Rice is the pillar of Vietnamese agriculture but also a significant source of methane emissions. Alternate wetting and drying (AWD) is seen as a key solution that cuts emissions, saves water and opens the door to carbon markets.

Why rice cultivation emits methane

In continuously flooded fields, anaerobic conditions favor methane-producing microbes that decompose organic matter and release methane, a greenhouse gas far more heat-trapping than CO2. Reducing continuous flooding directly limits methane generation, which is the core principle of AWD.

What is alternate wetting and drying?

AWD is a water-management technique in which fields are allowed to dry naturally during certain periods instead of remaining flooded, then re-irrigated as needed.

  • Let the field dry to an appropriate level before re-irrigating
  • Use a water-level tube to decide irrigation timing
  • Keep water during sensitive stages such as flowering
Illustration of a rice field using alternate wetting and drying AWD
AWD manages water in wet-dry cycles to reduce methane emissions in rice fields.

Benefits of AWD

  • Reduced methane emissions, potentially substantial
  • Water savings of around 20–30%
  • Lower pumping and input costs
  • Stronger roots and less lodging

Carbon-credit opportunities for rice farmers

When emission reductions are measured and verified under standard procedures, they can be converted into carbon credits and traded. This offers additional income for farmers, tied to large-scale programs for high-quality, low-emission rice. Participation requires transparent measurement, reporting and verification, plus production organized at sufficient scale.

AWD shows that cutting emissions and farmers' economic gains are not opposites but can go hand in hand when properly organized and measured.

Research and transfer directions

Measuring and verifying emissions

Turning emission cuts into carbon credits requires a reliable measurement, reporting and verification system. Methane can be estimated via direct field measurement or models based on water and season data.

  • Keep detailed records of irrigation and drainage each season
  • Measure emissions at representative points
  • Apply emission factors suited to Vietnam

An integrated cultivation protocol

AWD works better within an integrated protocol combining suitable varieties, sensible sowing density, balanced fertilization and integrated pest management. Organizing large-field production and linking farmers is key to applying AWD consistently and reaching the scale needed to join carbon markets feasibly.

Wide adoption of AWD requires suitable irrigation infrastructure, practical technical guidance and reliable emission measurement. ASTRI Institute treats low-emission rice cultivation and agricultural carbon-credit mechanisms as an important research, application and technology-transfer direction, aiming to help farmers access sustainable techniques and seize opportunities in the low-carbon economy.