Effect of oxidizing and reducing agents in soil on methane production in Southeast Asian paddies

Abstract

Methane is one of the greenhouse gases emitted from paddy soil ecosystems and may induce global warming and climate change; therefore, mitigation options are urgently required to establish mitigation technology to reduce methane emission without affecting rice production. Methane is produced by a balance between oxidizing agents (such as iron) and reducing agents (easily decomposable soil organic matter), according to the so-called Takai theory. To evaluate options for mitigating methane production potential and to examine the applicability of the Takai theory in Southeast Asian paddy soils, 23 soil samples were collected from Thailand, Indonesia, Philippines, and Vietnam. These soil samples were anaerobically incubated to measure their methane production potential and examined to see whether their chemical properties, such as the ferrous, total iron, and organic matter contents, were correlated. We found a significant negative correlation between the methane production potential and the total iron content, and a positive correlation between the methane production potential and the hexose content, as an index for a soil's easily decomposable organic matter content. The methane-C/CO 2 -C production ratio was also positively correlated with the mineralizable nitrogen/ferrous contents ratio, which indicated that the Takai theory, established for Japanese paddy soils, is also useful in Southeast Asian paddy soils and that the soil's iron content is important to estimate the methane production potential. ARTICLE HISTORY

Sustainable soil management in East, South and Southeast Asia

“…In these studies, it was also found that CH 4 production decreased when Fe and fertilizers containing S were added (Inubushi, Umebayashi, and Wada 1990a;Inubushi et al 1997b;Furukawa, Tsuji, and Inubushi 2001). The balance and relationship between oxidizing agents, especially soil Fe, and reducing agents, namely soil organic matter, on methane production was investigated in Southeast Asian paddy, and results showed a similar relationship between oxidizing and reducing agents as has been observed in Japanese paddy soils (Inubushi et al 2018).…”

Water Quality Assessment in Relation to the Surrounding Soil Management of Two Reservoirs in Pindorama/Sp - A Preliminary Study

“…Moreover, as turbidity levels in both reservoirs were low, it is unlikely that sediments affected the measurements made by the probe. Further investigation is necessary to identify what factors are contributing to making the reservoirs reducing environments as high concentrations of electron donors such as easily decomposable soil organic matter can also be the cause of the detected low ORP levels (INUBUSHI, 2018).…”

Fe(III) stabilizing soil organic matter and reducing methane emissions in paddy fields under varying flooding conditions

“…Low O 2 availability could slow microbial respiration and activity (Hall and Silver, 2015;McGroddy and Silver, 2000). When O 2 is depleted in soil, Fe undergoes the oxidation and reduction of biogeochemical reactions (Inubushi et al, 2018). Therefore, O 2 accessibility has significant impacts on both redox and SOM mineralization.…”