V2I8P45

Role of Microbes in Climate Change: Methanogens and Methanotrophs in Carbon Cycling: A Case Study of Agbede Rice Fields, Edo State, Nigeria

Arashiya Jerry^1*, Ugah Chukwuemeka S², Anyira-Fasanmi Mary Ifeoma²

Abstract

Climate change is a pressing global challenge, with greenhouse gases such as methane (CH₄) playing a pivotal role in atmospheric warming. Wetland ecosystems, including rice paddies, are significant sources of methane due to the metabolic activities of methanogenic archaea, while methanotrophic bacteria act as natural sinks by oxidizing methane before its release into the atmosphere. This study investigates the role of methanogens and methanotrophs in carbon cycling within rice cultivation areas of Agbede, Edo State, Nigeria, an agrarian region characterized by intensive rice farming and seasonal flooding. Soil samples collected across five sites were analyzed for physicochemical parameters, microbial abundance, and methane flux. Results showed higher methanogen counts during the wet season (4.8 × 10⁶ cells/g soil) compared to the dry season (2.1 × 10⁶ cells/g soil), while methanotroph populations peaked in moderately aerated zones (3.5 × 10⁶ cells/g soil). Methane flux measurements indicated emission rates ranging from 12.4 to 25.7 mg CH₄/m²/day, with the highest values recorded in waterlogged paddies. A strong positive correlation (R² = 0.81) was observed between methanogen abundance and CH₄ emission rates, whereas methanotroph activity negatively correlated with flux values (R² = –0.67). These findings highlight the dual role of microbial communities in regulating greenhouse gas dynamics in rice ecosystems. The study underscores the importance of sustainable rice field management strategies, such as intermittent drainage and organic soil amendments, to mitigate methane emissions while maintaining productivity. Insights from Agbede rice fields contribute to the broader understanding of microbially mediated carbon cycling in tropical agricultural wetlands.

Keywords:

Methanogens, Methanotrophs, Carbon Cycling, Rice Fields, Methane Emissions, Edo State