油菜秸秆不同还田方式下水稻碳足迹分析

Carbon footprints of rice under different managements of rapeseed straw

【目的】四川盆地“油菜—水稻”复种模式下油菜秸秆还田是秸秆高效处理的重要途径。明确不同油菜秸秆还田方式对水稻碳足迹的影响,对秸秆低碳绿色利用及“油菜—水稻”复种系统可持续生产具有重要指导意义。【方法】以油菜秸秆不还田(CK)为对照,采用基于LCA土壤碳库法的碳足迹计算方法分析比较了油菜秸秆覆盖还田(S1)与油菜秸秆翻埋还田(S2)处理下的水稻碳足迹。【结果】①CK、S1与S2处理下水稻碳足迹分别为0.12、-0.08、0.02 kg CO_(2)-eq/kg,尽管油菜秸秆还田增加了194.5 kg/hm^(2)的CH_(4)排放,但与CK相比,S1和S2显著增加了土壤有机碳储量变化,其增量分别为2193.0、2019.3 kg C/hm^(2);②稻田CH_(4)排放是水稻碳足迹的重要构成,其次是农资生产和使用造成的温室气体排放,其中复合肥投入是农资温室气体排放的主要贡献因素,占总农资温室气体排放的73.9%。【结论】与油菜秸秆不还田相比,油菜秸秆还田增加了土壤有机碳储量从而减少了水稻生产碳足迹,如何减少因油菜秸秆还田和化肥投入增加的温室气体排放,是进一步减少水稻碳足迹、促进水稻低碳生产的重要途径。

【Objective】Rapeseed straw incorporation was a high-efficient way of straw management under the‘rapeseed-rice’multiple cropping system in the Sichuan Basin.It was important to clarify the impact of different rapeseed straw management on the carbon footprint of rice production,which can guide the low-carbon utilization of rapeseed straw and the sustainable production of rice.【Method】This study applied a LCA-based carbon footprint methodology,which includes the change of soil carbon,to analyze and compare the carbon footprints of rice production under three treatments:rapeseed straw remove(CK)as a control,rapeseed straw mulching(S1),and rapeseed straw incorporation(S2).【Result】(i)The carbon footprints of rice under CK,S1 and S2 treatments was 0.12,-0.08,and 0.02 kg CO_(2)-eq/kg,respectively.Although the management of rapeseed straw returning to the paddy increased CHemission by 194.5 kg/hm^(2),compared with CK,S1 and S2 significantly increased the change of soil organic carbon storage by 2193.0 and 2019.3 kg C/hm^(2),respectively;(ii)CHemission from paddy was a major contributor of the carbon footprint,and the second one was the greenhouse gas emissions caused by the production and use of agricultural inputs.Compound fertilizer was the main contributor of greenhouse gas emissions caused by agricultural inputs,accounting for 73.9%of the total greenhouse gas emissions.【Conclusion】Compared with rapeseed straw removing,rapeseed straw returning to the paddy increased soil organic carbon storage and reduced the carbon footprint of rice production.Reducing the greenhouse gas emissions increased by rapeseed straw returning to the paddy and fertilizer input would be a crucial approach to further reduce the carbon footprint of rice and promote low-carbon rice production.