水旱轮作土壤-小麦系统CO2排放及其影响因素

利用静态箱/气相色谱法对川中丘陵区水旱轮作区的小麦进行全生长季CO2排放观测.结果表明,(1)土壤-小麦系统的CO2排放通量存在着明显的日变化.凌晨400～600排放量最低,随着温度的升高,CO2的排放量逐渐增大,在午后100～300达到峰值.分析表明,气温和地表温度与土壤-小麦系统CO2排放通量之间存在显著的相关关系.(2)土壤-小麦系统CO2排放都有明显的季节变化.分析表明,小麦生物量和气温与土壤-小麦系统CO2排放季节变化之间存在显著的相关关系.(3)在小麦各个生育期中,CO2平均排放通量常规处理>无氮处理>空白>裸地.水旱轮作区小麦常规处理、无氮处理、空白点和裸地的CO2排放通量的平均值分别为574.51、362.23、239.91、129.47 mg/(m2·h).在小麦的各个生育期中,RH、RAR和RAS对土壤-小麦系统CO2排放的贡献率分别为20%、20%和60%.

CO2 emission from soil-wheat system in a paddy-dryland rotation area in purple soil and its influence factors

CO2 emission from soil-wheat system in a paddy field-dryland rotation area in purple soil were measured by static chamber-gas chromatographic techniques in the central Sichuan Basin. Results showed: (1) daily CO2 emission from soil-wheat system varified remarkably. The emission of CO2 was at the lowest stage between 4:00 and 6:00 before dawn, and it was crescent and reached peak value between 1:00 and 3:00 in the afternoon with the rising of temperature. Analyses showed that there were significant relation between CO2 emission flux and the air temperature, surface ground temperature. (2) CO2 emission from soil-wheat system varified remarkably seasonaly. Analyses showed that there were significant relation between CO2 emission flux and wheat biomass and air temperature. (3) CO2 emitted at follow sequence treatment in wheat bearing stage: ordinary planting treatment > no nitrogen fertilizer> no plant>bare land. Average flux of CO2 emission from ordinary planting treatment, no nitrogen fertilizer, no plant and bare land treatment were 574.51, 362.23, 239.91 and 129.47 mg/(m2h) , respectively. Contribution ratio of RH, RAR and RAS to CO2 emission from soil-wheat system were 20%, 20% and 60%, respectively.