Just as the wildfires in California were raging most ferociously this week, I picked up New Scientist magazine and learned something that probably offers no consolation whatsoever for the scorched earth many Southern Californians are now confronting: It’s possible to burn a landscape in a way that yields something extremely valuable. It’s called biochar, the end product of slowly combusting organic matter in an oxygen-poor environment.
Biochar seems to be a key ingredient of terra preta, the super-fertile soil of the Amazon created by some very smart pre-Colombian gardeners. Now biochar could conceivably help us to stop cooking the earth, because the charring process can be used to generate biofuels or electricity. Meanwhile, the leftover char locks up carbon underground almost indefinitely–carbon that might otherwise make its way into the atmosphere. At the same time, it encourages the robust growth of plants, which, in turn, take CO2 out of the air and turn into oxygen.
In fact, an article in Nature says that a number of scientists are extremely interested in biochar as a means to combat global warming:
Johannes Lehmann of Cornell University in Ithaca, New York…estimates that by the end of this century terra preta schemes, in combination with biofuel programmes, could store up to 9.5 billion tonnes of carbon a year — more than is emitted by all today’s fossil-fuel use.
Organic matter that’s smoldered rather than burned is much better at locking in carbon and creating a long-term positive change in the quality of the soil. Still, I’ve long scattered the detritus of my fireplace–a mix of ash and charcoal–underneath my lilacs and clematis to make the soil more alkaline for them, and noticed how cheerful they look about it.
The Nature piece also mentions the work of Danny Day, the entrepreneur who founded a company called Eprida, which makes equipment for generating biofuels and biochar.
Originally, Day was mostly interested in making biofuel; the char was just something he threw out, or used to make carbon filters. Then he discovered that his employees were reaping the culinary benefits of the enormous turnips that had sprung up on the piles of char lying around at the plant.
Now Day is making a biochar-heavy fertilizer, too. I always love a story in which food-obsessed vegetable gardeners drive technological progress across the globe.