Observation of Methane Flux in Rice Paddies Using a Portable Gas Analyzer and an Automatic Opening/Closing Chamber

Choi, S.W.; Kang, M.S.; Kim, J.H.; Sohn, S.W.; Cho, S.S.; Park, J.H.

Observation of Methane Flux in Rice Paddies Using a Portable Gas Analyzer and an Automatic Opening/Closing Chamber

2023

Methane (CH4) emissions from rice paddies are mainly observed using the closed chamber method or the eddy covariance method. In this study, a new observation technique combining a portable gas analyzer (Model LI-7810, LI-COR, Inc., USA) and an automatic opening/ closing chamber (Model Smart Chamber, LI-COR, Inc., USA) was introduced based on the strengths and weaknesses of the existing measurement methods. A cylindrical collar was manufactured according to the maximum growth height of rice and used as an auxiliary measurement tool. All types of measured data can be monitored in real time, and CH4 flux is also calculated simultaneously during the measurement. After the measurement is completed, all the related data can be checked using the software called ‘SoilFluxPro’. The biggest advantage of the new observation technique is that time-series changes in greenhouse gas concentrations can be immediately confirmed in the field. It can also be applied to small areas with various treatment conditions, and it is simpler to use and requires less effort for installation and maintenance than the eddy covariance system. However, there are also disadvantages in that the observation system is still expensive, requires specialized knowledge to operate, and requires a lot of manpower to install multiple collars in various observation areas and travel around them to take measurements. It is expected that the new observation technique can make a significant contribution to understanding the CH4 emission pathways from rice paddies and quantifying the emissions from those pathways.

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