Evaluation method and empirical study of greenhouse gas emissions from a city-scale rice field system based on LCA:taking Taizhou City as an example
Background,aim,and scope Carrying out a chemical assessment of greenhouse gas(GHGs)emissions from rice fields and clarifying the composition and distribution of GHGs from rice fields and their changing trends are important prerequisites for promoting the green and sustainable development of agriculture.Through the assessment of GHGs emissions from paddy fields at the municipal-scale,we can have a more intuitive understanding of the carbon emissions from paddy fields in the mesoscale region,thus providing scientific theoretical support for the sustainable development of rice production.Materials and methods The data were obtained mainly from statistical yearbooks and relevant literature,this study proposes a municipal-scale rice field GHGs emission accounting framework based on the screening of integrated rice field CO2,CH4 and N2O emission assessment models using the life cycle evaluation method,and quantitatively analyzes the composition and distribution of different types of rice GHGs emissions and their changing trends in Taizhou from 2001—2017.Results(1)The total GHGs emissions from rice fields in Taizhou City from 2001—2017 showed a decreasing trend,from 1110.52 Gg to 557.23 Gg;the carbon footprint(CF)per unit area showed an increasing trend and the CF per unit yield showed a decreasing trend;the CF per unit area was highest for single-cropping rice(8467 kg·hm-2)and the highest CF per unit yield for continuous late rice(1.28 kg ? kg-1).(2)In 2017,GHGs emissions from rice were mainly concentrated in Wenling City(131.39 Gg)and Linhai City(121.64 Gg),with the lowest emissions in Yuhuan City(9.37 Gg),and GHGs emissions from early rice and continuous late rice were mainly concentrated in Wenling City.Single-cropping rice is concentrated in Linhai City.(3)Fertilizer accounts for the largest rate(50.46％)in the CF composition of agricultural inputs,and CH4 accounts for the largest rate(75.26％)in the CF structure per unit area.Discussion(1)GHGs emissions from paddy fields are closely related to the local GHGs emission factor,the quantity of agricultural materials inputs and rice yield.The higher amount of agricultural inputs made the paddy field GHGs emissions high.And lower rice yield caused higher CF per unit of yield.(2)In terms of standardization of rice data,all types of rice GHGs emission coefficients and conversion coefficients were accounted for using IPCC standards and relevant statistical yearbooks,and by comparing with the data of related studies in the whole country and various provinces and regions,our findings are consistent with them.Conclusions(1)GHGs emissions from rice fields have obvious characteristics of temporal changes.the total GHGs emissions from rice fields in Taizhou City from 2001 to 2017 showed a decreasing trend,from 1110.52 Gg to 557.23 Gg.The CF per unit area of all three types of rice had an increasing trend,and the CF per unit yield had a slight decreasing trend.(2)There are significant spatial differences in GHGs emissions from rice fields.2017 GHGs emissions from rice are mainly concentrated in Wenling City and Linhai City,while Yuhuan City has the lowest emissions.(3)CH4 is the main contributor in the composition of GHGs emissions from rice fields,and the contribution of chemical fertilizers is also larger.Recommendations and perspectives Improving the utilization rate of production materials,mulching paddy fields,compound farming,returning organic fertilizer to the field after fermentation,appropriate level of nitrogen application,water-saving irrigation,and optimizing planting structure are effective ways to reduce carbon input and GHGs emissions from rice fields in Taizhou.
human-land relationshiplow-carbon agricultureGHGs emissionspaddy systemrural human-land system
张丽华、杨铮、南琼、程钰、李宏庆
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山东师范大学 地理与环境学院,济南 250358
中国科学院沈阳应用生态研究所 中国科学院污染生态与环境工程重点实验室,沈阳 110016
Circular Economy and Recycling Technology,Technical University of Berlin,Berlin 10623,Germany
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