不同耕作条件下豆麦双序列轮作农田土壤温室气体的排放及影响因素研究

Greenhouse gas emissions in double sequence pea-wheat rotation fields under different tillage conditions

为了研究耕作措施对双序列轮作农田土壤温室气体的排放及影响,采用CO2分析仪、静态箱气相色谱法在陇中黄土高原半干旱区对传统耕作不覆盖、免耕不覆盖、免耕秸秆覆盖和传统耕作＋秸秆还田4种耕作措施下豆麦双序列轮作农田土壤温室气体（CO2、N2O和CH4）的排放及影响因素进行了连续测定和分析。结果表明：测定期内4种耕作措施下农田土壤均表现为CO2源、N2O源和CH4净吸收汇;除传统耕作不覆盖措施,其他3种耕作措施不同程度地减少了2种轮作序列土壤的N2O排放通量,并显著增加了土壤对CH4的吸收。CO2和N2O的排放通量分别与地表、地下5 cm处、地下10 cm处的土壤温度呈极显著和显著正相关关系,相关系数分别为0.92^＊＊和0.89^＊＊、0.95^＊＊和0.91^＊＊、0.77^＊和0.62^＊;而CH4吸收通量与不同地层的温度之间无明显的相关关系;CO2和CH4的通量与0-5 cm、5-10 cm的土壤含水量均呈显著正相关关系,相关系数分别为0.69^＊和0.72^＊、0.77^＊和0.64^＊,而与10-30 cm土壤含水量无明显相关关系;N2O排放通量与各层次的土壤含水量之间均呈不显著负相关关系。对2种轮作序列各处理下土壤中排放的3种温室气体的增温潜势计算综合得出：4种耕作措施中,免耕不覆盖处理可相对减少土壤温室气体的排放量,进而降低温室效应。

This study analyzed the effects of different tillage conditions on greenhouse gas emissions of double sequence pea-wheat rotation fields during 2011.Three greenhouse gases（CO2,N2O and CH4） emission were investigated under four tillage types [conventional tillage without straw mulching（T）,no-tillage without straw mulching（NT）,conventional tillage with straw mulching（TS） and no-tillage with straw mulching（NTS）].The carbon dioxide analyzer and static chamber-gas chromatographic techniques were used to continuously measure and analyze the greenhouse gases fluxes.The results showed that double sequence pea-wheat rotation fields served not only as source of atmospheric CO2,N2O,but also as sink of atmospheric CH4.Compared with T,NT retarded CO2emission.The three conservation tillage methods of NTS,NT and TS reduced N2O emission but significantly increased CH4absorption.CO2 and N2O fluxes were significantly correlated with topsoil temperature（R2 = 0.92^＊＊and 0.89^＊＊）,soil temperature at the 5 cm soil depth（R2= 0.95^＊＊and 0.91^＊＊） and soil temperature at the 10 cm soil depth（R2 = 0.77^＊and 0.62^＊）.CH4 fluxes were uncorrelated with soil temperature at different soil depths.The correlation coefficients between CO2 and soil water content,and CH4 and soil water content at 0-5 cm soil layer were 0.69^＊and 0.72^＊,respectively.The correlation coefficient between CO2and soil water content at the 5-10 cm soil layer was 0.77^＊and that between CH4and soil water content at the 5-10 cm soil layer was 0.64^＊.CO2,CH4fluxes were positively correlated with soil water content at the 10-30 cm soil layer.N2O fluxes showed negative correlations with soil water content at different soil layers.The calculated global warming potential of the three greenhouse gases under the different tillage conditions showed that NT limited greenhouse gas flux,thereby reducing greenhouse effect.