节水灌溉与生物炭施用对稻田生态系统CO_(2)净通量日变化的影响

Effects of Water-saving Irrigation and Biochar Application on the Diurnal Variation of Net CO_(2) Flux in Paddy Field Ecosystem

为了揭示不同水碳管理对稻田生态系统-大气间CO_(2)交换的影响,基于田间试验,分析了不同水碳管理模式下稻田生态系统CO_(2)净通量日变化特征。结果表明:分蘖期、拔节孕穗期、乳熟期稻田生态系统CO_(2)净通量变化趋势均呈现U型特征,总体表现为白天吸收,夜晚排放,且各生育期的净吸收阶段与净排放阶段在时间上呈现一致性。随着生育期的推进,稻田生态系统白天CO_(2)净吸收时长及吸收量呈现先升高后降低趋势。除分蘖期高量生物炭处理降低了稻田生态系统白天CO_(2)净吸收通量外,生物炭施用增大了节水灌溉稻田生态系统白天CO_(2)净吸收通量与夜晚CO_(2)净排放通量。与不施用生物炭处理相比,2种生物炭情况下稻田生态系统白天与夜间CO_(2)净通量增加幅度为2.26%~27.16%和2.30%~32.69%。节水灌溉减小了稻田生态系统白天CO_(2)净吸收通量,增大了稻田生态系统夜间CO_(2)净排放通量,白天吸收和夜晚排放的变化幅度为2.68%~59.79%和1.26%~40.95%。研究结果可为实现稻田水资源高效利用及充分发挥稻田生态系统的碳汇功能提供理论依据。

To reveal the effects of different water and carbon management on CO_(2) exchange between paddy ecosystem and atmosphere,based on field experiments,the diurnal variation characteristics of net CO_(2) flux in paddy field ecosystem under different water and carbon management modes were analyzed.The results showed that the change trend of net CO_(2) flux in paddy field ecosystem at tillering stage,jointing and booting stage and milky stage was U-shaped,which showed that it was generally absorbed during the day and discharged at night,and the net absorption stage and net emission stage in each growth period were consistent in time.With the advance of growth period,the net CO_(2) absorption duration and amount in daytime of paddy field ecosystem presented the trend of increasing at first and then decreasing.In addition to the treatment of high amount of biochar at tillering stage,which reduced the net CO_(2) absorption flux in the paddy field ecosystem during the day,the application of biochar increased the net CO_(2) absorption flux during the day and the net CO_(2) emission flux in the night of the water-saving irrigation paddy field ecosystem.Compared with the treatment without biochar,the net CO_(2) flux of paddy field ecosystem during the day and at night were increased by 2.26%-27.16%and 2.30%-32.69%under the two biochar conditions.Water-saving irrigation reduced the net absorption flux of CO_(2) in paddy field ecosystem during the day,but increased the net emission flux of CO_(2) in paddy field ecosystem at night.The variation ranges of daytime absorption and night emission were 2.68%-59.79%and 1.26%-40.95%.The research results could provide a theoretical basis for realizing the efficient utilization of paddy field water resources and giving full play to the carbon sink function of paddy field ecosystem.