Comparison of Closed Chamber and Eddy Covariance Methods to Improve the Understanding of Methane Fluxes from Rice Paddy Fields in Japan

Abstract

Greenhouse gas flux monitoring in ecosystems is mostly conducted by closed chamber and eddy covariance techniques. To determine the relevance of the two methods in rice paddy fields at different growing stages, closed chamber (CC) and eddy covariance (EC) methods were used to measure the methane (CH4) fluxes in a flooded rice paddy field. Intensive monitoring using the CC method was conducted at 30, 60 and 90 days after transplanting (DAT) and after harvest (AHV). An EC tower was installed at the centre of the experimental site to provide continuous measurements during the rice cropping season. The CC method resulted in CH4 flux averages that were 58%, 81%, 94% and 57% higher than those measured by the EC method at 30, 60 and 90 DAT and after harvest (AHV), respectively. A footprint analysis showed that the area covered by the EC method in this study included non-homogeneous land use types. The different strengths and weaknesses of the CC and EC methods can complement each other, and the use of both methods together leads to a better understanding of CH4 emissions from paddy fields.

Nitrous Oxide Emissions from Paddies: Understanding the Role of Rice Plants

“…Current methodologies involved in field-based measurements of N 2 O emissions from paddies include closed static chamber-based methods [18,59] and the micrometerological approach (the eddy covariance method) [10,60,61]. These methods include both soil and rice plants in the same system [10,18,[59][60][61], making it difficult to evaluate the role of rice plants. However, for other plants with bigger stems (like trees), recent studies have developed separate chambers that help to capture the fluxes of N 2 O by avoiding soil N 2 O emissions [62].…”

“…The chamber used for trees cannot be used for crop species, like rice. The studies taken in field conditions [18,[59][60][61] have not developed such chambers that could separately quantify the N 2 O emitted from the rice plant and the rice soil. In this regard, static chambers that could be used for crops like the rice plant should be developed and the N 2 O fluxes from the rice plant and the rice soil (microbial) should be measured separately.…”

Greenhouse Gas Emission from Rice field in Indonesia: Challenge for future research and development

“…Ultimately, using a combination of both methods enables better understanding of CH 4 emissions from paddy elds. Measurements using the CC method resulted in higher CH 4 ux averages than using EC (Chaichana et al, 2018). Li et al (2020) used modi ed Moderate Resolution Imaging Spectrodiameter (MODIS) data to capture spatial patterns in rice paddies over several years accurately.…”

Evaluation of CH4MOD<sub>wetland</sub> and Terrestrial Ecosystem Model (TEM) used to estimate global CH<sub>4</sub> emissions from natural wetlands

“…The observations in this study used both the chamber method and the eddy covariance method (Aubinet et al, 2012), which are widely used for CH 4 observations (Table 1). There are differences in measuring CH 4 fluxes between the two methods (Chaichana et al, 2018). The eddy covariance method may underestimate the fluxes (Twine et al, 2000;Sachs et al, 2010), while the chamber method may overestimate the fluxes (Werle and Kormann, 2001).…”

“…Some wetland types have higher emissions, while some emit less CH 4 ; this difference is because the processes of controls on CH 4 cycling differ among wetland types (Bridgham et al, 2013). For example, sedge-dominated marshes or fens often emit higher CH 4 fluxes, because sedges can increase methanogenic substrates as part of their plant productivity and promote CH 4 transportation through their soft aerenchyma and lacunae tissues (McEwing et al, 2015;Jitka et al, 2017;Bhullar et al, 2013;Joabsson and Christensen, 2001;Kwon et al, 2017;King et al, 2002;Chanton, 2005). Bog soils with anaerobic incubations emit little CH 4 due to the particularly high CO 2 : CH 4 ratios of the end products of anaerobic carbon (Bridgham et al, 1998;Galand et al, 2010;Keller and Bridgham, 2007).…”