Rice farming releases methane emissions primarily due to the anaerobic (oxygen-free) conditions created in flooded paddy fields. Here's how the process works:

 Rice farming releases methane emissions primarily due to the anaerobic (oxygen-free) conditions created in flooded paddy fields. Here's how the process works:

1. Flooded Fields Create Anaerobic Conditions

-Rice is typically grown in flooded paddies, which cut off oxygen from the soil.

-This lack of oxygen creates the ideal environment for anaerobic microbes to thrive.

2. Organic Matter Feeds Microbes

-Plant residues, such as rice straw, root exudates, and soil organic carbon, begin to decompose in the waterlogged soil.

-As this organic matter breaks down, it becomes food for methanogenic archaea — microorganisms that produce methane.

3. Methanogenesis Begins

-Methanogens convert the decomposed organic matter into methane (CH₄) via biochemical processes, such as:

-Acetoclastic methanogenesis (acetate → CH₄ + CO₂)

-Hydrogenotrophic methanogenesis (CO₂ + H₂ → CH₄)

4. Methane Rises and Escapes

-Methane produced in the soil escapes into the atmosphere through three primary pathways:

-Diffusion and bubbling through the water column.

-Cracks in the soil, especially if it dries and re-floods.

-Through the rice plant itself, via hollow stem channels called aerenchyma, which act as natural pipes for methane to travel from roots to the air.

5. Global Impact

-Methane is a potent greenhouse gas, with 25 times the warming potential of CO₂ over a 100-year period.

-Rice farming contributes significantly to global methane emissions, accounting for about 10% of agricultural CH₄ emissions worldwide.

Mitigation Options

-Alternate wetting and drying (AWD): periodically draining paddies to allow oxygen into the soil.

-Straw management: removing or composting plant residues instead of incorporating them into the soil.

-Improved rice varieties and nutrient management can also reduce emissions.

~ NGA Geography