基于碳足迹的传统农业系统环境影响评价——以青田稻鱼共生系统为例

Environmental impact assessment on traditional agricultural systems based on carbon footprint: a case study of Qingtian rice-fish culture system

现代农业在带来粮食高产的同时也产生许多生态环境问题,这促使人们再次把目光转向传统农业系统。一些传统农业系统不仅具有突出的经济、社会和文化价值,还具有多种重要的生态功能,如温室气体减排。然而,已有研究缺乏对传统农业系统整个生命周期的固碳减排能力的测算及其环境影响的评价。为此,基于农户调研数据,运用生命周期评价法对青田稻鱼共生系统的碳足迹进行了测算,并与当地水稻单作系统进行比较。研究发现:(1)青田稻鱼共生系统和水稻单作系统碳足迹分别为6266.7 kgCO2-eq/hm2和7520.0 kgCO2-eq/hm2,单位产值碳足迹分别为0.12 kgCO2-eq/元和0.21 kgCO2-eq/元。与水稻单作系统相比,稻鱼共生系统排放的温室气体更少,环境影响更小,生态和经济效益更高。(2)农业生产过程中积累的CH4是碳足迹的最主要来源,农业生产资料投入中的化肥是碳足迹的的第二大来源。农业生产资料投入中的饲料则是稻鱼共生系统碳足迹的另一重要来源。通过碳足迹的方法对青田稻鱼共生系统的环境影响进行量化,不仅丰富了碳足迹在实际应用中的适用类型,对于其他传统农业系统的环境影响评价也具有借鉴意义。

Modern agriculture not only brings high yield of grain but also produces many ecological and environmental problems, which urges people to turn their attention to traditional agriculture again. Some traditional agricultural systems not only have outstanding economic, social and cultural values, but also have a variety of important ecological functions, such as GHG emission reduction. Howev er, there were rarely studies to estimate the carbon sequestration and emission reduction capacities of traditional agricultural systems and evaluate their environmental impacts throughout their life cycles. Therefore, the carbon footprint of the rice-fish culture system in Qingtian county, Zhejiang province was measured by life cycle assessment based on the data of farmer surveys, and was compared with that of the local rice monoculture system. The results showed that:(1) the carbon footprints of Qingtian rice-fish culture system and rice monoculture system were 6266.7 kgCO2-eq/hm2 and 7520.0 kgCO2-eq/hm2, respectively, while the carbon footprints of output per unit were 0.12 kgCO2-eq/yuan and 0.21 kgCO2-eq/yuan, respectively. Compared with the rice monoculture system, the rice-fish culture system emitted less greenhouse gas, had less environmental impact, and had higher ecological and economic benefits.(2) The CH4 accumulated in the agricultural production was the main source of carbon footprint, and the fertilizer input to agricultural production materials was the second source of carbon footprint. Feed from agricultural inputs was another important source of carbon footprint of rice-fish culture system. Quantifying the environmental impact of rice-fish culture system in Qingtian by carbon footprint method not only enriches the applicable types of carbon footprint in practical application, but also has reference significance for environmental impact assessment of other traditional agricultural systems.