双季稻区冬季覆盖作物残茬还田对稻田甲烷和氧化亚氮排放的影响

Effects of Straw Recycling of Winter Covering Crop on Methane and Nitrous Oxide Emissions in Paddy Field

研究冬季不同覆盖作物还田后稻田的甲烷(CH4)和氧化亚氮(N2O)排放特征,对合理利用冬闲稻田,发展冬季覆盖作物,以及科学评价不同种植模式具有重要意义。本研究采用静态箱-气相色谱法,对冬季不同覆盖作物处理(免耕直播黑麦草-双季稻、免耕直播紫云英-双季稻、翻耕移栽油菜-双季稻、翻耕稻草覆盖马铃薯-双季稻和冬闲-双季稻)的稻田进行监测,以分析不同覆盖作物残茬还田对稻田CH4和N2O排放的影响。结果表明,冬季覆盖作物还田后,各处理早、晚稻田CH4排放量均明显高于冬闲-双季稻(对照)。早稻田CH4排放量最高的为翻耕稻草覆盖马铃薯-双季稻和免耕直播黑麦草-双季稻,分别达20.713gm-2和16.068gm-2;晚稻田CH4排放量最高的为翻耕稻草覆盖马铃薯-双季稻和翻耕移栽油菜-双季稻,分别为60.421gm-2和48.666gm-2。各处理早、晚稻田N2O总排放量均显著高于冬闲-双季稻,免耕直播黑麦草-双季稻、免耕直播紫云英-双季稻、翻耕移栽油菜-双季稻和翻耕稻草覆盖马铃薯-双季稻处理的早稻田N2O总排放量分别比对照增加265.00%、320.00%、275.00%和65.00%,晚稻田分别比对照增加157.89%、113.16%、134.21%和42.11%。稻田CH4和N2O综合温室效应总和表现为翻耕稻草覆盖马铃薯-双季稻>翻耕移栽油菜-双季稻>免耕直播黑麦草-双季稻>免耕直播紫云英-双季稻>冬闲-双季稻,冬季覆盖作物还田明显提高稻田CH4和N2O排放。

To learn the characteristics of CH4 and N2O emissions from paddy fields with different double rice cropping patterns will significantly benefit the exploitation of winter fallow paddy with covering crops and the assessment of rice cropping patterns.Therefore,the static chamber-GC technique with manual method was used to determine the effects of double rice cropping systems with different winter covering crops on the emissions of CH4 and N2O.These systems included ryegrass with no-tillage and double rice cropping（T1）,Chinese milk vetch with no-tillage and double rice cropping（T2）,rape seed with tillage and double rice cropping（T3）,potato with straw mulching and tillage and double rice cropping（T4） and fallow and double rice cropping（CK）.The results showed that straw recycling of winter crops significantly increased the emissions of CH4 both during the early and later rice growing seasons than the CK.The T4 and T1 treatments had the largest CH4 emissions during the early rice growing season with 20.713 and 16.068 g m^-2,respectively,while the T4 and T3 treatments had the largest CH4 emission during the later rice growing season with 60.421 and 48.666 g m^-2,respectively.The four treatments with winter covering crops also had larger N2O emissions both during the early and later rice growing seasons than the CK.N2O emissions during the early rice growing season under T1,T2,T3,and T4 treatments were increased by 265.00%,320.00%,275.00%,and 65.00%,and during the later rice growing season by 157.89%,113.16%,134.21%,and 42.11%,respectively,compared with the CK.Meanwhile,the global warming potentials（GWPs） from paddy fields with different cropping patterns were T4〉T3〉T1〉T2〉CK.As a result,straw recycling of winter covering crops will significantly increase the emissions of CH4 and N2O from paddy field under double rice cropping systems.