秸秆不同还田模式对玉米田温室气体排放和碳固定的影响

Effects of Different Return Modes of Wheat Straws on Greenhouse Gas Emissions and Carbon Sequestration of Maize Fields

为了探讨小麦秸秆不同还田模式对玉米田温室气体排放和碳固定的影响,通过田间试验,测定了秸秆不同还田方式下玉米生长季温室气体(CO2、N2O和CH4)的排放量和碳固定量,结果表明:秸秆不同还田模式对温室气体排放量影响不同,在玉米生长季,CO2和N2O累计排放量表现为秸秆过腹还田(CGS)>秸秆直接还田(CS)>秸秆不还田(CK)>秸秆-菌渣还田(CMS),CH4的累计吸收量表现为CGS>CK>CMS>CS,且不同处理间差异显著(P<0.05);秸秆不同还田模式也影响土壤和植物的碳储量,耕层土壤有机碳储量表现为CGS>CMS>CS>CK,且不同处理间差异显著(P<0.05),植株、籽粒的固碳量表现为CGS>CS>CMS>CK,但不同处理间差异不显著(P>0.05)。和CK相比,在CS、CGS和CMS模式下,玉米田对全球变暖的减缓效应均增加,但增加量不同,表现为CGS>CMS>CS>CK,既秸秆过腹还田模式下玉米田对全球变暖的减缓效应最大,其次是秸秆-菌渣还田模式,之后是秸秆直接还田模式。在秸秆过腹还田模式下,玉米田对全球变暖的减缓效应为22 493.83 kg CO2·hm-2,分别比CK、CS和CMS模式下玉米田对全球变暖的减缓效应增加24.2%、18.7%和1.6%。从减缓全球变暖的角度,推荐秸秆过腹还田模式,该模式也有利于形成粮食-秸秆-饲料-牲畜-肥料-粮食的良性循环,实现农田的固碳、减排。

Returning crop residues to soil could improve soil fertility and increase crop yields, but it may also casue elevated greenhouse gas emissions. In this study, an experiment was conducted to assess the effects of different modes of wheat straw return on CO2, N2 O and CH4 emissions and carbon sequestration in maize fields during maize growing season. The modes of wheat straw return included chopped straw direct return(CS), cow-digested straw return(CGS), and mushroom-cultivated straw return(CMS). The cumulative emissions of CO2 and N2O were both in order of CGS>CS>non-straw return(CK)>CMS, while the cumulative CH4 absorption followed the sequence of CGS>CK>CMS >CS. Soil organic carbon content decreased in order of CGS >CMS >CS >CK, with significant difference between different treatments(P<0.05). However, carbon storage in plants and grains declined in the sequence of CGS>CS>CMS>CK, with no significant difference between different treatments(P>0.05). Compared to CK, CS, CGS, and CMS all mitigated the global warming effects of maize fields. The postlivestock digestion straw return mode could be recommended from in order of CGS>CMS>CS>CK. The mitigating benefit of global warming by CGS was 22 493.83 kg CO2·hm-2, 24.2%, 18.7%, and 1.6% greater than that of CK, CS, and CMS, respectively. Therefore, the perspective of decreasing the global warming, and it also forms benign cycle of food-straw-cattle manure-fertilizer-food.