Thursday, February 19, 2009

Biochar - a magic bullet?

Today, as often happens, I got carried away in my reading about matters relevant to climate change and peak oil. The trail started with an article I ripped out of The Independent a few weeks ago about how burying charcoal could be an effective way both to sequester carbon and increase the fertility of soil. I first looked up "biochar" in Wikipedia, then "terra preta" (terra preta is the fertile, black soil found on land inhabited in former centuries by Amazonian Indians) and that led me to an article from Nature (2006) entitled Black is the new green. As it happens, the Independent article is about an initiative involving Craig Sams, one of the founders of Green & Black's chocolate.

According to the Nature article, burying charcoal offers a triple gain - as well as sequestering its own carbon and improving soil fertility, the charcoal provides a favourable environment for living organisms within the soil so causing even more CO2 to be captured. It all looks too good to be true but I have no good reason to be sceptical.

For permaculturalists, who prefer not to till the soil but to plant directly, there is a problem - how do you bury the charcoal? No doubt someone will come up with an answer. How do I know about permaculturalists? I have just read Permaculture in a nutshell by Patrick Whitefield - a very slim volume but it seems like an excellent introduction to the subject leaving me eager to learn more.

While reading particularly the Wikipedia articles I was glad that I had recently taken steps to fill some appalling gaps in my scientific education. Until just over a year ago I knew very little about chemistry, never having studied it at school. My first activity following my giving up paid work was to take the Open University Discovering Science course (S103, since replaced by S104, Exploring Science). I can't call myself a scientist on the basis of that one eight-month course but I now feel a lot happier reading science literature.

More on coppicing

The day before yesterday I spent half a day doing a free taster course on coppicing at the Brinsbury campus of Chichester College, between Billingshurst and Pulborough, West Sussex. I have now been actively coppicing and pollarding for the last six weekends, interspersed with pruning (ie cutting up to six-inch thick branches off) apple trees.

The course reassured that what I was doing was broadly right and gave me some extra guidance on various points. I was particularly interested in how to protect the "stools" (what is left after coppicing) from deer. At Brinsbury they build little "wigwams" of brushwood over the stool. The wigwam erected by a fellow student and myself is probably more elaborate than is necessary but it was fun to build and reminded me of my one-time life as an architect.