BACKGROUND: To quantify carbon exchange at agricultural ecosystems in South Korea, net ecosystem exchange (NEE) at three croplands including a rice paddy, a bean field and an apple orchard are measured on the basis of the eddy covariance technique.
METHODS AND RESULTS: NEE of CO2 during the growing season (June to September) averaged over the recent two years (2018-2019) is the highest at rice (-4.49 g C m-2 day-1), followed by the bean (-3.12 g C m-2 day-1) and apple (-0.93 g C m-2 day-1). The diurnal variation of NEE is the highest at the rice, while the seasonal variation of it is the highest at the bean than others. In terms of yearly variation, the rice paddy and the bean field absorbed more CO2 in 2019 compared to 2018, while the apple orchard absorbed less.
CONCLUSION: Our results confirmed that these croplands consistently acted as net sinks for CO2 during the growing season because an amount of CO2 uptake from photosynthesis is larger than one of its emissions from respiration. The quantification of net CO2 exchange at agricultural ecosystems may help to better understand the local carbon cycle over various time scales.