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Biochar — an ancient farming method — is finding new life improving soil and burying carbon

As the country tries to meet its climate goals, tackling emissions from farming will be key. One climate-smart agriculture strategy sequesters carbon while recycling agricultural waste and improving soil.

Nick Cuchetti is mixing up something special in a bucket on his family farm in Luebbering, Missouri.

The dusty substance looks a lot like charcoal, but scientists who study it bristle at the comparison. This is biochar — a soil amendment and a hot topic in sustainable agriculture.

As Cuchetti pours the biochar onto his farmer’s market vegetable beds, you can hear what makes this substance special. It tinkles, almost like broken glass; its hollow and porous nature makes biochar uniquely suited for improving soil.

But for Cuchetti, a lot of biochar’s appeal has to do with something else — fighting climate change. Burying biochar on a farm also sequesters carbon.

“You put it in soil, it's just there,” Cuchetti said. “You can just forget about it. It's gone.”

Agriculture is the fifth-largest source of greenhouse gas emissions in the U.S., so finding ways to cut down carbon while farming is key to meeting national climate targets.

But there’s a lot more to the climate-friendly practice. Biochar proponents say it creates a sustainable cycle of benefits on farms, also helping recycle waste, lessen the need for fertilizers, improve soil and even potentially help crops survive longer in droughts.

An ancient practice

Biochar is made by recycling agricultural waste. Crops pull in carbon dioxide, then instead of letting waste like corn stalks decay, releasing that carbon, the biomass is cooked at a high temperature with extremely low oxygen. The process traps the carbon, creating biochar that can be buried in the ground.

Isabel Lima first became interested in biochar more than 20 years ago, before scientists were even calling it that, because she wanted to address the “incredible amounts of waste that agriculture produces.” Lima is a research chemist with the U.S. Department of Agriculture and sits on the board of the U.S. Biochar Initiative, a nonprofit that advocates for biochar.

“Agriculture likes to talk about the nice fruits of agriculture, which is what we see at our dining table, but we don't ever see the waste product,” Lima said. “So biochar is beautiful in that it actually uses those resources to make something that is of significant value.”

Indigenous people in the Americas have been using something like biochar for centuries, Lima said. They would burn agricultural waste and put it back in the soil in places like Brazil.

“We go there and look very deep in the soil in the Amazon, for example, and we determined that those soils that we would otherwise expect to be very infertile are actually very fertile because of those practices hundreds and hundreds of years ago,” Lima said.

There’s still more scientists hope to learn about biochar. Lima said some of the biggest questions surround how the effects and properties of biochar change based on the different processes and agricultural waste used to make it.

But decades of extensive research have revealed a lot about biochar’s unique ability to capture carbon and how it affects the soil. Lima explains it improves soil structure and health, which helps crops grow better, faster and larger. Research has also shown it creates a really friendly environment for microbes. And because the biochar is super porous, it might also help soil hold onto water and fertilizer, Lima said.

That’s something farmer Scott Booher has seen first hand. He owns Four Winds Farm with his wife in eastern Iowa, where they grow organic hemp, flowers and herbs. When Booher and his wife first started farming their land in 2020, they had a soil test done.

“It was lacking in lots of different areas,” Booher said. “So we spent a good bit of money on phosphorus, potassium, nitrogen.”

They also applied biochar. Since then Booher hasn’t had to add fertilizer again. Less fertilizer is easier on the environment and cheaper, but Booher said the biochar cost benefit takes a while to show up.

“If you're in it for the long haul, I think it's a great investment,” Booher said. “But it is quite an expense upfront.”

Catching on with farmers

Cost is one of the biggest hurdles to widespread use of biochar, said Myles Gray, program director at the United States Biochar Initiative.

“It's a relatively small industry,” Gray said. “It's growing very quickly and a lot of that growth is related to the carbon benefits of biochar.”

Thanks to the Inflation Reduction Act, Gray said there are new federal funds to incentivize climate-friendly farming practices, including biochar. That funding is coming in part through the USDA’s Natural Resources Conservation Service, which provides funding to farmers using practices that are good for the environment, including biochar.

But while it is an ancient practice, modern biochar is still relatively unknown among farmers.

Back in Missouri, Cuchetti is something of an ambassador for biochar. One of his first jobs out of college included selling the soil amendment to farmers, and now he promotes it as secretary of the Missouri Organic Association and as a conservation agronomist for Carbon Smart Ag.

The beds he is preparing will grow vegetables for a St. Louis farmer’s market, where he and his wife will also be selling grass-fed beef. He’s looking forward to talking about his growing practices with customers, too.

“I love educating people on regenerative agriculture and what they're actually buying,” Cuchetti said. “Because you can't go to Walmart and ask how this is being produced. Go to the farmer’s market and you can do that.”

He’s especially excited that biochar offers a long-term climate solution on his own farm. Cuchetti points out that other regenerative practices — like no-till and cover crop farming — can be reversed quickly when someone new takes over the land. That means the carbon that had been stored is suddenly released.

“Well, you put biochar out there, I don't care who owns it,” Cuchetti said. “It's not gonna be economically viable to go get it back out. You know, it's fixed.”

While experts don’t know exactly how long biochar remains in the soil, they believe the carbon will stay locked in for hundreds of years — perhaps long enough to be rediscovered and studied by humans again.

This story was produced in partnership with Harvest Public Media, a collaboration of public media newsrooms in the Midwest. It reports on food systems, agriculture and rural issues.

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