Planting certain types of rice could help curb methane emissions

Choosing the right kind of rice doesn’t just affect taste or yield – it can actually change how much methane escapes into the atmosphere.

A global team studying 180 rice varieties found that genetics, more than fertilizer, can determine how much methane a field produces.

Led by Conor Walthall of Cranfield University, the research pulled together data from 42 trials across several countries. The takeaway? Some rice varieties naturally emit far less methane than others, even under the same fertilizer conditions.

Breeding smarter, cleaner rice

By contrast, nitrous oxide – a long-lived, heat-trapping gas – rose mainly with nitrogen application. Yield gains leveled near 180 to 200 kilograms of nitrogen per hectare (about 161 to 178 pounds per acre).

“Nitrogen application rate was the primary driver of N2O emissions and crop yield, while genotypic differences significantly influenced CH4 emissions,” said Walthall.

The global dataset gives scientists a clearer map of which rice varieties are naturally lower emitters.

Turning that knowledge into regional results requires testing these varieties under local soils, water schedules, and weather patterns. What works in a flooded delta may not perform the same way in a dry upland.

New breeding tools such as genomic selection, a method that predicts crop performance based on DNA data, can help breeders find promising low-methane traits faster.

Combining field trials with digital soil and water sensors will also reveal how specific genetic traits interact with farm environments, closing the gap between global analysis and local yield gains.

Root traits that release gas

Rice roots contain aerenchyma – air-filled tissue that moves gases between soil and air. A classic study showed these structures help methane move from paddies into the atmosphere.

Varieties also differ in how much oxygen their roots release and what compounds their roots leak. Those traits change microbial methane production belowground.

Over 20 years, methane warms about 81 times as much as carbon dioxide, and nitrous oxide about 273 times, according to the IPCC table. Cutting methane from rice therefore matters even when total tons look small.

From lab to rice fields

Applying this knowledge means looking for rice lines that release less methane yet still yield well in local conditions.

Breeding programs can track traits like smaller aerenchyma and efficient nitrogen uptake to find combinations that cut emissions naturally.

Public seed banks and agricultural institutes could integrate these traits into regional breeding targets. Over time, selecting for low-methane performance could make climate-smart rice a standard option rather than a specialty variety.

When nitrogen tips the scale

Multiple field datasets show nitrous oxide climbs sharply as nitrogen rates exceed crop needs. A global meta-analysis found the rise is faster than linear for many systems.

Yield-scaled nitrous oxide fell as nitrogen moved from low toward moderate rates. Efficiency improved because each ton of grain carried more output.

Breeding for higher nitrogen-use efficiency, how well a plant turns fertilizer into grain, can reduce the nitrogen needed for the same yield. That eases pressure on nitrous oxide without a yield penalty.

Cutting emissions on the rice farm

Screen rice lines for low methane under common flooded and alternate wetting regimes. Measure yield-scaled emissions, emissions divided by harvested yield, to avoid per acre illusions.

Pair that genetic testing with careful nitrogen timing and rate. Right-sized applications cut nitrous oxide without sacrificing productivity.

Consider traits linked to low methane, like smaller aerenchyma or different root exudates. Direct measurements remain essential before release.

Linking rice and climate policy

Reducing methane through crop genetics could help countries meet Paris Agreement targets without forcing farmers to overhaul irrigation or fertilizer practices.

Because many national greenhouse gas inventories include methane from rice as part of agricultural emissions, genetic improvements could directly lower reported totals.

Climate finance programs are beginning to reward emission cuts linked to better crop management or selective breeding. These initiatives connect specific plant traits to verified reductions in greenhouse gases.

The results could pave the way for inclusion in carbon credit markets and sustainability certification programs. Together, these efforts offer farmers a tangible financial incentive to grow low-methane crop varieties.

Still, most of the available data come from rice grown in Asia, where many studies relied on static chambers. That means the results are strongest for flooded systems and may underestimate short-lived emission bursts.

Multi-site trials across different crops, soil types, and climates remain rare, and expanding that research will be essential to turn laboratory insights into real-world results.

Global impact beyond rice paddies

Lower methane varieties could make a measurable dent in global warming potential since rice farming accounts for about 10 percent of agricultural greenhouse gases worldwide.

Widespread adoption of low-emission lines could equal the climate benefit of removing millions of cars if implemented across major rice-producing countries.

The same approach could extend to other crops. Identifying traits that cut nitrous oxide or carbon dioxide emissions in wheat, maize, or canola could multiply the climate gains from breeding alone, aligning agriculture with long-term net-zero goals.

The study is published in the journal Frontiers in Agronomy.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–