稻秆还田方式对稻麦轮作农田CH_4和N_2O排放的影响

Impact of rice straw return methods on CH_4 and N_2O emissions across a rice-wheat rotation

[目的]本研究旨在明确秸秆不同还田方式对稻麦轮作农田温室气体排放的影响,为稻麦轮作农田选择合理的秸秆还田方式提供参考。[方法]试验设置了稻秆集中沟埋还田(RD)、旋耕还田(RR)、表层覆盖还田(RC)和稻秆不还田(CK)4个处理,采用静态箱-气相色谱法监测了2014—2015稻麦轮作年农田CH_4和N_2O排放情况。[结果]同CK相比,稻秆还田增加了稻季CH_4排放,且RC处理下的CH_4累积排放量显著高于其他处理,麦季CH_4排放整体保持较低水平。同CK相比,稻秆不同还田方式增加了稻麦两季N_2O排放,但稻季各处理差异不显著,麦季RC处理下的N_2O累积排放量显著高于CK,但不同还田方式间差异不显著。3种还田方式下,RC处理的周年CH_4和N_2O排放量均为最大,RD处理最小,且RD处理的增温潜势也为最小。稻秆还田增加了稻麦轮作周年作物产量,与CK相比,RR和RD分别增加了6.70%和9.75%。与RC和RR相比,RD处理下农田温室气体排放强度分别降低了48.13%和3.38%。[结论]稻秆集中沟埋还田是稻麦轮作农田较为适宜的还田方式。

[ Objectives ] The purpose of this study was to determine the effects of different straw returning methods on the greenhouse gas emission, and thus, to provide reference for selecting a reasonable straw returning methods in rice-wheat rotation system. [ Methods] A field experiment was conducted during 2014-2015 to investigate the effects of the different ways of rice straw returning on greenhouse gas emission by using the method of static chamber-gas chromatographic techniques in rice-wheat rotation system. Four treatments （i.e. without rice straw returning, CK;rice straw covered returning, RC ; rice straw rotary returning, RR; rice straw concentrated ditch-buried returning, RD）were implemented in this experiment. [ Results ] Results showed that compared with CK, rice straw returning increased CH4 emission in rice season, and RC had significantly higher CH4 emission than other treatments. While CH4 emissions remained in the lower level in wheat season. Compared to CK, rice straw returning increased N20 emission in both rice and wheat season, but there was no significant difference between all treatments in rice season. N20 emission under RC was significantly higher than CK,but no significant difference between the three straw returning methods. Among the three straw returning methods, RC had the highest annual CH4 and N20 emissions, and RD had the lowest, moreover, RD had the least annual global warming potential. Rice straw returning could improve annual crop yield. Compared with CK, RR and RD could increase 6.70% and 9.75%, respectively. Compared with RC and RR, RD could decrease greenhouse gas emissions intensity by 48.13% and 3.38%, respectively. [ Conclusions ] Therefore,rice straw concentrated ditch-buried returning was a suitable method in rice-wheat rotation system. Keywords ： rice straw; straw returning method ; rice-wheat rotation ; greenhouse gases