Biochar Experiment

An email arrived this week from a company called Oxford Biochar. I had forgotten that some time ago I volunteered to take part in a biochar trial. They tell me they are posting out the kits and instructions very shortly. Few details yet of what is expected of us but I am pleased to get the chance to be involved in a trial of this kind.

Most people who are likely to come across this blog will be aware of biochar and what is claimed of it. Fewer, I imagine, will be using it or have any experience with it. I don't want to run through the whole history, the claims of its proponents or the scepticism of its detractors. (Some of the most informative sources I have come across about biochar are listed here.) But when you have lots of noise and little action, there is nothing better than getting your hands dirty to help provide some evidence.

It seems to me there are two distinct sets of criteria to consider when using biochar. The first is strictly from a gardening viewpoint: is it effective in conditioning soil and enhancing plant growth in organic systems? Under this heading we might include: improved moisture retention, reduced soil acidity, reduced leaching of nutrients, reduced fertiliser requirement, increased availability of nutrients and so on. The second aspect is biochar's potential for carbon sequestration. Under this heading we might include: projected contribution to reduction of global carbon emissions; the economics and environmental aspects of biochar production; stoves, methods of pyrolysis, gasification and recoverable energy, and so on.

If positive conclusions can be arrived for both aspects - then it seems we are on a winner. Can it be a solution to global warming and boost our productivity in organic systems? Many say so but some biochar growing trials are inconclusive or report negative results. And what if governments thought it would be a good idea to give subsidies to farmers to grow crops for turning into charcoal instead of feeding people?. Biofuel seemed a good idea when it was made from the waste from sugar plantations in Brazil but not so clever when the economics made it profitable to use the whole plant and not just the waste.

Important as the second question is, it is the experience of gardeners and farmers that can shed light on the first question. Can we replicate the presumed benefits of the terra preta soils of Brazil? Do improvements in plant productivity only occur on poor-quality soils? To what extent does biochar have to be 'primed' before using? What differences are produced in biochars by varying the temperature of pyrolysis? To what extent does the nature of the source material effect the action and qualities of the end product?

When my package arrives from Oxford Biochar it may just be a small bag of charcoal, a few seeds and an instruction sheet. But even with those modest assets I hope to make a small contribution to a field with many questions and few answers so far. I'll be recording my progress with the experiment on the blog. Please follow!

Screen grab from Oxford Biochar video