Alternate Wet Drying (AWD): The Rice Farming Technique Helping Reduce Methane Emissions

Rice is one of the world's most important food crops, feeding more than half of the global population. However, many people are surprised to learn that rice farming is also a significant source of greenhouse gas emissions.

According to the United Nations Food and Agriculture Organization (FAO), rice cultivation contributes around 10% of global agricultural methane emissions. Because methane is more than 25 times more powerful than carbon dioxide at trapping heat over a 100-year period, reducing emissions from rice farming has become an important part of climate action.

One promising solution is a farming method known as Alternate Wet Drying (AWD).

Why Do Rice Fields Produce Methane?

Traditional rice farming keeps fields continuously flooded throughout much of the growing season.

When soil remains underwater for long periods, oxygen levels become extremely low. Under these anaerobic conditions, naturally occurring microorganisms break down organic matter and produce methane gas.

The methane then escapes into the atmosphere through the water surface and even through the rice plants themselves.

As a result, continuously flooded rice paddies become one of the largest agricultural sources of methane worldwide.

What Is Alternate Wet Drying (AWD)?

Alternate Wet Drying is a water management technique that allows rice fields to dry periodically instead of remaining permanently flooded.

Rather than maintaining standing water at all times, farmers allow the water level to naturally fall after irrigation. Once the water drops to a predetermined depth below the soil surface, the field is irrigated again.

This creates a cycle of:

• Flooding

• Drying

• Re-flooding

without harming rice yields.

The technique was developed and promoted by the International Rice Research Institute (IRRI) and is now being adopted in countries across Asia.

How Does AWD Reduce Methane Emissions?

The science behind AWD is relatively simple.

Methane-producing microbes thrive in oxygen-poor environments. When the soil is allowed to dry periodically, oxygen enters the soil and disrupts the conditions needed for methane production.

Studies have shown that AWD can reduce methane emissions by approximately 30–70%, depending on soil conditions, climate, and management practices.

This makes AWD one of the most practical and cost-effective methods available for reducing agricultural greenhouse gas emissions.

Water Savings: An Additional Benefit

Beyond reducing emissions, AWD also helps farmers conserve water.

Research has found that AWD can reduce irrigation water use by around 15–30% compared with conventional flooding methods.

This is particularly important in regions facing:

• Water shortages

• Drought conditions

• Increasing competition for freshwater resources

As climate change places greater pressure on global water supplies, improving water efficiency has become just as important as reducing carbon emissions.

Does AWD Affect Rice Yields?

One of the most common concerns among farmers is whether reducing water use will reduce crop production.

Fortunately, most studies show that properly managed AWD can maintain rice yields while using less water.

In some cases, farmers have even reported improved root development and stronger plant growth due to better soil aeration.

However, successful implementation requires careful monitoring of water levels to avoid excessive drying that could stress the crop.

Challenges to Adoption

Despite its benefits, AWD is not suitable for every situation.

Farmers may face several barriers, including:

Infrastructure Limitations

Some irrigation systems are designed for continuous flooding and may require upgrades to support AWD practices.

Knowledge and Training

Farmers need guidance on monitoring water levels and determining the correct timing for irrigation.

Local Conditions

Soil type, rainfall patterns, and regional climate can all affect AWD performance.

For this reason, local field testing and agricultural extension support are often essential for successful adoption.

Real-World Success Stories

Countries including India, Vietnam, Bangladesh, Thailand, and the Philippines have already begun implementing AWD on a large scale.

Projects supported by governments, research institutions, and international climate organisations have demonstrated that AWD can reduce emissions while helping farmers lower water costs and improve resource efficiency.

In India alone, thousands of farmers have adopted AWD practices as part of climate-smart agriculture programmes designed to improve both environmental and economic outcomes.

Why AWD Matters for the Future

Feeding a growing global population while reducing greenhouse gas emissions is one of the biggest challenges facing agriculture today.

Unlike many climate solutions that require expensive technology or major infrastructure investments, Alternate Wet Drying offers a practical approach that farmers can implement using existing rice production systems.

By reducing methane emissions, conserving water, and maintaining crop yields, AWD represents an important step toward more sustainable food production.

As governments and agricultural organisations continue searching for climate-smart farming solutions, Alternate Wet Drying is likely to become an increasingly important tool in building a more resilient and environmentally responsible agricultural sector.

Final Thoughts

Rice farming will remain essential to global food security for decades to come. The challenge is finding ways to produce enough food while minimising environmental impacts.

Alternate Wet Drying demonstrates that small changes in farming practices can deliver significant environmental benefits. By reducing methane emissions and improving water efficiency, AWD offers a practical example of how sustainable agriculture can help address climate change without compromising food production.