生物炭添加对土壤冻融过程中温室气体排放的影响

Impacts of biochar addition on greenhouse gas fluxes from soils subjected to freeze-thaw process

【目的】研究模拟生物炭添加对土壤冻融过程中二氧化碳(CO_2)、甲烷(CH_4)和氧化亚氮(N_2O)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CO_2、CH_4和N_2O排放对生物炭添加(0、20和40 t/hm^2)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CO_2排放量提高1.1~1.4倍,但该影响远小于冻融作用对土壤CO_2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CH_4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CH_4吸收量;冻融作用使土壤N_2O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N_2O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CO_2的排放,也会促进CH_4的吸收和N_2O的减排。

[ Objective ] Investigating the impacts of biochar addition on carbon dioxide （ CO2 ）, methane （ CH4 ） and ni- trous 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 C02, CH4 and N2O fluxes to biochar addition （0, 20 and 40 t/hm^2 ） during freeze-thaw process. [ Result] C02 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 decrea- ses were not significant （P 〉 0.05） in most cases. [ Conclusion ] Biochar addition may increase the emission of soil C02, while promote the uptake of soil CH4 and the mitigation of soil N2O during freeze-thaw process.