摘要:为了研究生物炭及秸秆还田对干旱区玉米农田温室气体通量的影响，以内蒙古科尔沁地区玉米农田为试验对象，采用静态箱-气相色谱法对分别施入生物炭0 t·hm-2（CK）、15 t·hm-2（C15）、30 t·hm-2（C30）、45 t·hm-2（C45）及秸秆还田（SNPK）的土壤进行温室气体（CO2、CH4和N2O）通量的原位观测，并估算生长季CH4和N2O的综合增温潜势（GWP）与排放强度（GHGI）。结果表明：添加生物炭能够显著减少土壤CO2和N2O的排放量，并促进土壤对CH4的吸收作用。其中处理C15对CO2的减排效果最好，与对照相比CO2排放量降低21.16%。随着施入生物炭量的增加，生物炭对N2O排放的抑制作用不断增强，处理C45对减排效果最好，与对照相比N2O排放量降低86.25%。处理C15对土壤吸收CH4的促进效果最好，CH4吸收量增加56.62%；处理C45对CH4的排放有促进作用，使生长季土壤吸收CH4减少81.36%。SNPK对温室气体的减排作用接近处理C15。添加生物炭和秸秆还田对提高玉米产量和降低农田GWP与GHGI均有显著效果，施用生物炭及秸秆还田均有效提高了科尔沁地区的玉米产量，且玉米产量随着施入生物炭含量的增大而提升。从GWP上来看，施用15 t·hm-2生物炭对温室气体减排的整体效果最好。从GHGI上来看，施用生物炭及秸秆还田均具有一定的经济效益和减排意义，其中施用15 t·hm-2生物炭的综合效益最高。因此综合经济效益与环境因素，建议科尔沁地区农田在种植玉米时添加15 t·hm-2生物炭，如不具备购买生物炭条件，可以考虑秸秆还田来实现玉米增产与温室气体减排。
关键词:生物炭/
玉米/
农田/
温室气体/
秸秆还田/
干旱区
Abstract:Biochar refers to a kind of stable and carbon-rich solid matter, generally composed of biomass and fertilizers, such as litter and crop straw, which have been pyrolyzed and carbonized under high temperatures in either a completely anaerobic or partially anoxic state. To explore the effects of biochar and straw returning on the greenhouse gas fluxes of corn fields in arid areas, an experiment was conducted on a corn field in the Horqin District, Inner Mongolia. A static chamber-gas chromatography (GC) technique was used to conduct in situ observations on greenhouse gas (CO2, CH4, and N2O) fluxes under different experimental treatments. These treatments included different application rates of biochar:0 (CK), 15 (C15), 30 (C30), and 45 t·hm-2 (C45); and straw returning (SNPK). For the experiments, the global warming potential (GWP) and greenhouse gas intensity (GHGI) during the growing season were estimated. The results showed that the addition of biochar could significantly reduce the soil CO2 and N2O emissions. During the growing season, the CO2 fluxes in the C15, C30, C45, and SNPK treatments decreased by 21.16%, 14.34%, 17.02%, and 19.93%, respectively. Among these treatments, C15 exhibited the best emission reduction effect. Compared with CK, the N2O fluxes of C15, C30, C45, and SNPK reduced by 24.42%, 56.83%, 86.25%, and 28.28%, respectively. With the increase in biochar rates, the inhibition effect on N2O emissions increased. Among the treatments, C45 provided the greatest reduction in emissions. Appropriate addition of biochar could promote the soil to absorb CH4. Compared with CK, the soil CH4 absorption of C15, C30, and SNPK increased by 56.62%, 32.05%, and 40.35%, respectively. The CH4 absorption of C45 decreased by 81.36% compared with CK. Excessive biochar could cause less CH4 absorption in the soil. There was a positive correlation between soil CO2 flux, temperature, and moisture during the growing season. The CH4 and N2O fluxes of CK, C15, and SNPK were significantly correlated with the soil temperature and moisture during the growing season. However, the CH4 and N2O fluxes of C30 and C45 did not exhibit a significant correlation with the soil temperature or moisture during the growing season. The addition of biochar and straw returning to the field had a significant effect on increasing the corn yield and reducing the GWP and GHGI in the farmlands. Biochar and straw returning both effectively increased the corn yield in the Horqin District. The corn yield increased as the amount of biochar increased. From the perspective of the GWP, a biochar rate of 15 t·hm-2 had the best overall effect on reducing greenhouse gas emissions, similar to the SNPK treatment. From the perspective of the GHGI, biochar and straw returning had certain economic benefits and significant reducing-effects of greenhouse gas emissions. Among the different treatments investigated, 15 t·hm-2 of biochar had the highest comprehensive benefits, and the C45 and SNPK treatments were slightly inferior to C15, but higher than C30. Therefore, from the perspectives of comprehensive economic benefits and environmental factors, it was suggested that 15 t·hm-2 of biochar should be added to the farmlands in Horqin when growing corn. If biochar was not available, straw returning can also be considered to achieve an increase in corn yields and decrease in greenhouse gas emissions.
Key words:Biochar/
Corn/
Farmland/
Greenhouse gas/
Straw returning/
Arid region
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