| 英文摘要: |
A field experiment was conducted to examine the influences of 5-year no tillage without straw retaining on soil organic carbon (SOC) and carbon dioxide (CO2) emissions from Mollisols, and to relate soil CO2 effluxes to variations in soil temperature and moisture. A closed-chamber method was used to determine CO2 efflux during the maize growing season in 2011. Our results showed no remarkable increase (P>0.05) in SOC for no tillage without straw retaining (NT), although NT practice decreased cumulative CO2 emission during the growing season by 30% (P<0.05) compared with conventional tillage (CT). Annual soil CO2 emissions were estimated at 13.34 and 9.39 Mg CO2 ha(-1) for CT and NT, respectively. The amount of annual lost C through CO2 emission from NT soils could be roughly replenished by incorporation of maize straw. The log-transformed multiple regression model [log(f) = a + b T + c log(W)] including both soil temperature and moisture was established, which accounted for 68 and 74% of the season variations in soil CO2 effluxes in NT and CT, respectively (both P<0.01). The temperature sensitivity of soil respiration was 2.39-2.75 in CT, which was higher than 2.01-2.34 in NT; soil respiration was more sensitive t o soil temperature at 10 cm than at 5 cm depth. Compared with CT, NT also decreased cumulative N2O emissions by 50% and thus total global warming potential of CO2 and N2O emissions. Results suggest that, considering C sequestration and global warming effect, the practice of no tillage without straw retaining is feasible in Mollisols in northeast China. |
