免耕条件下稻草还田方式对温室气体排放强度的影响

摘要

To investigate the effects of straw mulching on greenhouse gas intensity (GHGI) under the no tilling conditions, a two-year (2008-2009) observation of greenhouse gas emissions with different treatments of NWS (no till + no residue ), HN (no till + high stubble) and SN (no till + straw mulching) was conducted by using the static chamber- GC (gas chromatography) method. The results indicated that the two treatments of HN and SN at the same rate of straw mulching had no difference in rice yield and increased GHGI compared to the NWS treatment. The GHGI of SN was lower than that of HN, which indicated that the HN treatment enhanced the ability of GHGI transportation by rice aerenchyma. On a 20-year scale, the average GHGI of methane was 109 times and 14 times greater than nitrous oxide for early and late rice, respectively, while on a 20-year scale, the value was lower, but still was 35 times and 3.77 times. In conclusion, the GHGI of the double-rice field will be affected by different practices of retaining rice residue determined. Compared with the HN treatment, straw mulching (SN) will be a reasonable choice for straw mulching. This study provides references for the enhancement of carbon sequestration and mitigation of GHGI emissions in a double-rice field in the Central China Region.%为探讨免耕条件下的稻草高茬和覆盖还田对双季稻田温室气体排放强度( GHGI)的影响,该研究利用静态箱-气相色谱法,对免耕稻草不还田(NWS)、免耕高茬还田(HN)和免耕覆盖还田(SN)3处理稻田GHGI进行了连续2a的观测.结果表明,在各处理水稻产量差异不显著时,双季稻田的GHGI主要由温室气体排放量决定；在稻草用量相同的情况下,2种稻草还田方式均增加了稻田的GHGI,且高茬还田的增加幅度大于覆盖还田,说明高茬还田增强了温室气体通过水稻体内通气组织传输的能力.在20和100 a尺度上,甲烷的GHGI均远大于氧化亚氮,在20 a尺度上,早稻各处理甲烷的GHGI平均为N2O的109倍,晚稻为14倍,而在100 a尺度上,这个倍数有所下降,分别只有35倍和3.77倍,可见,减少甲烷排放是减缓稻田温室气体排放强度的首要目标.在等稻草量的前提下,相比留高茬还田,覆盖还田能有效控制稻田GHGI.该研究可为中国华中地区双季稻田碳增汇和温室气体减排研究提供参考.