Application of the Chamber Method for Carbon Flux Measurement in Tea Plantations: Insights from Irrigation Renovation Projects

In recent years, Taiwan has extended irrigation services to regions previously devoid of water resources. These irrigation improvement projects incorporate sustainable engineering practices and are aligned with the objectives of Nature-based Solutions (NbS), enhancing ecosystem protection, mitigating climate impacts, and reducing economic losses associated with extreme weather events such as droughts and floods. Beyond these benefits, this study aims to investigate the additional value of these projects as they provide opportunities for carbon reduction initiatives. Should local measurements meet expectations, further development of methodologies, such as the Measurement, Reporting, and Verification (MRV) process, will be pursued. This research examines the effects of irrigation infrastructure upgrades on carbon dynamics within tea plantations, focusing on the reduction of carbon emissions and the enhancement of soil organic carbon (SOC). Three sites were selected for this purpose: two tea gardens employing different irrigation techniques and a derelict area formerly used for tea cultivation, with each site covering more than 0.5 hectares. The study assesses two crucial parameters: SOC, which indicates the carbon sequestered in the soil, serving as a carbon sink, and the carbon emissions from tea trees. The chamber method, a recognized approach for collecting greenhouse gas (GHG) emissions, was utilized to capture emissions from tea trees using transparent chambers. Field experiments are conducted monthly, with gas sampling occurring every two hours throughout the daylight hours. The collected gas samples are analyzed via Gas Chromatography-Mass Spectrometry (GC-MS) to ascertain carbon concentrations, which are subsequently used to calculate daily carbon fluxes. Preliminary results from several months of gas sampling indicate significantly lower carbon emissions in the well-irrigated tea garden, where the renovation was implemented, compared to the garden without irrigation. Furthermore, SOC levels in the irrigated garden are anticipated to show marked improvement over the previous year.