生物炭添加对土壤冻融过程中温室气体排放的影响

【目的】研究模拟生物炭添加对土壤冻融过程中二氧化碳(CO2)、甲烷(CH4)和氧化亚氮(N2O)排放的影响,为冻融期土壤温室气体的减排提供参考。【方法】以伊犁河谷典型农田为研究对象,野外采集原状土柱,并在室内模拟不同幅度的冻融过程(+5 ℃、-5 ℃～ +5 ℃和-10 ℃ ～ +10 ℃),探求冻融过程中土壤CO2、CH4和N2O排放对生物炭添加(0、20和40 t/hm2)的响应特征。【结果】与不添加生物炭的处理相比,添加生物炭会使冻融过程中的土壤CO2排放量提高1.1～1.4倍,但该影响远小于冻融作用对土壤CO2排放的促进作用(为CK的1.5～3.2倍); 虽然冻融作用未显著(P > 0.05)影响土壤CH4的累积排放量,但生物炭的添加显著(P < 0.05)促进了45.5%～81.8%的CH4吸收量; 冻融作用使土壤N2O的累积排放量提高了1.3～3.0倍,生物炭降低了冻融过程中10.2%～30.9%的土壤N2O排放量,但在多数情况下这种减小并不显著(P > 0.05)。【结论】模拟生物炭添加会增加土壤冻融过程中CO2的排放,也会促进CH4的吸收和N2O的减排。
【Objective】 Investigating the impacts of biochar addition on carbon dioxide(CO2), methane(CH4)and nitrous oxide(N2O)fluxes from soils subjected to freeze-thaw process could provide basis for the mitigation of soil greenhouse gas emissions during freeze-thaw period. 【Method】 Intact soil cores were collected from a cropland in the Ili River Valley and then subjected to freeze-thaw processes with different freeze-thaw amplitudes(+5 ℃, -5 ℃ - +5 ℃ and -10 ℃ - +10 ℃)in the laboratory, to explore the responses of soil CO2, CH4 and N2O fluxes to biochar addition(0, 20 and 40 t/hm2)during freeze-thaw process. 【Result】 CO2 fluxes from soils with biochar additions were 1.1-1.4 times higher than those from soils without adding biochar. However, such increases were lower compared to the promoting effects of freeze-thaw on soil CO2 flux(1.5-3.2 times). Although freeze-thaw process did not significantly(P > 0.05)affect the cumulative flux of soil CH4, biochar additions significantly(P < 0.05)increased soil CH4 flux by approximately 45.5%-81.8%. Biochar decreased soil N2O flux by 10.2%-30.9% during freeze-thaw process, but such decreases were not significant(P > 0.05)in most cases. 【Conclusion】 Biochar addition may increase the emission of soil CO2, while promote the uptake of soil CH4 and the mitigation of soil N2O during freeze-thaw process