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After the Fire - Wood Waste Put to Work

Posted by Carla Bamesberger, Rocky Mountain Research Station, USDA Forest Service in Forestry Research and Science
Jul 29, 2021
Wood waste that can be converted into biochar
Non-merchantable, or low value, wood waste such as this can be converted into biochar. USDA Forest Service photo by Deborah Page-Dumroese.

Biochar, or wood waste, is a porous carbon substance that results from burning wood in the absence of oxygen. It is typically created when burning chunks of wood are covered by ash, soil or a lid, which insulates the coals and starves them of oxygen. This fire remnant provides a valuable addition to soil for agriculture and gardening purposes as well as contributing to overall forest health.

When added to soil, biochar increases soil carbon and can restore the soil’s pH balance. Soil with a high carbon content is teeming with life and rich in nutrients, requires less fertilizer and produces healthier food. Carbon-rich soil also absorbs and retains water more efficiently, which helps farmers reduce the effects of floods and drought.

“One thing to keep in mind is that biochar does not add nutrients to the soil, but it can help retain them,” said Forest Service research soil scientist Deborah Page-Dumroese. “Biochar is 80 percent carbon, and that’s the big-ticket item. Adding biochar to soil increases soil’s water-holding capacity, which leads to less runoff and leaching, better infiltration, higher water quality and better downstream water flow because more moisture is retained in the soil.”

Biochar also helps restore soil that has been damaged by fire or human activity. Biochar can be easily made in well-constructed slash piles and be used on-site to restore soil organic matter. In places where this method is used, biochar has extended vegetation growth by nearly a month, resulting in reduced fire risk.

Biochar pile
Biochar is a porous carbon substance that helps increase the water-holding capacity of soil. USDA Forest Service photo by Deborah Page-Dumroese.

Despite its usefulness, biochar is difficult to produce in large quantities for agricultural, forestry or commercial use. With healthy forests in mind, the USDA Forest Service Rocky Mountain Research Station and Air Burners, Inc. teamed up to optimize biochar production for the marketplace. The company has partnered with the Forest Service through a cooperative agreement to help find a solution to this market problem. The company’s commercial fireboxes, used for processing wood and vegetative waste, are being modified to produce high-quality biochar.

“We’re using non-merchantable forest residues to create biochar,” said Page-Dumroese. “We’ve been testing a forest-to-farm concept in Oregon, where low-value woody biomass, a byproduct of harvest operations, is uniform and abundant. It makes sense that we match the pace and scale of harvest operations to that of biochar production.” Using the Air Burner (and other) production technologies, the Forest Service can help deliver biochar to unirrigated agricultural production markets to extend the economic, social and ecological benefits of our forest restoration efforts.

Applying biochar can even reduce invasive species growth and help native species expand their range. Since many invasive species prefer a nitrogen-rich environment, biochar can reduce invasive species by tying up nitrogen in many soil types. Biochar has also been successfully used in western forests during removal of old roads to restore them to a natural condition and to restore soils after thinning, among other applications.

Biochar pellets
Biochar pellets are easy to transport and spread. USDA Forest Service photo by Deborah Page-Dumroese.
Category/Topic: Forestry Research and Science

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Mike Wagner
Jul 26, 2019

I am a Master Gardener and Forestry Professor Emeritus. I have added biochar to my garden for several years and it appears to be having a positive impact. Every time I read an article on biochar I wonder how it is different than charcoal? Burning wood in absence of oxygen has been going on for centuries. What is the key difference between biochar and charcoal?

Lorna Smith
Jul 29, 2019

We have 120 acres mostly timber in a variety of ages. We have 14 areas in CREP and have done some EQUP. We do Permaculture
Islands and do year round gardening in our hoop house and 3’ x 3’ solar cones. As a fire prevention we have been cutting limbs up around the many wood lots so have a lot of branches to chip, pile or make into bio char. At 67 years old my husband and I can not do as much as we used to but still we do a lot. We are interested in the up scale process if it is possible to set up our own burner. We have done it on a small scale. Thanks for your consideration and suggestions. We appreciate our timbered land and hope it can be of aid with the trend of climate change.

Lorna and Carl Twin Brooks Farm Chehalis est 1953

Aug 09, 2019

I am concerned about the forest dep chipping up blow down limbs and spreading this fire fuel all along the highway from Oak Ridge to La Pine and other places too.
All it will take is for one fool to throw out a cigarette and it will go up like a match.
Is this the kind of management Oregon's forests have?

Tisa Tulgetske
Sep 05, 2019

Good article about biochar. Been using it for years. Every time I plant anything from flowers to trees I add a mixture of biochar and microbials into the topsoil. The results are truly amazing. I add microbials to each of my trees, plants, shrubs and flowers twice each year with outstanding results like more flowers blooming, increased number of fruit produced, and stimulated growth in my trees and shrubs. I've introduced the combination of biochar and microbials to family and friends all over the USA with shocking results, to include flowers not normally grown in a region actually thriving. If farmers would cultivate their soils with biochar and microbials, I'm 100% sure they'd see an increase in food production. Great article, hopefully the Forest Service will include microbials to the mix with the biochar.

Stephen Feher
Oct 14, 2019

Interested in further information specifically related to biochar production in Air Burners. Please provide references to actual Air Burner equipment type (Model No?) and description of process. I am involved in R&D to utilize large amounts of waste biomass left over from tree removal after the Camp Fire. We will have access to two Air Curtain Burners on loan from CalFire this winter, but we are not familiar with their use for biochar production. Any advice would be appreciated.

Stephen I. Feher