Journal of Taiwan Agricultural Research

Author:Ming-Hwi Yao* and Shou-Hung Chen

Abstract:

    The uptake of carbon dioxide in rice paddies may play an important role in balancing the budget of greenhouse gases, but there is considerable uncertainty in the magnitude of the net fluxes from the related ecosystems. The Bowen ratio/energy balance (BREB) technique was used to measure CO₂ fluxes over a paddies field site at Wufeng, Taichung. As a result, the average net daily CO₂ uptake in first crop was 22 g m^-2 day^-1, while it was 17.9 g m^-2 day^-1 in second crop. Differences in the CO₂ budget between the two growing seasons are due mainly to the different leaf area index (LAI). The peak LAI coincided with peak net CO₂ fluxes during growing periods. Soil CO₂ flux was found responsive to changes of soil water content. However, CO₂ exchange rate can be neglected in the submerged soil. In addition, when comparing the carbon gain measured in the chamber system and open-path system, the closed environment was found underestimated, specially under high light condition.

Key words:Climate change, Greenhouse gas, Rice, CO₂ flux, Bowen ratio/energy balance (BREB) system

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