Biochar and the Victorians

Late 19th century charcoal-making

I love anachronisms. The idea that a technology might have been invented long ago, ‘before its time’, and only rediscovered recently, has a great sense of mystery to it. When one comes across such apparent ‘anachronisms’ (like the ancient Greek computer, for instance, or Leonardo da Vinci’s design for a parachute), it is also, I feel, a vindication of timeless human ingenuity: people have always been technically adept, long before the industrial revolution.

So when I first heard about biochar – the charcoal soil amendment which is now being touted as a means of carbon sequestration and way of boosting crop yields – I was both excited and suspicious. Excited, because biochar does seem to be a very promising technology, capable of tackling the twin challenges of climate change and food production. Suspicious – because, as such a low-tech, ‘appropriate’ technology, I was sure someone must have invented biochar before. Though global warming is a relatively recent spur to invention, growing more food where less grew before is the oldest of human necessities.

As it happened, modern biochar research had grown out of archaeological finds in South America: the discovery in the 1960s of the Amazonian Dark Earths, soils with a very high carbon content that had been created by long-lost civilisations with a profound knowledge of how to cultivate poor tropical soils. But reading the rather romanticised accounts of these civilisations, I felt there had to be more. You don’t need to be a long-lost Amazonian civilisation to know how to make your veg patch grow better. After all, biochar is only essentially charcoal by another name, and charcoal has been made and used in Europe (and most other centres of settlement) for thousands of years. My hunch was that others had also hit upon its agronomic properties. So I checked out some Victorian gardening almanacs, and lo and behold, a number referred to charcoal’s utility as a manure. More interestingly, some authors seemed to come up with the same explanations for these properties as modern soil scientists. Ransacking the shelves of second-hand bookshops, I scoured gardening manuals from the mid-19th century through to the early organic pioneers of the 1950s, discovering a welter of examples of biochar use long before it became fashionable. The resulting study can be downloaded as a PDF below.

Unearthing the past GShrubsole Nov 2010

So what?, you might ask. The fact that biochar has been used by some gardeners and farmers for centuries doesn’t mean it was widely used; nor does it of course negate the need for modern experiments to better understand biochar’s properties. But the existence of historical precedent might make us, firstly, a little more confident that biochar really might work; secondly, a little more humble, in that others have cracked the idea before; and thirdly, a little more attentive to the wisdom of our ancestors.

I’ve got a few old documents relating to early biochar research that I’ll be scanning in, so will return to this subject again in a future post – particularly to argue why the Soil Association ought to be promoting biochar more than it does.