This week, the Ohio Newsroom is joining NPR to tell local stories about climate solutions, as the federal government walks back environmental regulations.
In Cincinnati, local parks have been using an ingredient called biochar to help trees grow. They鈥檝e been purchasing it from out of state, but soon, the city will be making its own.
On Arbor Day in 2025, Cincinnati Mayor Aftab Pureval announced the city鈥檚 first use of biochar for tree planting to an enthusiastic crowd: elementary school students.
鈥淢ake some noise if you love trees,鈥� Pureval exclaimed to loud cheers. 鈥淗ere鈥檚 the most exciting thing, guys 鈥� you are part of history. Today, we are using a magical ingredient for the first time in Cincinnati鈥檚 history. It鈥檚 called biochar.鈥�
Biochar is more science than magic, but it鈥檚 pretty powerful. The charcoal-like material can enrich soil and keep climate-warming carbon out of the atmosphere.
What is biochar?
Cincinnati Parks Director Jason Barron says the parks produce a lot of wood waste, like dead trees and trimmed branches.
鈥淎nd that wood waste was just decomposing and releasing that carbon back in the air,鈥� Barron said. 鈥淎nd this allows us to take what we already have and turn it into something that's beneficial.鈥�
To make biochar, wood is burned at a high temperature with little oxygen, which traps the carbon so it can鈥檛 get out. When it鈥檚 mixed with compost or manure, it becomes an excellent fertilizer, helping plants grow faster and taking even more carbon out of the atmosphere.
Cincinnati is working with a private company, Carbon Harvest LLC, to build a warehouse with a machine that can make biochar on a large scale.
The new facility will produce at least 300 tons of biochar a year. About two-thirds will be sold, making the project financially self-sustaining in the long run.
Barron says what鈥檚 left will be mixed with manure from a farm and equestrian center at a county park, then used to plant trees in Cincinnati. The goal is to grow trees faster and increase the urban tree canopy.
鈥淚've been thinking about it as a quilt,鈥� said Carbon Harvest owner Sam Dunlap. 鈥淲e're trying to restore soil health with one patch of land at a time 鈥� and we can make ourselves, our city, much more climate resilient and healthy by building this quilt of healthy soils.鈥�
Neighborhoods with fewer trees experience . And in Cincinnati, lower-income neighborhoods tend to have the fewest trees.
Crystal Courtney is trying to change that. She manages the city鈥檚 urban forestry with Cincinnati Parks, and just last month helped plant 27 trees at an elementary school in Over-the-Rhine.
鈥淭he biochar and the compost will provide more nutrients than what you see in our very clay-ey soil here,鈥� Courtney said. 鈥淪o it will hold more nutrients and moisture close to the root system over time.鈥�
Newly-planted trees often struggle in urban environments. has found a biochar and compost mix helps urban trees grow faster and live longer.
鈥楨verything is on the table鈥�
Biochar鈥檚 worldwide potential is much broader. The process of making biochar can also produce
And when it comes to resource-intensive agriculture, biochar can increase crop yields while decreasing dependence on climate-polluting fertilizers.
So, could biochar save the world?
Not quite, says Rattan Lal, distinguished university professor of soil science at the Ohio State University.
鈥淐limate change is such a humongous problem that humanity and planet Earth has never seen before,鈥� Lal said, adding the first step is to stop burning fossil fuels.
鈥淔or this humongous problem, there is no one solution. Everything is on the table,鈥� he said.
That includes biochar 鈥� and Jason Barron says Cincinnati wants to lead the way. He鈥檚 hoping other cities follow in their footsteps and start making biochar, too.
鈥淯ltimately, that will lead to not just healthier, faster growing trees in Cincinnati, but faster growing trees throughout the region,鈥� Barron said. 鈥淎nd then growing that industry and growing that technology across the country.鈥�