Abstract:
Different tillage methods and crop rotations were experimented in Lijiabao Town of Dingxi City, Gansu Province and soil carbon dioxide (CO
2), methane (CH
4) and nitrous oxide (N
2O) fluxes measured using carbon dioxide analyzer and static chamber-gas chromatographic techniques. Analysis of the four tillage methods tillage without straw or plastic film mulching (T), no-tillage without straw or plastic film mulching (NT), no-tillage with straw mulching (NTS) and tillage with straw mulching (TS) showed that soils with spring wheat and pea were sources of atmospheric CO
2 and N
2O, sink of CH
4 during crop growth seasons. In spring wheat fields, the mean values of soil CO
2 flux (μmol·m
-2·s
-1) were 0.203 6, 0.221 2, 0.241 8 and 0.224 9 for T, NT, NTS and TS treatments, respectively. The mean values of soil CH
4 flux (mg·m
-2·h
-1) were -0.041 6, -0.078 0, -0.081 8 and -0.053 7 and those of soil N
2O flux (mg·m
-2·h
-1) were 0.089 1, 0.069 2, 0.046 1 and 0.065 6 for T, NT, NTS and TS treatments, respectively. In pea field, the mean values of soil CO
2 flux (μmol·m
-2·s
-1) were 0.273 6, 0.261 6, 0.218 1 and 0.236 0 for T, NT, NTS and TS treatments, respectively. The mean values of soil CH
4 flux (mg·m
-2·h
-1) were -0.055 0, -0.073 7, -0.066 2 and -0.054 5 and those for soil N
2O flux (mg·m
-2·h
-1) were 0.123 4, 0.084 7, 0.080 6 and 0.035 0, respectively. Compared with T, NT and TS, NTS retarded CO
2 and N
2O emission and enhanced CH
4 assimilation. Based on the study, NT, NTS and TS conservation tillage methods were efficient for retarding greenhouse gas emission. CO
2 fluxes increased with increasing soil moisture and temperature in spring wheat field, and CH
4 uptake fluxes increased with increasing soil moisture, but reduced with increasing soil temperature. A significant positive correlation was noted between CO
2 flux and soil moisture in pea field. Similarly, a significant positive correlation was observed between N
2O emission and soil temperature in pea and spring wheat fields.