Researchers discover that a small organism has the power to reduce a persistent greenhouse gas in agricultural fields

In the world of greenhouse gas emissions, carbon dioxide gets most of the blame. But small organisms that flourish in the world’s agricultural fields emit a much more potent gas, nitrous oxide, and scientists have long sought a way to solve this problem.

Now, some researchers think they’ve found a bacteria that might help. Writing in this week’s Nature, they say that extensive laboratory and field tests showed that the naturally derived bacteria reduced nitrous oxide without disturbing other microbes in the soil. It also survived well in the soil and would be relatively cheap to produce.

“I think the path we’ve blazed here opens up a number of new possibilities in bioengineering crop soil,” said Lars Bakken, professor at the Norwegian University of Life Sciences and one of the study’s authors. .

A pound of nitrous oxide—better known as laughing gas, the substance that relaxes people in the dentist’s chair—can heat the atmosphere 265 times more than a pound of carbon dioxide and can persist in the atmosphere for more than a century. Farmers’ heavy use of nitrogen fertilizers increases the amount produced in the soil and, in 2022, was responsible for 6% of all greenhouse gas emissions from human activities in the U.S., according to the Environmental Protection Agency.

Reducing fertilizer use may help, but crop yields would ultimately decline.

This is a big problem in agriculture, “so the fact that they developed a unique strategy to drastically reduce it was really interesting,” said Lori Hoagland, professor of soil microbial ecology at Purdue University, who was not involved in the study.

Bakken and his colleagues used organic waste to grow their bacteria, reasoning that many farmers already apply processed manure-based fertilizers so they could be easily integrated into their routines. Building on previous work, they looked for a microorganism that would last long enough to cause a true reduction in nitrous oxide emissions without remaining in the soil so long as to disrupt other tiny life forms that are often vital to crop health.

In field tests, they used roving robots to measure nitrous oxide emissions day and night, comparing soil conditions with and without the bacteria. They found that the bacteria reduced nitrous oxide emissions from an initial fertilizer application by 94% and, a few weeks later, reduced emissions from a subsequent fertilizer application by about half. After about three months, there was no difference in the composition of the microbial life forms, suggesting that their bacteria would not disturb the soil.

The bacteria in which they settled – Cloacibacterium sp. CB-01 — is found naturally in anaerobic digesters, machines that are already being used to transform organic waste, such as cow manure, into biofuels. The fact that the bacteria is not genetically modified could make it easier to accept and adopt, said Paul Carini, a soil microbiologist at the University of Arizona who was also not involved in the research.

Bakken said the bacteria could be included in certain fertilizers on farms within three to four years, if the economics make sense.

Carini thinks so.

“Anytime you use a waste product from one industry to benefit another industry, that’s quite cost-effective,” he said.

However, Bakken pointed out that farmers are not paid to reduce nitrous oxide emissions and believes there should be more incentives to do so. “The authorities’ task is to install political instruments that make it profitable in one way or another,” he said.

Hoagland, the Purdue professor, said more research under field conditions would likely be needed before the bacteria could be deployed worldwide, as there are many different types of agricultural soils.

“If they can get this to work on soils and other things, it would have a tremendous impact, for sure,” she said.

It’s a challenge that has long vexed academics as well as major agricultural companies trying to develop organisms that can be added to soil to achieve beneficial effects, Carini said. He said that although many investigations in this regard have been irregular, this one has had clearer results.

Like Hoagland, he said more work is needed to prove the bacteria’s effectiveness. But he called the work a model for selecting beneficial organisms that can be added to soil.

“I think this is the next frontier in agricultural soil research,” he said.

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Follow Melina Walling on X: @MelinaWalling.

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