三峡库区典型粮菜轮作系统施肥管理及环境代价评价

为明确三峡库区两种典型轮作系统的施肥管理现状及其环境代价，随机抽样选取三峡库区腹地涪陵区175个农户进行施肥管理现状调查，从生产力、肥料种类与用量、环境代价和经济效益四个方面进行对比分析榨菜-玉米和榨菜-水稻两种典型粮菜轮作模式，同时设计情景分析，评价优化施肥及新型肥料的施用在降低环境代价方面的作用.结果显示，两个粮菜轮作系统生产力差异不显著，但施肥总量榨菜-玉米轮作系统比榨菜-水稻轮作系统高68.4%，主要原因是玉米种植过程中的氮肥、磷肥和钾肥用量比水稻种植分别高出305kg/hm²、92.3kg/hm²和66.6kg/hm².在施肥过程中，单位收益（每1000元）上榨菜-玉米轮作产生的活性氮损失、酸化效应和富营养化效应分别比榨菜-水稻轮作高147%、73.1%和146%，温室气体效应比榨菜-水稻轮作低38.9%；单位面积（每hm²）上榨菜-玉米轮作体系造成的活性氮损失、酸化效应和富营养化效应比榨菜-水稻轮作体系分别高出44.6%、27.1%和44.1%，而造成的温室气体效应比榨菜-水稻轮作体系低33.3%.运用情景分析方法模拟发现，优化施肥量可以显著的降低环境代价，在优化施肥基础上添加硝化抑制剂可以进一步降低整个轮作体系的活性氮损失、温室气体效应和富营养化效应.本研究为实现源头减量技术防控面源污染提供了理论支撑.

Fertilization and environmental cost assessment of typical grain-vegetable rotation systems in the Three Gorges Reservoir area

This study assessed the current status of fertilization management and its environmental cost for two typical grain-vegetable rotation systems in Three Gorges Reservoir area, which can further provide a scientific and reasonable basis for the green and sustainable development of regional crop rotation systems. A total of 175 farmers in Fuling District of Three Gorges Reservoir area were randomly selected to conduct a survey about the current situation of fertilization management. Two typical grain-vegetable rotation systems including mustard-maize and mustard-rice were compared in term of productivity, fertilizer type and rate, environmental cost and economic benefit. In addition, a scenario analysis was performed to evaluate the effects of optimized fertilization and use of new fertilizer types on reducing environmental costs. Results showed no significant difference in productivity between the two grain-vegetable rotation systems. The total amount of fertilization in the mustard-maize rotation system was 68.4% higher than that in the mustard-rice rotation system. Specifically, the amounts of nitrogen, phosphorus and potassium fertilizers in the maize growing season were 305kg/hm², 92.3kg/hm² and 66.6kg/hm², which were greater than those in the rice growing season. During fertilization process, reactive nitrogen loss, acidification potential and eutrophication potential based on 1000-Yuan profit were 147%, 73.1% and 146%, respectively, greater for the mustard-maize rotation than for the mustard-rice rotation. In contrast global warming potential was 38.9% less for the former. Reactive nitrogen loss, acidification potential and eutrophication potential based on per hectare were 44.6%, 27.1% and 44.1%, respectively, greater for the mustard-maize rotation than for the mustard-rice rotation system, whereas global warming potential was 33.3% less for the former. Results of scenario analysis indicated that optimization of fertilizer application could significantly reduce environmental cost. Optimal fertilization strategy with addition of nitrification inhibitors could further reduce reactive nitrogen loss, global warming potential and eutrophication potential of whole rotation system. This study provides theoretical support for the development of source reduction technology to prevent and control non-point source pollution.