Effects of straw mulching on greenhouse gas intensity under on-tillage conditions

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.