旱区灌溉棉田土壤呼吸昼夜变化特征及其与土壤温度的关系

本试验以裸地为对照,通过对土壤剖面CO2浓度的监测,研究了旱区灌溉棉田土壤呼吸的昼夜变化规律及其与土壤温度的关系。主要结果如下:(1)土壤及根际呼吸均呈"V"型昼夜变化特征,最小值出现在16∶00~17∶00之间,而土壤微生物呼吸昼夜变化趋势与之相反;(2)土壤微生物呼吸产生的CO2通量在土壤升温阶段略高于降温阶段,相对的,根际呼吸在土壤升温阶段产生的CO2通量低于降温阶段,并形成一个明显的逆时针圆圈;(3)棉花根际呼吸对土壤呼吸的平均贡献率为47%。以上结果说明,在建立土壤呼吸与土壤温度相关关系模型的过程中,需要区分根际呼吸和土壤微生物呼吸,充分考虑土壤温度变化对土壤呼吸各组分影响的差异性。

Characteristics of diurnal variation of soil respiration and its relationship with soil temperature of cotton fields in arid irrigated regions

With bare land as CK,a field experiment was conducted to investigate the characteristics of diurnal variation of soil respiration and its relationship with soil temperature of cotton fields in arid irrigated regions by monitoring CO2 content of soil profile.The results indicated that(1) Soil and rhizosphere respiration showed a "V"-type feature of diurnal variation,the minimum value occurred between 16∶00～17∶00,while the trend of soil microbial respiration was opposite;(2) Soil microbial respiration at the period of soil temperature increasing was higher than that at the period of soil temperatures decreasing.However,rhizosphere respiration displayed an opposite result which formed an obvious counterclockwise hysteresis loop;(3) The contribution percentage of rhizosphere respiration to soil respiration was 47%.The results suggested that differentiating between rhizosphere respiration and soil microbial respiration was a very important step to establish the model of soil respiration and soil temperature correlation,and the differences of the impacts of soil temperature on soil respiration should be considered.