排放量和水体富营养化潜值分别高达1.81×10^(5)t(以N计)、1.43×10^(7)t(以CO_(2)-eq计)和1.74×10^(5)t(以PO_(4)-eq计).随作物定额标准实现程度的增加(60%~100%),活性氮损失、温室气体排放和水体富营养化潜值将分别降低14.9%~24.9%、10.1%~16.7%和13.8%~23%.重庆种植业结构发生了重大变化,化肥消费总量呈缓慢下降趋势,经济作物的施肥强度居高不下.农业化肥减施潜力较大,尤其是柑橘和蔬菜生产系统,但也应注意玉米钾肥和油菜磷钾肥投入不足的问题.

In this study,we sought to quantify the effect of planting structure change on fertilizer input and environmental cost in Chongqing and develop scientific and rational strategies for chemical fertilizer reduction.Based on the crop fertilizer quota standard and large sample farmer survey data under the medium productivity level in Chongqing,we evaluated and analyzed the application reduction potential and environmental benefits of fertilizer with the difference method and life cycle assessment.The results showed that:①since Chongqing became a municipality directly under the central government(1997),Chongqing crop planting structure had greatly changed,and the proportion of food crop(rice,corn,wheat,bean,and potato)decreased by 21%.The area of fruits and vegetables increased from 3.36×10^(5) hm^(2) to 1.05×10^(6) hm^(2),and their proportion increased by 20%.②Nearly 55% of fertilizers had been consumed by vegetable(37%)and citrus production systems,and 11%,12%,and 12% of fertilizers were consumed by rice,corn,and potato,respectively.③The total fertilizer reduction of the Chongqing planting industry could reach up to 1.69×10^(5) tons during the period of"the 14th Five-Year Plan,"with a fertilizer reduction potential of 18.6%.The fertilizer reduction potential(reduction amount)of rice,corn,citrus,and vegetables would reach 0.3%(2.9×10^(2) tons),12%(1.45×10^(4) tons),21%(3.65×10^(4) tons),and 30%(1.18×10^(5) tons),respectively.On the other hand,the rape system was insufficient in phosphorus potassium fertilizers,and the corn tended to be insufficient in potash fertilizer.④The current production level was low,and the nitrogen loss,greenhouse gas emissions,and eutrophication potential in the planting industry of Chongqing reached 1.81×10^(5) tons(N),1.43×10^(7) tons(CO_(2)-eq),and 1.74×10^(5) tons(PO_(4)-eq).With the increase in the realization degree of the crop quota standard(60%-100%),the reactive nitrogen loss,greenhouse gas emissions,and eutrophication potential decreased by 14.9%-24.9%,10.1%-16.7%,and 13.8%-23%,respectively.The structure of the planting industry in Chongqing significantly changed,the total fertilizer consumption in Chongqing tended to decline gradually,and the fertilization intensity of commercial crops stayed at a high level.The agricultural fertilizer reduction potential and the reactive nitrogen and greenhouse gas emission reduction potential were large,especially for citrus and vegetable production systems.However,it is also necessary to pay attention to insufficient corn potash fertilizer and rape phosphorus potassium fertilizer investment and carry out collaborative promotion of fertilizer reduction.