Novel avenues of mitigation of rice paddy methane: a review

The upsurge in global population in the past few decades has played a pivotal role in increasing anthropogenic activities like paddy cultivation, livestock rearing, etc., an eminent source of rise in methane emission in all the ecosystems, grossly afflicting the global biomass. The term "global warming" and its adverse impact on sustainability have slowly become ubiquitous, permeating conversations, scientific discussions, and political debates across globe. Rice paddy ecosystem is a prime source of emitting methane, a greenhouse gas, present abundantly in troposphere and has a strong link to global warming, especially in Southeast Asia. Despite its intricacy, the mechanisms and factors driving methane dynamics in rice fields are well-established, such as soil pH, redox potential, temperature, flooded condition, and microbe community in rhizosphere. Methane production results from the anaerobic breakdown of source organic carbon in flooded paddy fields, facilitated by methanogens like Methanobacterium, Methanogenium, etc. This accounts for 90% of the emission being released in the atmosphere through aerenchyma of rice plants, diffusion through liquid phase (waterlogging), or ebullition (bubble formation), accelerating greenhouse gas (GHG) emission. Presently, green synthesis of nanotechnology offers a sustainable solution to reduce greenhouse gas emissions, though there are delimiting challenges that are yet to be resolved, amalgamating with newer eco-friendly mitigation approaches like water management, application of biochar, selection of rice cultivars, and modification of tillage.