Biochar: An Ancient Solution to a Modern Global Crisis
Ken Carloni, Ph.D.
biochar /ˈbīōˌCHär/ noun: charcoal produced from plant matter and stored in the soil as a means of removing carbon dioxide from the atmosphere. (Online Dictionary)
When the Portuguese first arrived in Amazonia, they discovered small islands of dark, highly productive soils associated with indigenous villages. Unlike other notoriously poor soils in the region that became depleted after just a few years of cultivation, these soils have remained productive after centuries of continuous farming. The Portuguese named these soils “terra preta de índio” (black earth of the Indian), and they are now known simply as terra preta soils.
A few decades ago, anthropologists discovered that these soils contained significant amounts of broken pottery, animal bones, charcoal, and other materials common to “kitchen middens”. Some of these “anthropogenic” terra pretas were created nearly 2500 years ago! Further investigations showed that the key ingredient that made these soils so productive (and dark) was the biochar. The upheaval of indigenous lifeways brought on by the arrival of European cultures and diseases caused this traditional ecological knowledge to become lost as settled agrarian peoples became more nomadic to avoid contact with their invaders. But the discovery of these soils has led to renewed interest in the science of biochar and the technology to produce it.
So what is it about biochar that makes it such a super soil amendment? To answer that question, we need to first understand how it is made.
Biochar is simply wood that is exposed to high heat in a low oxygen environment – a process known as slow pyrolysis. This causes two important effects. One is that carbon-based molecules in the wood are converted to forms that are highly resistant to microbial decay. That means that char is unavailable as a food source to decomposers and remains in the soil for millennia rather than being gradually converted to CO2 through microbial respiration in a few decades.
The second effect of slow pyrolysis is that the cell structure of the wood remains intact. This creates a myriad of tiny compartments that provide pores for water storage and habitat for beneficial microbes. This also creates a huge surface area of black carbon that tends to adsorb soil minerals that would otherwise leach from the soil. This significantly increases soil productivity and boosts plant growth, thereby removing even more CO2 from the atmosphere.
So – biochar production 1) improves soil productivity, 2) converts logging slash into a value-added product, 3) creates jobs, 4) reduces fuels, and 5) removes carbon from the atmosphere and stores it in a stable form.
Given the urgency of all of the issues biochar addresses, it’s no surprise that there are groups of biochar enthusiasts springing up around the world. We are lucky to have a very active group of biochar champions in the Umpqua: the Umpqua Biochar Education Team (UBET). This dedicated crew of researchers and practitioners holds regular demonstrations – you can follow their activities at http://ubetbiochar.blogspot.com/.
The Yew Creek Land Alliance (YCLA), a local nonprofit with 380 acres of conifer forest and oak savanna west of Riddle, OR, recently completed a biochar project funded by the Natural Resources Conservation Service (NRCS) to treat six acres of logging slash left from oak habitat restoration/fire resiliency work completed this spring. Kelpie Wilson (http://www.wilsonbiochar.com/), a regional leader in biochar engineering and logistics, provided expert consulting services, and Mark Eason handled the contracting and some of the excavator work. We are extremely pleased with the results of the project!
We had a crew of 5-6 in the field for 12 days and treated over 6 acres. We first spent 2 days with a shovel operator using a “rake” to get the slash into piles near the road beforehand. We used 3 kiln styles: 5’ X 5’ Oregon Kilns (designed by Kelpie) (1.5 yards), a ~7′ diameter 4′ high round kiln similar to local biochar pioneer Don Morrison’s design (~5.5 yards), and 6′ X 13′ X 3.25′ rectangular kilns made from salvaged steel “boxes” from old 39″ X 79″ flat plate solar panels (9+ yards).
All of these kilns are designed to utilize a “flame cap” that uses smaller fuels to char larger diameter wood. In contrast to the way you would build a fire in your wood stove or fireplace, the larger fuels were loaded at the bottom of the kiln and the fine fuels on the top. We lit the initial fires with propane burners so that we could get an even, clean-burning flame across the whole surface of the kiln. This prevents the downward flow of oxygen into the deeper parts of the kilns while providing heat in excess of 2000o F on top resulting in the slow pyrolysis of the larger material.
We found all 3 kiln styles to be effective in particular situations: we set up the big kilns on the roads near big slash piles, the round one in uneven, off-road settings with a lot of slash nearby, and we used the Oregon kilns to “clean up” in the spaces between. In areas of the project that were too far from the water truck or otherwise difficult to access or process, we left the slash in small scattered piles for wildlife.
Our preliminary results indicate that we converted 20-30% of that slash into biochar, and the whole project came in under-budget. And, yes, the area now looks like a park instead of a post-logging war zone!
We will be treating another 6 acres of slash produced during more restoration work on the YCLA property in 2019, and we will be inviting the public up to see it. Stay tuned to future issues of 100 Valleys and Watershed Moments for times and dates of our next biochar project/demonstration. In the meantime, follow the inks above to learn more about bringing this vital ancient technology back to local ecosystems.