秸秆生物炭对河套灌区膜下滴灌玉米农田生态系统碳足迹的影响

为探究生物炭对干旱地区膜下滴灌玉米农田生态系统温室气体排放和碳足迹的影响.设置不同施用量的生物炭处理［0（CK）、15（C15）、30（C30）和45 t ·hm^-2（C45）］，连续2 a监测覆膜滴灌条件下一次性施用秸秆生物炭后玉米农田生态系统土壤温室气体（CO₂、N₂O和CH₄）排放的季节变化及其综合增温潜势，利用生命周期评估法估算农业生产活动引起的碳排放量，并进行碳足迹的分析.施用生物炭当年的作物生长季土壤CO₂累积排放量比CK下降17.6%~24.7%，N₂O累积排放量下降71.1%~110.4%，综合增温潜势降低19.5%~25.9%.生物炭施用后第2 a作物生长季的CO₂累积排放量比CK减少19.2%~40.6%，N₂O累积排放量减少38.7%~46.7%，综合增温潜势减少19.7%~40.5%.连续2 a处理C15和C30均不同程度增加了CH₄累积吸收量，而处理C45显著降低了CH₄累积吸收量.C15和C45分别为生物炭施用当年和翌年单位产量碳足迹最少的处理，其单位产量碳足迹较CK分别降低10.1%和26.2%.土壤温室气体排放量对玉米农田生态系统碳足迹贡献率最大（38.1%~59.2%），其次为氮肥生产（19.8%~33.4%），而后为电能生产（6.7%~8.8%）和地膜覆盖（4.4%~7.4%）.生物炭对生态系统碳足迹贡献率为5.7%~13.8%.施用30 t ·hm^-2生物炭对农田生态系统减排固碳增产效果更好.改善生物炭制作工艺及运输途径、提高氮肥利用效率和发展节水节能灌溉技术，是减少旱区农田生态系统碳足迹的重要途径.

Effects of Straw Biochar on Carbon Footprint of Maize Farmland Ecosystem Under Mulched Drip Irrigation in Hetao Irrigation District

To explore the effect of biochar on greenhouse gas emissions and the carbon footprint of a corn farmland ecosystem under drip irrigation with film in an arid region, biochar treatments with different application rates0 (CK), 15 (C15), 30 (C30), and 45 t·hm^-2 (C45)] were established. The seasonal changes in soil greenhouse gases (CO₂, N₂O, and CH₄) and their comprehensive warming potential in the maize farmland ecosystem were monitored for two consecutive years after a one-time application of biochar. The carbon emissions caused by agricultural production activities and their carbon footprint were estimated using the life cycle assessment method. Compared with that in CK, the cumulative CO₂ emissions in the crop growing season decreased by 17.6%-24.7%, the cumulative N₂O emissions decreased by 71.1%-110.4%, and the global warming potential decreased by 19.5%-25.9%. In the second year of the crop growing season after biochar application, the cumulative CO₂ emissions were reduced by 19.2%-40.6%, the cumulative N₂O emissions were reduced by 38.7-46.7%, and the comprehensive warming potential was reduced by 19.7%-40.5%. For two consecutive years, the treatment of C15 and C30 increased the cumulative absorption of CH₄ to different degrees, whereas the treatment of C45 significantly decreased the cumulative absorption of CH₄. C15 and C45 were the treatments with the least carbon footprint per unit yield in the current and the succeeding year of biochar application, and their carbon footprint per unit yield was 10.1% and 26.2% lower than that of CK, respectively. Soil greenhouse gas emissions showed the most contribution to the carbon footprint of the maize farmland ecosystem (38.1%-59.2%), followed by nitrogen fertilizer production (19.8%-33.4%), electric energy production (6.7%-8.8%), and plastic film mulching (4.4%-7.4%). Biochar contributed 5.7%-13.8% to the ecosystem''s carbon footprint. The application of 30 t·hm^-2 biochar had a better effect on carbon reduction, carbon fixation, and yield increase in the farmland ecosystem. Improving the biochar production process and transportation route, increasing nitrogen use efficiency, and developing water-saving and energy-saving irrigation technology are important ways to reduce the carbon footprint of farmland ecosystems in arid regions.