玉米农田土壤呼吸与环境因子的关系研究

Studies on soil respiration and its relation with environmental factors in a Maize (Zea mays L.) field in Taiyuan Basin

采用LICOR-6400便携式光合作用仪连接6400-09土壤叶室,于2005年1月至12月对太原盆地夏玉米农田的土壤呼吸进行了测定,同时测定了土壤温度和水分,目的是了解玉米农田土壤呼吸的日变化及季节变化规律及其与环境因子的关系。结果表明:夏玉米农田土壤呼吸速率具有比较明显的日变化,晚间维持在较低水平,最低值在凌晨5:00左右,随后开始上升,最大值一般在11:00-15:00之间;同时土壤呼吸速率也具有较明显的季节变化,冬春季较低,盛夏秋初较高,最大值出现在8月,最低值出现在2月。土壤呼吸速率与0-10cm的土壤温度关系显著,剔除土壤水分胁迫时的测定数据后,土壤温度可以解释土壤呼吸变化的29%(直线函数)、41%(指数函数)、44%(Lloyd&Taylor函数);标准化前、后土壤呼吸与土壤水分均呈极显著相关(p<0.01);剔除水分胁迫后的Q10为2.32,R10为2.23(指数方程)、2.67molm-2s-1(Lloyd&Taylor方程)。土壤温度和土壤水分结合在一起进行土壤呼吸预测,可以解释土壤呼吸季节变化的48-52%。玉米农田的年土壤呼吸总量为1.476kgCm-2。

Using an infrared gas analyzer （IRGA） attaching a 6400 -09 chamber, soil CO2 efflux rate was measured in a maize field located in Taiyuan basin from January to December 2005. The temperature （Ts） at 10 cm depth and the soil water content （Ws） over top 10 cm were also measured at the same time. The aim was to understand the diurnal and temporal changes of soil respiration and its responses to soil temperature and soil water content. The results showed that soil respiration rate （Rs） of maize had an asymmetric diurnal pattern, with the minimum appearing about 5：00 and the maximum around 11：00- 15：00. The seasonal change of Rs in the maize land was significant, with the higher values in August and the lower values in February. The functional relationships of Rs to Ts could be described by linear, exponential or Lloyd ＆ Taylor equation. The coefficients of determination R^2 of T to SR were 29 % for linear equation, 41% for exponential equation and 44% for Lloyd ＆ Taylor equation when the drought - affected data were excluded. The relation of soil respiration and soil water content is very notable （p 〈 0.01 ）. For all data sets, four two -variable equations including linear and non - linear ones could be used to model relationships of Rs to both Ts and Ws together, with the R^2 ranging from a minimum of 0.48 to a maximum of 0.52. Based on daily - weighted monthly mean of Rs, the released annually cumulative CO2 amount was 1476 g Cm^-2 in 2005.