玉米秸秆不同还田方式下麦田温室气体排放特征

为了探讨玉米秸秆不同还田方式对麦田温室气体排放的影响,通过田间试验,设玉米秸秆不还田(CK)、玉米秸秆直接还田(CS)、玉米秸秆过腹还田(CGS)和玉米秸秆转化为食用菌基质,出菇后菌渣还田(CMS)4个处理,利用静态箱-气相色谱法测定了玉米秸秆不同还田方式下,麦田温室气体(CO_2、N_2O和CH_4)的排放特征。结果表明:玉米秸秆不同还田方式下,麦田温室气体通量均具有明显的季节变化,且排放量不同。在小麦生长季,CO_2和N_2O均表现为排放,其排放量为CKCGSCSCMS;甲烷表现为吸收,其吸收量为CSCGSCKCMS,且不同处理间差异显著(P0.05)。从温室气体综合增温潜势(GWP)来看,在20、100年和500年3个时间尺度上,仅玉米秸秆不同还田方式这一环节,GWP均表现为:CSCGSCKCMS,也就是说秸秆直接还田,显著增加麦田温室气体的全球增温潜势,其次是玉米秸秆过腹还田方式,而秸秆-菌渣还田则降低了麦田温室气体的全球增温潜势。从减少温室气体排放角度,推荐秸秆-菌渣还田方式。该研究结果可为秸秆合理利用和温室气体减排提供基础数据。

Characteristics of Greenhouse Gas Emissions from the Wheat Fields with Different Returning Methods of Maize Straws

In order to investigate the effect of different returning methods of maize straw on the greenhouse gas emissions from the wheat fields, we explored the greenhouse gas CO2, N2O and CH4 emissions from the wheat fields using static chamber-gas chromatograph technique from December 2013 to May 2014 . The experiments set four treatments including no maize straw returning(CK), direct maize straw returning directly(CS), maize straw-rumen-cattle dung returning(CGS)and maize straw-mushroom residue returning(CMS), and the four treatments were investigated under the same watering and fertilizing conditions. The results showed that the greenhouse gas emissions from the wheat fields all had distinct seasonal variations and the cumulative emissions of greenhouse gas emissions were different. During the maize growing season, the cumulative emissions of both CO2 and N2O were emitted and in the order of CK>CGS>CS>CMS while the cumulative absorptions of CH4 were in the order of CS>CGS>CK>CMS with the significant difference between different treatments(P<0.05). The global warming potential(GWP)of greenhouse gases in three time periods(20 years, 100 years and 500 years)were all in the order of CS>CGS>CK>CMS under the different returning methods of maize straw, which indicated that direct straw returning could significantly increase the global warming potential of greenhouse gases from the wheat field, followed by CGS while the straw-mushroom residue returning (CMS)could decrease the global warming potential of greenhouse gases from the wheat field. The method of straw-mushroom residue returning should be recommended from the viewpoint of reducing GWP of the greenhouse gas. In all, our study could provide the scientific foundation for the efficiency straw recycle and reducing greenhouse gas emission.