Microbial Methane Production-Oxidation Profile in the Soil of Mangrove and Paddy Fields of West Bengal, India

Abstract

A comparative vertical profile was performed regarding methane production, methanogenic population, methane oxidation and methanotrophic population in the soil of Sundarban mangrove forest, a paddy field at Namkhana (near to Sundarban mangrove) and a paddy field at Burdwan (non-mangrove region) during pre-monsoon, monsoon and post-monsoon along with selected physicochemical parameters. Maximum methane production rate (8.70 mmol m−2 day−1) was found from the soil collected from 60 cm depth from the paddy field of Burdwan which was 1.42 and 1.79 times higher than that of Sundarban mangrove forest and paddy field of Namkhana, respectively. However maximum methane oxidation rate (3.30 mmol m−2 day−1) was found from the surface soil of Sundarban mangrove forest during monsoon season which was 1.25 and 2.70 times higher than that of paddy field of Namkhana and Burdwan, respectively. An increasing vertical trend was found for the ratio of methanogenic population to methanotrophic population and Methane production rate to methane oxidation rate for the studied stations suggested dominance of methanogens in the deeper soil. Both those two ratios were maximum for paddy field of Burdwan suggested maximum methane flux from this station than other two stations due to presence of a smaller number of methanotrophic bacteria. All three stations showed significant correlation between methane production with methanogenic population and methane oxidation with methanotrophic population throughout the year suggested major microbial contribution in the net flux of methane from the soil.