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.”
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