Microbial biomass carbon and methane oxidation influenced by rice cultivars and elevated CO₂ in a Japanese paddy soil

Abstract

Microbial biomass carbon (C) and methane oxidation activity influenced by rice cultivars and elevated atmospheric CO 2 were investigated in a microcosm experiment in two controlled-environment chambers with CO 2 concentrations at 370 μl l −1 (ambient) and 570 μl l −1 (elevated). Four rice cultivars were grown in sandy paddy soil in this experiment; these were IR65598, IR72, Dular and Koshihikari. Soil microbial biomass C under elevated CO 2 was significantly larger (by 18.9-25.2%) than that under ambient CO 2 , and varied with the cultivars in the sequence IR72 > Dular > IR65598 > Koshihikari. Methane oxidation activity in the soil also differed among the cultivars, in the sequence IR72 > Dular > Koshihikari > IR65598, but was larger under elevated CO 2 than under ambient CO 2 only with IR72. Methane oxidation activity was positively correlated with microbial biomass C among four cultivars under two CO 2 conditions. This study indicated that microbial biomass C in paddy soil varied among the rice varieties examined, but was increased significantly by elevated CO 2 and correlated with methane oxidation, which may in turn influence methane emission to the atmosphere.

Soil Organic Matters

“…The reason is not clear but perhaps could be associated with the very long-term cultivation of soils at this site, even those soils that had reverted to woodland over 100 years ago. Inubushi et al (2011) used a microcosm approach to investigate CH 4 oxidation in a paddy soil from Japan under the influence of oxygen reaching the anaerobic soil via the rice plant. They found differences in oxidation rates between rice cultivars, with rate being correlated with the size of the soil microbial biomass.…”

Uncertainties in the national inventory of methane emissions from rice cultivation: field measurements and modeling approaches

“…Certain factors, such as rice biomass (Bachelet and Neue, 1993), organic matter input (Kern et al, 1995), water management (Khosa et al, 2011;Mishra et al, 1997), paddy soil properties (Yao et al, 1999;Gaunt et al, 1997), climate (Sass et al, 1991), and rice varieties (Su et al, 2015;Ding et al, 1999), have been recognized as having significant impacts on methane emissions. Other factors, such as atmospheric CO 2 and ozone contents (Dijkstra et al, 2012;Bhatia et al, 2011;Inubushi et al, 2011), N fertilizer application (Banger et al, 2012;Xie et al, 2010a), and active soil organic C (Zhan et al, 2011), and even the field management of rotation crops (Weller et al, 2016), are also receiving increasing attention. Because so many factors affect the production, oxidation, and emission of methane from rice cultivation, the observed methane fluxes varied extensively both spatially and temporally.…”

“…However, the range of national and/or global source estimates remains large (Cao et al, 1996;Sass et al, 1999;Chen et al, 2013). The major factors that are known to regulate rice paddy methane emissions include agricultural management practices (Khosa et al, 2011;Sanchis et al, 2012;Sass et al, 1992;Bodelier and Laanbroek, 2006) and environmental conditions, such as climate and soil properties (Conrad et al, 2007;Inubushi et al, 2011;Sass et al, 1991). Currently, techniques for calculating methane emissions differ substantially and usually consist of scenario simulations (Ito and Inatomi, 2012;Van Bodegom et al, 2002a, b;Verburg et al, 2006), without integrated consideration of methodological fallacy and data insufficiency.…”

“…Until the significant reduction in methane emissions caused by mid-season drainage was confirmed (Sass and Fisher, 1997;Yagi et al, 1997;Li et al, 2002;Yan et al, 2005), all previous regional and national estimates (obtained using extrapolation or regression equations) were derived from continuously flooded rice fields. More factors, such as the (Watanabe et al, 1995;Butterbach-Bahl et al, 1997;Ding et al, 1999;Inubushi et al, 2011) soil properties (Sass et al, 1994;Yao et al, 1999), atmospheric CO 2 (Dijkstra et al, 2012;Xie et al, 2010b), and ozone (Bhatia et al, 2011) concentrations involved in rice cultivation, have also been incorporated into models designed to estimate methane emissions from rice paddies. Complex interactions among these factors have spurred model development (Cao et al, 1995;Li, 2000;Matthews et al, 2001;Huang et al, 1998Huang et al, , 2004Van Bodegom et al, 2001).…”

Development of temporary subtropical wetlands induces higher gas production

“…The main local controls of CO 2 productions from wetlands include the quality of soil organic substrates (Updegraff et al, 1995). Given the diverse variables that control the emission of methane and other gases from wetland environments (Yang and Chang, 1998; van der Nat and Middelburg, 2000; Conrad, 2002; Hirota et al, 2004; Whalen, 2005; Liikanen et al, 2006; Cheng et al, 2007; Welsch and Yavitt, 2007; Kao-Kniffin et al, 2010; Khosa et al, 2010; Inubushi et al, 2011), evaluating these processes and the effects of participating microorganisms is a complex task.…”