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The Promise of Biochar for Forests, Grasslands, and Farms

Ancient Amazon tribe leaves behind enduring model of soil conservation.

Diane Banegas
Research & Development
August 24, 2017 at 12:45pm

Forest Service soil scientist Jim Archuleta first learned of biochar’s promise a few years ago when one of his colleagues mentioned it while they carpooled to and from work.

“He was a wildlife biologist who wanted to feed elk,” Archuleta said. “He was trying to improve their forage in the middle of the summer on the Umpqua National Forest in Southwestern Oregon, a nutrient-poor environment.”

Jim Archuleta, Forest Service scientist

Forest Service soil scientist Jim Archuleta. Forest Service photo by Joanie Bosworth (retired).

His colleague had researched how prehistoric Indians living in the Amazon created biochar by burning vegetation and putting the resulting “black carbon” material in the soil. The practice made it possible for them to spend their entire lives living and growing crops in one location. The biochar replenished the soil’s nutrients by increasing its nutrient exchange and water holding capacity, which indirectly helped prevent erosion. The resulting Terra Preta (literally “black earth”) soil of the Amazon is a remarkable manmade legacy with higher nitrogen, phosphorus, potassium and calcium concentrations than other soils in the region. This incredible soil has retained its fertility for thousands of years. Archuleta’s biologist friend thought improving forest soil like the Amazon Indians did might in turn result in better grazing for the elk. With the use of this ancient method, they were able to keep grass green into August in a place called Fish Creek Desert.

“He wanted my opinion on the matter, because I’m a soil scientist,” Archuleta said. “The more I read about how the Amazonian Indians built up soil nutrients and structure with biochar, the more I began to see its potential for healthy forests and farms, as well as healthy elk.” Archuleta, who now works on the Umatilla National Forest located in the Blue Mountains of southeast Washington and northeast Oregon, also knew there was a readily available source of organic material for conversion into biochar.

The Forest Service conducts thinning projects on national forests to reduce crowded stands of trees and remove excess fuels that make forest fires so dangerous. These projects leave behind piles of slash—cut limbs, tree tops, and brush—that in themselves have no commercial value. An existing technology called the Air Curtain Burner converts slash piles into ash to reduce fuel loads and fire risk. It can make biochar, but the process needs to be stopped and charcoal removed once the unit is cooled; in batches. The Forest Service envisioned a faster and more efficient process that continuously pumped out pellets at the end of the operation while workers fed slash into the adapted equipment. This process should work twice as fast as the existing technology and produce a valuable end product.

Archuleta and his colleague Debbie Page-Dumroese at the agency’s Rocky Mountain Research Station began working together in 2009. “Part of the focus shifted to biochar production when we realized its broad application and value, he said.” They modified the design of existing air curtain burner technology to produce biochar in large quantities. The charcoal by itself will increase a soil’s ability to hold water, but it’s not considered biochar until it’s loaded with nutrients and influences biologic activity.

Archuleta and Page-Dumroese have filed for patent on the technologies with assistance from the Forest Service’s Technology Transfer Coordinator Tom Moreland. Biochar holds promise for farm land in western states, where dry land farming practices are common. It also holds special promise in arid eastern Oregon. 

Coarse and pelleted biochar

Biochar in coarse and pelleted form. Forest Service photo by Jim Archuleta.

“Biochar addresses low soil organic matter, adds nutrients, and significantly improves a field’s water carrying capacity,” Archuleta said.  He is collaborating with Stephen Machado, lead scientist at Oregon State University’s Columbia Basin Agricultural Research Center to see if biochar can help dry land wheat farmers. 

 In spite of its promise, biochar is not a panacea. “We need to be careful where we put it,” Archuleta noted. For example, because of its water carrying capacity, on the wrong slope, unintended consequences may occur. But used prudently, Archuleta thinks the “forests to farm” uses of biochar are exciting.

As a soil scientist who has spent much of his career working through the “NEPA” process mandated by the National Environmental Protection Act, he also believes biochar may address a frequent public comment when the Forest Service plans to thin excess fuel from a forest. “Many times people have commented to me that Forest Service harvesting activities do not truly mimic the restoration effects of natural wildfire," as we state in project proposals,” Archuleta said. “Thinning with an application of biochar does.”

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