Effects Of Different Tillage Measures On Greenhouse Gases Emission In Pea-wheat Double Sequence Rotation Fields

Based on long-term conservation tillage experiment in Lijiabu Town of Dingxi City conducted by Gansu Agricultural University, taking conventional tillage with no straw (T), no-tillage with no straw mulching (NT), conventional tillage with straw mulching (TS) and no-tillage with straw mulching (NTS) four tillage treatments as the research object, using carbon dioxide analyzer and static chamber-gas chromatographic techniques continuously measured the emission fluxes of CO2, N2O and CH4in pea-wheat double sequence rotation fields under different tillage treatments during2011and discussed the effects of environmental factors on greenhouse gas emissions. The results showed that:1. Compared with other treatments, NTS and NT could significantly reduce CO2emissions of the farmland soil. In Wâ†'Pâ†'W sequence, the annual average CO2fluxes under NTS and TS treatment were significantly higher than T and NT treatment, CO2average flux under different treatment were NTS>TS>T>NT, the highest was NTS, the value was0.1149μmol·m-2s-1, the lowest was NT, the value was0.0898μmnol·m-2·s-1; In Wâ†'Pâ†'W sequence, the annual average CO2fluxes under T and TS treatment were significantly higher than NTS and NT treatment, CO2average flux under different treatments were TS>T>NTS>NT, the highest was TS, the value was0.1192μmnol·m-2·s-1, the lowest was NT, the value was0.1076μmnol·m-2·s-1.2. Fields with pea-wheat double sequence rotation were sources of atmospheric N2O under different treatment during entire determination period, and high N2O emissions were mainly concentrated in the crop growing period. In Wâ†'Pâ†'W sequence, the annual average N2O flux under different treatment were T>TS>NTS>NT, and the differences among the four treatments was not significant, the highest was T, the value was0.0591mg·m-2·h-1, the lowest was NT, the value was0.0465mg·m-2·h-1; In Wâ†'Pâ†'W sequence, the annual average N2O flux under different treatment were T>NT>NTS>TS, the highest was T, the value was0.0681mg·m-2·h-1, the lowest was TS, the value was0.0475mg·m-2·h-1. In two rotation sequences, TS, NTS and NT could significantly decrease the N2O emissions. Compared with Wâ†'Pâ†'W sequence, besides TS, average N2O flux and N2O emission under the other three treatments in Wâ†'Pâ†'W sequence were higher than Wâ†'Pâ†'W sequence. 3. Fields with pea-wheat double sequence rotation were sink of atmospheric CH4under different treatment during entire determination period. TS, NT and NTS three conservation tillage measures significantly increased the absorption of CH4, effectively reduced CH4emissions. In Wâ†'Pâ†'W sequence, the annual average CH4flux under different treatment were NT>NTS>TS>T, the highest was NT, the value was0.058mg·m-2·h-1, the lowest was T, the value was0.035mg·m-2·h-1; In Wâ†'Pâ†'W sequence, the annual average CH4flux under different treatment were TS>NT>NTS>T, the highest was TS, the value was0.0661mg·m-2·h-1, the lowest was T, the value was0.0463mg·m-2·h-1.4. The fluxes of CO2and N2O were significant related to soil temperature at different depths in fields with pea-wheat double sequence rotation under different treatment during entire determination period. The fluxes of CO2and N2O were extremely significant related to topsoil temperature, soil temperature at the depth of5cm, and were significant related to soil temperature at the depth of10cm. The fluxes of CH4showed negative correlations with soil temperature at different depths.5. The fluxes of CO2and CH4were significant related to soil water content at different soil layers in fields with pea-wheat double sequence rotation under different treatment during entire determination period. The fluxes of CO2and CH4were significant related to soil water content at the layer of0-5cm,5-10cm, and were negative related to soil water content at the layer of10-30cm. The fluxes of N2O showed negative correlations with soil water content at different soil layers.6. Two rotation sequences led to the most CO2emission and the highest GWP of CO2. In Wâ†'Pâ†'W sequence, the comprehensive GWP of CO2, N2O and CH4emissions under different treatment showed TS>T>NTS>NT, the contribution of greenhouse effect mainly attributed to TS treatment and little attributed to NT treatment. In Wâ†'Pâ†'W sequence, the comprehensive GWP of T treatment was the highest, the contribution of greenhouse effect mainly attributed to T treatment and little attributed to TS treatment.