Investigating the relationship between temperature and soil CO2 emission according to paddy water condition

Abs tr ac t. The soil CO2 emissions from rice paddy fields have a significant influence on net CO2 fluxes throughout the year. Unlike other agroecosystems, rice paddy fields are flooded for most of the growing season. Over the course of this study, soil CO2 emissions in rice paddy fields were observed under fallow, flooded, and drainage conditions using a closed-system portable chamber. It was found that the dried and bare soil in fallow paddy systems emit a significant amount of CO2. On the other hand, the CO2 released from the soil during flooding periods was suppressed by the water layer. In drainage conditions, the exponential curve of the relationship between soil CO2 emissions and soil temperature was particularly evident. These results suggest that soil CO2 emissions during fallow and drainage periods can exceed the level of CO2 emissions that is suppressed under flooded conditions. However, immediately after draining or the occurrence of a rainfall event, the suppression of soil CO2 emission by residual paddy water will provide valuable insights in the interpretation of agricultural carbon cycle models.