| Global warming is a very important environmental issue today, and farmland ecosystem plays a vital role in the global greenhouse gases budget, which have been consernd by scholars of all contries extensively. Field experiments including two soybean growing season and one winter-wheat growing season were adopted. And the entire experimental field was divided into four equal-area sub-blocks which differ from each other only in tillage systems which are no-tillage with no straw cover (NT), no-tillage with straw cover (NTS), conventional tillage (T) and conventional tillage with straw cover (TS). To investigate the influence of conservation tillage on CO2and N2O emission from farmland ecosystem, and CO2and N2O emission fluxes from soil and soil-crop system were analyzed by static chamber-gas chromatography method. Furthermore, this study will provide the base to evaluate the ecological effect of conservation tillage objectively, as well as to estimate the regional farmland greenhouse gas emission and its’ long term tendency in farmland ecosystem under conservation tillage. Results indicated that:Every treatment of conservation tillage, NT, NTS, and TS compared with conventional tillage (T), did not change the seasonal pattern of CO2and N2O emission fluxes from soil-winter wheat system. In the respect of CO2emission fluxes, NT significantly declined mean CO2emission fluxes (MCEF) by36.45%(p=0.041) during jointing-booting stage, however, NTS and TS had no significant difference (p>0.05) in MCEF. In the respect of N2O emission fluxes, none of NT, NTS and TS had significant difference (p>0.05) compared with T in mean N2O emission fluxes (MNEF).Every treatment of conservation tillage, NT, NTS, and TS compared with conventional tillage (T), did not change the seasonal pattern of CO2and N2O emission fluxes from soil-soybean system. In the respect of CO2emission fluxes, NT significantly declined MCEF by28.82%(p=0.043) during pod filling-maturity stage, NTS significantly raised MCEF by28.04%(p=0.045) during flowering-pod setting stage. There was no significant difference (p>0.05) between T and TS in MCEF. In the respect of N2O emission fluxes, none of NT, NTS and TS had significant difference (p>0.05) compared with T in MNEF.Every treatment of conservation tillage, NT, NTS, and TS compared with conventional tillage (T), did not change the seasonal pattern of CO2and N2O emission fluxes from soil. In the respect of CO2emission fluxes, none of NT, NTS and TS had significant difference (p>0.05) compared with T in MCEF. In the respect of N2O emission fluxes, NT significantly declined MCEF by31.64%(p=0.039), however, NTS and TS had no significant difference (p>0.05) in MCEF.An obvious diurnal variation of CO2emission fluxes was observed in soil-winter wheat system, soil-soybean system and soil, which did not changed by every treatment of conservation tillage, NT, NTS, and TS. And N2O emission fluxes showed regular or random diurnal variation from soil-winter wheat system, soil soybean system and soil. |
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