Abstract:
This study analyzed the effects of different tillage conditions on greenhouse gas emissions of double sequence pea-wheat rotation fields during 2011. Three greenhouse gases (CO
2, N
2O and CH
4) emission were investigated under four tillage types conventional tillage without straw mulching (T), no-tillage without straw mulching (NT), conventional tillage with straw mulching (TS) and no-tillage with straw mulching (NTS). The carbon dioxide analyzer and static chamber-gas chromatographic techniques were used to continuously measure and analyze the greenhouse gases fluxes. The results showed that double sequence pea-wheat rotation fields served not only as source of atmospheric CO
2, N
2O, but also as sink of atmospheric CH
4. Compared with T, NT retarded CO
2 emission. The three conservation tillage methods of NTS, NT and TS reduced N
2O emission but significantly increased CH
4 absorption. CO
2 and N
2O fluxes were significantly correlated with topsoil temperature (
R2 = 0.92
** and 0.89
**), soil temperature at the 5 cm soil depth (
R2 = 0.95
** and 0.91
**) and soil temperature at the 10 cm soil depth (
R2 = 0.77
* and 0.62
*). CH
4 fluxes were uncorrelated with soil temperature at different soil depths. The correlation coefficients between CO
2 and soil water content, and CH
4 and soil water content at 0~5 cm soil layer were 0.69
* and 0.72
*, respectively. The correlation coefficient between CO
2 and soil water content at the 5~10 cm soil layer was 0.77
* and that between CH
4 and soil water content at the 5~10 cm soil layer was 0.64
*. CO
2, CH
4 fluxes were positively correlated with soil water content at the 10~30 cm soil layer. N
2O fluxes showed negative correlations with soil water content at different soil layers. The calculated global warming potential of the three greenhouse gases under the different tillage conditions showed that NT limited greenhouse gas flux, thereby reducing greenhouse effect.