耕作措施对双季稻田CH_4与N_2O排放的影响

Tillage effects on CH_4 and N_2O emission from double cropping paddy field

随着全球气温的不断升高,温室气体减排成为研究的热点。该文旨在研究不同耕作措施下双季稻田CH4及N2O排放特征及其消长关系,为稻田温室气体减排及土壤固碳潜力评价提供依据。试验在湖南省宁乡县进行,通过静态箱法测定翻耕秸秆还田(CT)、旋耕秸秆还田(RT)、免耕秸秆还田(NT)的稻田CH4及N2O排放。结果表明:CH4排放主要来自于晚稻田,翻耕、旋耕和免耕晚稻田CH4排放分别占研究时段CH4排放的69%,67%,73%;各处理冬闲季CH4排放均不到研究时段排放量1%,冬闲CH4排放量为RT>CT>NT,差异显著;N2O排放时间变异性较大,早稻稻田N2O排放量为RT>NT>CT,晚稻稻田N2O排放量为NT>RT>CT,冬闲期各处理稻田N2O均为负排放;从研究时段排放量分析,翻耕秸秆还田有利于减少N2O排放,免耕秸秆还田有利于减少CH4排放;CH4与N2O排放呈显著负相关,冬闲季稻田CH4与N2O排放相关性不显著。总之,NT减少了CH4排放,虽N2O排放略有增加,但CH4与N2O引发的综合温室效应有所减弱。

Greenhouse gas emission is becoming a very important issue with the continuous increasing in the global temperature.In order to evaluate carbon sequestration potential of paddy and reducing emission of greenhouse gas, tillage effects on CH4 and N2O emissions from paddy soil and the trade-off relationship between CH4 and N2O were explored.The closed chamber method was used to measure the CH4 and N2O emission from the paddy field with the treatments of conventional tillage（CT）,rotary tillage（RT）,no-tillage（NT）at Ningxiang County,Hunan Province.The results show as following.1）CH4 emission mainly comes from the late rice paddy,which accounted for 69%,67%,73% of the studied period under CT,RT and NT,respectively;2）CH4 emission of all treatments attributed to less than 1%in the winter-fallow season,while the differences of the emission among three treatments are significant with RT〉CT〉 NT;3）N2O emission shows highly temporal variability that N2O emission in early rice paddy is RT〉NT〉CT,while in late rice paddy is NT〉RT〉CT,and the N2O is absorbed in winter-fallow season;4）CT is beneficial to decreasing N2O emission during the studied period,while NT is beneficial to decreasing CH4 emission;5）During the studied period, correlation between CH4 and N2O shows negative significantly,but the correlation between CH4 and N2O in winter-fallow season is not significant.In general,though increasing N2O emission appreciably,NT is beneficial to decreasing CH4 emission,and the comprehensive greenhouse effect of N2O and CH4 is also decreased.