【作者】 张寒；

【导师】 胡正华；

【作者基本信息】 南京信息工程大学 ， 生态学， 2012， 硕士

【摘要】 全球变暖是当今重要的环境问题,农田生态系统在全球温室气体收支中占有重要地位,引起了国内外学者的广泛关注。本研究采用田间试验方法,进行不同耕作方式和秸秆管理处理,分别为免耕(NT, no-till with no straw cover),免耕+秸秆(NTS, no-till with straw cover),常规翻耕(T, conventional tillage),常规翻耕+秸秆(TS, conventional tillage with straw cover),开展了两个大豆生长季和一个冬小麦生长季的试验。采用静态箱-气相色谱法测定土壤及土壤-作物系统的CO2和N20排放通量,探讨保护性耕作对农田生态系统CO2和N20排放的影响。为全面的评价保护性耕作的生态效益,以及在保护性耕作大范围推广背景下预测区域农田生态系统温室气体排放趋势提供科学依据。结果表明：免耕(NT)、免耕+秸秆(NTS)和翻耕+秸秆(TS)与传统耕作(T)相比,都没有改变土壤-冬小麦系统CO2和N2O排放通量的季节性变化规律。从CO2排放通量来看,NT处理在拔节-孕穗期显著降低了土壤-冬小麦系统的CO2排放通量,降幅达36.45%(p=0.041),NTS.TS则无显著差异(p>0.05)。从N2O排放通量来看,NT.NTS以及TS与常规耕作T相比均无显著差异(p>0.05)。免耕(NT)、免耕+秸秆(NTS)和翻耕+秸秆(TS)与传统耕作(T)相比,都没有改变土壤-大豆系统CO2和N20排放通量的季节性变化规律。从CO2排放通量来看,NT处理在鼓粒-成熟期显著降低了土壤-大豆系统的CO2排放通量,降幅达28.82%(p=0.043),NTS则在开花-结荚期显著增加了土壤-大豆系统的CO2排放通量,增幅达28.04%(p=0.045),TS处理与常规耕作T相比无明显差异(p>0.05)。从N20排放通量来看,NT.NTS以及TS与常规耕作T相比均无显著差异(p>0.05)。免耕(NT)、免耕+秸秆(NTS)和翻耕+秸秆(TS)与传统耕作(T)相比,都没有改变土壤CO2和N20排放通量的季节性变化规律。从CO2排放通量来看,NT、NTS以及TS均不同程度降低了土壤CO2排放通量,但差异不显著(p>0.05)。在N20排放通量方面,NT显著降低了土壤的N20排放通量,降幅达31.64%(p=0.039),NTS.TS与常规耕作T相比则无显著差异(p>0.05)。土壤-冬小麦系统、土壤-大豆系统以及土壤的CO2排放通量有着较明显的日变化规律,保护性耕作各处理免耕(NT)、免耕+秸秆(NTS)和翻耕+秸秆(TS)与传统耕作(T)相比都没有改变这一规律。土壤-冬小麦系统、土壤-大豆系统以及土壤的N20排放呈规律性和随机性排放两种,保护性耕作各处理同样没有改变这一规律。更多还原

【Abstract】 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.更多还原