基于生命周期评价的相同食物当量玉米与紫花苜蓿生产环境影响比较研究

Use of life cycle assessment methodology to compare environmental impacts of the same food equivalent for corn and alfalfa production

为了探讨种植业结构调整对于我国环境的影响,本研究运用生命周期评价方法,计算了甘肃省民勤县农户水平2014与2015年从农资生产到农户入仓范围生产1kg玉米籽粒及1kg紫花苜蓿鲜草的环境影响,并使用基于蛋白质和热量的计量单位——食物当量(FEU),比较分析了1个FEU玉米籽粒和紫花苜蓿生产的全生命周期环境影响差异。结果表明,生产1kg玉米籽粒和1kg紫花苜蓿鲜草全生命周期的一次性能源消耗(PED)分别为9.35和1.22 MJ,水资源消耗(WU)分别为889.33和144.37kg,矿物和化石资源消耗(DAR)分别为0.13和0.02kg antimony-eq,气候变化潜值(GWP)分别为1.21和0.10kg CO_2-eq,可吸入无机物(RI)分别为4.23×10^(-3)和1.88×10^(-4) kg PM2.5-eq,光化学臭氧合成(POFP)分别为2.41×10^(-3)和1.71×10^(-4) kg NMVOC-eq,环境酸化潜值(AP)分别为8.55×10^(-3)和8.03×10^(-4) kg SO_2-eq,淡水富营养化(FEP)分别为1.20和0.09kg P-eq,生态毒性(ecotoxicity)分别为1.26×10^(-2)和1.49×10^(-3) CTU。1个FEU紫花苜蓿生产的PED、WU、DAR、GWP、RI、POFP、AP、FEP和ecotoxicity则分别为玉米籽粒的20.50%、25.43%、21.08%、12.99%、6.98%、11.15%、14.76%、12.31%和18.58%。因而考虑到苜蓿的食物-经济比较优势,目前应给予其不少于粮食作物的种植补贴。并且如果将我国的部分玉米种植改为苜蓿种植,则是最便捷、经济的既能满足我国食物结构需求,又能减少农业生产的资源消耗与环境污染的措施。本研究同时也为在我国深入开展粮改饲提供了一定的立论基础。

The study used life cycle assessment （LCA） methodology to calculate environmental impacts of pro-ducing 1 kg of corn and 1 kg of alfalfa for animal feed, from agricultural raw materials, including cultivation and other aspects of on farm production and associated transport. Data used are for the years 2014 and 2015. The calculation predicts how structural adjustment to crop production patterns will affect China？s environ-ment. In addition, the life cycle environmental impact differences between production of 1 food equivalent unit （FEU） of corn and alfalfa were compared with calculations based on protein and energy content. It was found that life cycle environmental impacts of 1 kg of corn and 1 kg of alfalfa, respectively, were 9. 35 and 1. 22 MJ of primary energy demand （PED） , 889. 33 and 144. 37 kg of water use （WU） , 0 . 13 and 0. 02 kg antimony-eq of depletion of abiotic resources （DAR） , 1. 21 and 0 . 10 kg C 0 2-eq of global warming potential （GWP） , 4. 23 and 0. 19 g PM2.5-eq of respiratory inorganics （RI） , 2. 41 and 0 . 17 g NMVOC-eq of photochemical oxidant forma-tion potential （POFP） , 0. 00855 and 0 . 00080 kg S 0 2-eq of acidification potential （AP） , 1. 20 and 0 . 09 kg P-eq of freshwater eutrophication potential （FEP） , and 0 . 0126 and 0. 0015 CTU of ecotoxicity. Meanwhile, life cycle environmental impacts of 1 FEU alfalfa compared to corn are： PED 20. 50% , WU 25. 43% , DAR 21. 08% , GWP 12. 99% , RI 6. 98% , POFP 11. 15 % , AP 14. 7 6%, FEP 12. 31 % , and ecotoxicity 18. 58%. In view of the ecological and economic superiority of alfalfa, subsidies no less than those for other grains should be given. Moreover, agricultural reform such as shifting corn production to alfalfa, cannot only help meet China？s food requirements internally, but also is a convenient and economical way to reduce the resource consumption and environmental pollution in agricultural production. This study provides a scientific basis for a policy to shift from grain to forage production in China.