A couple of Tuesdays ago, I gave a talk at the Merritt College Horticulture Department, in their Design Forum. The talk was centered around how to create an urban farm in a typical residential yard, as we have done here. It was a great night, filled with interesting questions from the audience, and as usual, I not only doled out some learnin’, I also received some learnin’. Every conversation I have with gardeners or farmers leaves me with new impressions and new knowledge, and then, of course, new questions.
One audience member asked me if I had any experience with biochar. The short answer was no. The slightly more detailed answer is that I’ve done some reading about it, and watched some educational videos from Living Web Farms about how to make it and apply it to your garden. I’ve also heard some negative things about it - that it’s a hoax - and I also have had some reservations about the way it is made; I have worried that the process of creating the biochar is actually releasing a lot of carbon into the atmosphere. The student who asked the question showed me some pictures from her own garden, of plants grown side by side, with and without biochar. Looking at those pictures, it was clear that there was a difference in the size, health, and production of the plants that grew WITH biochar. This intrigued me and I wanted to source some biochar of my own to try.
As my friend Lawrence likes to say, serendipity is everywhere, and that same night I happened to pick up a free copy of the fall edition of Edible East Bay magazine (which they make available in the Hort Dept), which I always enjoy and learn a lot from. And wouldn’t you know it, there inside was a huge article about biochar, and a story about a company that makes it in Berkeley (All Power Labs, more on them in a minute) and a community farm, Gill Tract, that has been trialing the biochar in their compost and raised beds systems. Well. I immediately contacted the lab and signed up for a year’s subscription of biochar. Today I went to pick up the first batch, and was absolutely blown away by the welcome I received from Aidin at All Power Labs, who then spent a good deal of time showing me around the joint and explaining the process of how biochar is made. He also welcomed me to the Local Carbon Network, which is a “community-powered local drawdown network.” I love this and I love that I’m a part of it, officially, though honestly I’ve been a part of it for years. :)
At the end of my visit, I mentioned Merritt and said that the Hort Dept should do some trials of their own with this product, and Aidin said, “What a coincidence, my coworker Austin is giving a presentation at noon at Merritt,” which turned out to be in my friend Lawrence’s permaculture class! I texted Lawrence and asked if I could drop in and hear the lecture and he kindly allowed me to do that, and I got to hear the details all over again (and take notes this time) which really helped cement the ideas in my brain. More serendipity!
So, here’s the scoop. All Power Labs was originally created to make renewable energy using biomass. That is, make power by burning the waste products of agriculture or even our urban yards - tree trimmings, wood chips, etc. In the process of making this renewable energy, a by-product was produced - bits of what looked like charcoal, very light and made of pure carbon. Originally they just threw this product out. Then they realized it was biochar, and high quality biochar at that, and that it was a coveted resource for farmers and gardeners, as it does a lot of cool things in the soil (which I will detail in a bit). The original purpose of the company, making renewable energy for use, was having trouble finding a niche in the very large solar and wind energy economy we have in California. So, they pivoted a little into the biochar side of things.
Shortly after that, they partnered with Gill Tract farms to do some trials and figure out how this stuff really works. Bob Flasher at the farm has been working closely with APL and seems to be quite sold on how the char performs in his garden and has documented how the plants perform. Knowing that he has been an early adopter of the char helps me to feel good about moving forward, trying it in my own yard.
Now more about the process. Above is a photo of the “Powermass Gasifier” which is the machine that turns biomass into both energy and biochar. The energy now is used to run the machine, so it’s a closed loop - no emissions or volatiles are escaping into the atmosphere. In fact, the carbon that is trapped in the biomass is turned into a product which can help sequester carbon into the soil. At this point, you might be saying, “Well, doesn’t compost do that too?” and the answer is yes, it does. It helps feed the microbiology which are turning the compost into humic acids in the soil, which do sequester carbon. There are some problems with compost, though, which you might have experienced (I know I have). One, it doesn’t last more than a season. I put a couple inches on my beds each fall, and by early summer, the beds look like they never had it. The soil surface is quite low, several inches below the top of the wooden beds. What happened to the compost? Well, some was turned into nutrients for the plants by the microbiology in the soil. Some, however, was off-gassed, releasing carbon into the air again as it decomposes further. Compost does continue to decompose, it doesn’t stop just because you’ve moved it to your veg beds.
walnut hulls, an abundant waste product from California orchards, which will be turned into biochar
Biochar doesn’t decompose. It’s already been processed into its permanent form - pure carbon. This happens in the process of Pyrolysis. The volatile carbon in the biomass is burned off (and used for energy), and what is left is like the embers of a campfire. Totally indestructible, permanent bits of carbon.
These bits of carbon, if applied to a garden/farming system, become hosts for a ton of microbial life. They absorb humic material. They have a very high CEC (cation-exchange capacity) which means that they add nutrient density to the soil. It improves drainage (tilth) while helping with water retention, as they can absorb many times their size in water. They improve friability of soil. They store the mineral nutrients from biological processes. They even, apparently, bind heavy metals and immobilize pollutants.
These are the composter tumblers that they are using at All Power Labs to do their own trials with biochar. And Aidin was clear that they recommend that we compost biochar first, not just add it directly to planting beds. There the biochar will be inoculated with the microbia of the compost pile and start to do work. There is a lot of evidence from Gill Tract Farm that adding biochar also increases the temperature of compost piles by quite a lot (this is something I desperately need). Not only that, Gill Tract has seen the temperature spike and then remain at high temperatures for six weeks after an application of biochar! I’m hoping to see this in my own compost piles. I came home with a large bucket of char, and added only a cup to the worm bin and about 10 cups to the large compost pile in the chicken run (they recommend adding 10% biochar by volume, an estimate is ok. My bucket should last three months). We’ll see how that works to activate heat and decomposition.
I also really appreciate that the biomass used to make this biochar is nut hulls from California orchards. This is taking something out of the waste stream, something that takes hundreds of years to decompose, and putting it to good use.
If you’re interested in your own subscription of biochar and live in the area, you can contact Aidin at The Local Carbon Network. It’s not cheap, I’ll warn you now, but I imagine that in time, when the benefits of biochar are documented and realized, the price will level out. I also believe it is worth it, if it will help me process enough compost to add two inches to all of my planting beds once a year. This would be terrific because I’m tired of buying compost, for many reasons: price (a lot more than this biochar), the unknown ingredients and their provenance, and the work/energy to get it here. So I’m invested in trying it to see if I can start to produce more compost here, in my yard.
To learn more about biochar, another good resource is the book Kiss the Ground , which is also, I believe, a movement that is part of the Marin Carbon Project.
The back of All Power Labs, which I just love. So Berkeley!
Have you tried making or using biochar? If so, I’d like to hear about it!