By: Ryan Summerlin
A three-year project to rejuvenate long-barren soils in Coal Basin and other tracts damaged by mining has shown promise by tapping a technique thousands of years old.
Coal Basin has been one petri dish in a mine reclamation experiment aiming to promote rich soil composition and regrowth of vegetation with native grasses.
On the 17,000-acre watershed in the White River National Forest west of Redstone, the U.S. Forest Service started the project in 2012 with a 40-acre section that had a road system and mine tailings called the Sutey Pile.
The road was heavily compacted Mancos Shale that had become like concrete after decades of heavy trucks running on it, said Brian McMullen, a soil scientist who headed the project.
At the Sutey Pile, where the mining operation processed its coal, waste rock and coal were left over. It was more rock than soil, he said. “It’s a nasty medium to try to grow anything on.”
In this area, the average topsoil depth was only about 6 inches.
When measuring soil conditions, soil is considered healthy when it’s made up of more than 5 percent organic matter, said McMullen.
But at the project site in Coal Basin, organic matter was measured at about 3.6 percent.
The area’s soil was also low in what McMullen called “litter”: dead plants scattered on the topsoil that are good for the soil’s resistance to erosion, its ability to hold moisture and promote organic matter.
To create better soil conditions in the area, the project added a mixture of compost material from the South Canyon Landfill and biochar.
Biochar can be made using wood chips, peanut shells or any number of combustible waste materials. It undergoes a similar process to making charcoal, but the difference, said McMullen, is that you use high temperatures and low oxygen.
The resulting material ends up high in carbon and low in oxygen, so it’s more stable and doesn’t break down so easily with rain and other interactions with the atmosphere, he said.
The biochar has a lot of charged surfaces, making it good at strongly binding water and nutrients, acting like a sponge, said McMullen.
Biochar comes from an ancient technique that was rediscovered in the Amazon rainforest.
The Amazonians, instead of practicing slash-and-burn agriculture, were digging pits and covering their burned material with soil, which reduces the oxygen, said McMullen. The result was a highly coveted, fertile soil, he said.
It’s now being retweaked with different devices to create those same conditions, said McMullen.
But there are many ways to get this material worked into the soil. The project at Coal Basin used intense cattle traffic, hundreds of heads of cattle, concentrated in a small space over short segments of time.
“This technique allows the hoof action of cattle to incorporate organic material and seed into the soil. Additionally, the livestock naturally fertilize with urine and manure.
“Having a rough surface is an important concept in revegetation; you don’t want it to look like a golf course. You want microsites for vegetation to take hold.”
Comparing the soils that had this mixture with an adjacent tract as a control subject, the soil with compost and biochar saw much higher moisture concentration, higher organic matter, higher nutrients and a higher number of soil microbes.
The soil microbes are also an important and often-overlooked piece of soil health because they help cycle nutrients and eventually become nutrients themselves when they die, said McMullen.
With the naked eye, you can see the distinct difference in vegetation cover between the areas treated with the compost and biochar mixture and the ones that weren’t, he said.
This technique is getting domestic and international attention, such as from companies in the skiing and oil and gas industries implementing their own projects.
The Sutey Pile is the only site so far that’s utilized cattle, but this project included dozens of project sites that span every district of the White River National Forest.
But biochar, because it’s an engineered product, is much more expensive on a cubic yard basis than topsoil. From the company that this project used, the material starts at $195 per yard. The recipe this project used called for about one part biochar to nine parts compost, said McMullen.
There’s a carbon cycle side to this story; using biochar is a way to put carbon into the ground rather than emitting it into the atmosphere, he said. “This is anther reason to look at this material more, not just for soil erosion and vegetation.
“My hunch is that over the long run, the biochar will pay off because it’s more stable and will stick around. It will take a long view to justify the cost. But if you do, our results show it will be worth the additional cost.”
Partnering with the forest were the Crystal Valley Environmental Protection Association and the Coal Basin Cattlemen’s Association. The project also received money from local governments, including Garfield and Pitkin counties, Aspen, Basalt and Carbondale.