Carbon Credits for Methane Emission Reductions in Paddy Fields

Rice farmers in India can now earn additional income by reducing methane emissions through climate‑smart, water‑saving practices and by monetising these reductions as carbon credits.

The Issues with Traditional Rice Farming

• In conventional rice cultivation, farmers often keep fields continuously flooded (around 4–5 cm water depth) for roughly the first two months after transplanting.
• The main purpose is weed control, as the standing water creates an oxygen-free (anaerobic) environment that prevents weed seeds from germinating.
• This same waterlogged condition is ideal for methanogenic microbes, which decompose organic matter in the soil and produce methane.
• Methane is a potent greenhouse gas, with 28 times the global warming potential of carbon dioxide over 100 years.

Alternate Wetting and Drying (AWD)

• Alternate Wetting and Drying (AWD) is a water management technique for growing irrigated rice with less water than the conventional method.
• By allowing fields to dry periodically before re-flooding, it reduces water use and methane emissions.
• This periodic drying interrupts the anaerobic conditions, significantly reducing methane production.
• International Research: The International Rice Research Institute (IRRI) has been a key promoter of AWD as a smart water-saving technology, especially in Asia.

Benefits of Alternate Wetting and Drying (AWD)

• Water Savings: AWD fields used 3.14 million litres/acre, compared to 4.96 million litres/acre in continuously flooded (CF) fields.
• Methane Reduction: AWD fields emitted 3.5 tonnes of CO2 equivalent/hectare, versus 6 tonnes/hectare from CF fields.
• No Yield Loss: Critically, the average grain yield remained the same (approx. 2.5 tonnes/acre) under both methods.

The Carbon Credit Opportunity for Farmers

• The reduction in methane emissions can be converted into sellable carbon credits once verified under a recognised standard. 
• These credits are bought by companies (like data centres or airlines) to offset their own emissions.
• Carbon credits for methane reduction trade at about $15-25 per tonne of CO2 equivalent.
  • With AWD reducing emissions by about 2.5 tonnes of CO2 equivalent per hectare per crop, a farmer can potentially earn at least $37.5 per hectare per crop cycle.
  • This translates to roughly ₹1,363 per acre – a significant additional income.

AWD Projects in Practice

• Mitti Labs (India):  Working with tens of thousands of farmers across multiple Indian states.
  • Approach: Uses digital technology to track water levels and verify practice adoption.
  • Documented Result: Achieved 37% water savings with maintained yields in a study in Telangana.
• Green Carbon (Vietnam): Project in six northern provinces, with plans for major expansion.
  • Approach: Partners with national agricultural institutes for technical support and data collection.
  • Documented Result: Reported ~55% methane reduction and a 5.5% yield increase in Nghe An province.

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