In soils, biochar can increase aeration, reduce emissions of greenhouse gases, reduce nutrient leaching and acidity and can add more water content in coarse soils. (Submitted photo)
Agraria offers climate hope through biochar workshop
- Published: December 5, 2024
Most of us know charcoal as the small, black briquets we use to grill or smoke food for backyard barbecues, or to rid our compost buckets of their characteristic odor. But an upcoming workshop at Agraria hopes to educate folks about a kind of charcoal, known as biochar, that has the potential to reinvigorate soil and help mitigate climate change.
Agraria will host a biochar workshop Friday and Saturday, Dec. 6 and 7, at Agraria Farm. The hands-on workshop will be led by instructors Mark Cohen, Gary Gilmore and Dale Hendricks, all of whom spoke with the News last week.
Cohen, who is a current member of Agraria’s board of directors, has a varied background in wildlife biology and anthropology, and helped co-found Far Valley Farm in Southeastern Ohio, where he said he’s lived “off the grid” for more than 40 years. Gilmore and Hendricks are both based in Pennsylvania; Gilmore is retired from former careers as, first, a blacksmith, and then 25 years with the Bureau of Forestry. Hendricks’ background is in horticulture; he ran a large wholesale nursery specializing in native plants for many years.
The three said they first learned about biochar through their common interest in permaculture, which led them all to discover terra preta — a fertile soil found in the Amazon River basin in South America. Part of what makes terra preta remarkable, they said, is that it was created by Indigenous people who added biochar to the soil over the course of hundreds of years.
“It just hit me, like a light bulb went off, realizing that fire produced all this charcoal, which got incorporated in the soil over millennia,” Gilmore said.
“It just completely blew my mind that the basis of it was charcoal,” Cohen agreed. “I was completely hooked for life at that point.”
Since then, the three instructors have presented workshops on biochar together, both in Ohio and other U.S. states. Their workshops focus on the many applications of biochar — including, they said, how it can help slow climate change by sequestering carbon and keeping it in a stable form.
It works, more or less, like this: Carbon dioxide that might otherwise act as a greenhouse gas, trapping heat in the earth’s atmosphere, is absorbed by a plant — in this case, let’s say a tree. Sunlight, chlorophyll, carbon dioxide and water react to create glucose in the tree, releasing oxygen, and the leftover carbon from photosynthesis grows into the tree’s leaves, branches and trunk.
Trees can keep carbon out of the atmosphere for as long as they live — but once a tree is dead, both its natural decay over time or burning its wood in an oxygenated environment will create carbon dioxide. Creating biochar, however, keeps oxygen — and thus the potential bonding of carbon and oxygen into carbon dioxide — out of the equation.
“Wood is heated in the absence, or near absence, of oxygen, and most of the hydrogen and oxygen are driven off, leaving the carbon behind — and that’s charcoal,” Gilmore said. “It’s basically stable carbon.”
Hendricks added: “A log, if you leave it where it is in the woods, will gradually rot and turn into soil — and within 10 to 50 years, that carbon will be back in the atmosphere. … But charcoal is long, long, long, long-lasting — many, many generations in the soil.”
In fact, because biochar is so resistant to decay, it can sequester carbon in soil for hundreds, perhaps thousands, of years.
While it’s there, buried in the soil, what else can biochar do for the earth? Unlike short-term carbon, produced as plant matter breaks down in the soil, biochar’s stable carbon doesn’t act as a food source for soil microbes. But it does, Hendricks and Cohen said, have a tremendous capacity to hold onto water and nutrients, preventing them from being leached out of soil.
“It’s the best delivery system you can think of for any kind of nutrients,” Hendricks said. “But it isn’t a nutrient in and of itself — it’s a long-term structural investment in soil health and nutrient capacity.”
Cohen added that biochar can be likened to a battery, “charging” as it absorbs particles, nutrients and minerals from the soil.
“As time goes by, it is holding enough life in it that it’s creating active nutrients, just like your gut microbiome is creating active nutrients,” he said. “It isn’t a fertilizer per se, but if you get it loaded with biology as well as minerals, it’s going to be equivalent and better than a fertilizer.”
When it comes to urban soils, which are often hard and laden with clay, the three said, biochar can be particularly helpful, allowing the hardened soils to absorb more water, where it might otherwise run off.
“The worse soil is, the better effects you’re going to see by the addition of biochar,” Hendricks said, with Gilmore adding: “Urban soils are hammered, but charcoal can hold water in its pores, and it can tie up elements that you may not want in your plants, like lead or chromium.”
The uses of biochar aren’t confined to carbon sequestration and soil amendment; its ability to absorb makes it good for filtering wastewater, and it’s often used to reduce odors.
Nodding to his blacksmithing days, Gilmore said he used biochar in the past to fuel a forge, and that it can also be used to fuel machinery — which Gilmore said he does regularly. He noted that, due to fuel rationing, vehicles around the world used wood or char gas during World War II.
“In a nutshell, you’re adding oxygen and producing carbon monoxide, which is a combustible gas. It doesn’t have the power of natural gas or gasoline, but it is enough to run an internal combustion engine,” he said. “I have a generator, tractor and wood splitter I can run on charcoal.”
He added, with a laugh: “I even have a truck that can run on it — but it messes with the computer, and it derates the engine by about 30%.”
Cohen said the option to use biochar as fuel has added value for farmers in that it could lessen their reliance on fossil fuels and lend a certain amount of autonomy to their practices.
“For somebody who’s lived off the grid for 45 years, I look at not only autonomy, but resilient backup systems — so that’s a whole conversation in itself,” he said. “And we will cover all these different topics in the course.”
Importantly, the workshop will also instruct participants in how to create biochar at home — which the instructors said is a process accessible to anyone who’s able to burn a campfire in their backyard. The part of the burning process that excludes oxygen to stabilize burning wood into carbon, called pyrolysis, can be completed in sealed metal drum barrels.
“It’s all in how you control the fire,” Gilmore said. “The wood burns in several phases; that glowing charcoal, that’s what you want to pull out and then exclude the oxygen from it. And that’s what you use in your soil — simple as that.”
The three said that, apart from educating workshop participants on the varied uses of biochar and instructing them on how to create it themselves, they hope the workshop will embolden folks to think creatively and hopefully about how to combat climate change.
Cohen said the current conversation around climate is “deeply broken,” leaving people without adequate knowledge around mitigation possibilities.
“When you combine a knowledge of the carbon cycle and the water cycle, you have immediate traction in the positive direction that is absolutely missing from the entire climate conversation,” he said. “We’re hearing that carbon dioxide is this boogeyman that is automatically making everything hopeless — it’s not. So this is a hopeful set of ideas.”
The biochar workshop led by Cohen, Gilmore and Hendricks will be held Friday, Dec. 6, 5–8 p.m.; and Saturday, Dec. 7, 9 a.m.–5 p.m. Cost is $125 per participant. For more information, and to register, go to http://www.agrariacenter.org/events-2-1/biochar-workshop.
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