Demonstration project aims to show ag value of forest biochar 

Laura Lundquist

(Missoula Current) After helping with several forest thinning projects in the Missoula area, former Missoula District Forest Service Ranger Jennifer Hensick knows the limitations of such efforts.

For example, she remembers walking through the Marshall Woods area as that project was underway about three years ago. Thinning had opened up forest, but the associated slash piles were everywhere. At certain locations, she could spread her arms wide and touch neighboring slash piles with her fingertips.

Those piles were of no use to anyone, so they would have to be burned.

“I just thought there’s got to be a better way,” Hensick said.

There may be a better way if a forestry demonstration project in the Blackfoot River drainage can show there’s an economic benefit to turning slash into biochar.

On Tuesday morning, about two dozen people representing the U.S. Forest Service, the Bureau of Land Management, the Blackfoot Challenge and The Nature Conservancy traveled up Gold Creek Road to an area where thinning is being carried out on private and BLM land.

They passed large piles of young green trees that had been cut during the past month, leaving open stands of golden larch and Douglas fir.

Farther up the hill, a large log grabber trundled along the top of a wood pile, plucking bundles of skinny trees and depositing them in what looked like a long yellow dumpster. But this was no dumpster. It was the “Carbonator,” a Tigercat biochar incinerator, which was taking all the slash being dumped in the top and then pumping it out of the bottom as 2-inch chunks of biochar. 

Greenside Construction owner Tom Elder said the wood inside the incinerator was burned at 2,500 to 3,000 degrees Fahrenheit using a fire that was fueled only by wood and oxygen. A lot of the smoke was also recycled through the incinerator to burn the particles out so the smoke that is released is less polluting.

Once the wood burns down to a small enough size, the chunks fall through the grate of 2-inch holes and are mixed with water so they’re cool enough to maneuver into piles of biochar.

One of the great things about the resulting pile of biochar is that it’s only 10% the size of the tree pile it came from, Elder said. So at least Hensick’s slash piles are diminished.
But what is biochar? And what good is it?

“Biochar is essentially charcoal. It’s any organic matter that you burn with limited oxygen through a process called pyrolysis,” said Barry Dutton, soils consultant to the Blackfoot Challenge. “The great thing about it is you can think of it like a bowling ball that has all these convoluted surfaces. All those pockets can retain water and provide habitat for microorganisms that convert minerals and organic matter into substances that plants can use. Biochar can increase the moisture and nutrient holding capacity of soils.”

That may sound beneficial, but does it work? 

On a small scale, it appears to. People spread biochar from small “ring of fire” burners in campgrounds and yards to improve vegetation. But the concept of modern biochar is fairly new, so there’s not a lot of research about using the large amounts that would come from forestry projects.

As part of the demonstration project, some landowners with the Blackfoot Challenge, including Denny Iverson and Brad Hall, have agreed to apply biochar to their land to see how much biochar can be applied and how well it works. 

Dutton is so excited about biochar’s potential to improve the soil that he came out of retirement to work with Blackfoot Challenge landowners.

“No one has looked at doing it on the scale we are,” Dutton said. “We’re going to take this biochar and apply it to a variety of ag fields; in plots in plowed situations and unplowed situations, in irrigated and unirrigated, in grazed and ungrazed. This is not a research plot. We’re doing a field trial. We’re going to establish plots, take this stuff and spread it. And if we come back in the future and it looks great, we’ll put out signs to tell people the benefits of biochar.”

Actually, the entire demonstration project is a field trial that will also determine the best methods and conditions for using mobile incinerators, said Beth Dodson, University of Montana professor of forest operations. Dodson’s graduate student Klem Krasaitis is closely monitoring the daily operations on different lands and with different conditions to produce a report for future project managers.

“We’re trying to look at what is the cost and what are the production rates,” Dodson said. “That’s part of a larger project I’m involved with the Forest Service that looks at where does this make sense? We have a number of options for how we might produce biochar. And really big picture, how can we be as efficient as possible?” 

The benefit of a mobile Tigercat incinerator is it can create biochar on site. Otherwise, project managers would have to haul the trees to a stationary incinerator, if one is nearby, and that costs more money. But with the process being relatively new, there are only about a half-dozen mobile Tigercat incinerators in the U.S. 

The Nature Conservancy had to hire Greenside Construction and its carbonator out of Portland, Ore. They arrived last Tuesday but will be working at the site for 10 days. Currently, they’re trying to incinerate all the recently cut wood on the BLM site, and then they’ll move to Forest Service land where the slash has been drying since spring. The process goes faster with dryer wood.

But the difficulty in scheduling the incinerator meant Dutton and his landowners didn’t have time to figure out how to spread the biochar on their plots in time for this fall. The biochar piles will have to wait until spring.

That will give the Blackfoot Challenge time to work out a few of the issues that remain. For instance, Dutton isn’t quite sure how much biochar they can put on the land or they’ll spread it. Perhaps they’ll use a manure spreader or a gravel truck, but they may have to screen out the smaller sticks that fall through the grate. Iverson also noticed that the biochar piles contained a fair amount of pine needles, which can be poisonous to cattle. 

If they get those issues figured out and biochar is shown to improve ag lands, that would show biochar has value. Dutton said it’s likely that some of that value could come from people wanting to buy carbon offsets because biochar can endure in the soil for centuries. 

But it’s still not clear how project managers could get more incinerators working on forest projects. BLM Fire management specialist Michael Albritton said it was unlikely that the BLM would buy an incinerator, which cost $650,000 in 2019. 

“We’re generating the slash, and we’d love to be able to give it to someone who wants it. It would be great if private industry saw some value in that slash pile, enough to want to buy a machine,” Albritton said. “One group was saying they were thinking of building a stationary facility in Anaconda. That wouldn’t help us, but it might help the Butte BLM office. But if a contractor in Montana bought one, I think they would get work.”

The project is funded by grants from the Montana Department of Natural Resources and Conservation Forest Action Plan Implementation Fund and the USFS Wildfire Adapted Missoula Joint Chiefs Restoration Program.

Contact reporter Laura Lundquist at lundquist@missoulacurrent.com.