The term terra preta specifically applies to the Brazilian soils of the Amazon basin, where it was produced 5000 years ago, by an as yet uncertain agricultural process of ‘slash, burn and bury’ . This formed “reefs”, for the micro-organisms to colonise, and also stored nutrients against leaching in the high rainfall. Geoff Moxham writes…
Terra Preta…Jagabar Jagun… and a Carbon-Negative Future.
by Geoff Moxham
Terra preta translates as just ”black earth”, and perhaps here I should call it jagabar jagun, in the local bioregion’s ancestral language, and get over Amazonialism. (Bundjalung: black earth, Macquarie Ab.Dict.).
A few weeks ago on the ABC’s Catalyst , readers may have seen the aerial footage that only recently revealed the rows of cultivation, covering twice the area of the UK. This supported a huge population, the El Dorado that historians had first thought Spanish explorer Francisco de Orellana had hallucinated in 1542 . Remarkably, this soil is still fertile, and millions of tonnes of carbon appear to be genuinely sequestered as well, not just in a political fantasyland projection. Carbon dating is a rather well proven science, giving irrefutable proof of sequestration that even a lying rodent couldn’t ague away. But how can we ever know the real truth of how the Amazonians were doing it? The answer is doesn’t matter. This is a wonderful example of do local and think global. Composting with charcoal hasn’t really had much of a consciously devoted following before “terra preta” hit the media, though there is evidence the practice has also been in Japanese agriculture for some time. That the char is still there, is the evidence the fires were extinguished before the carbon started to burn, just like the blacksmith charcoal burners of Europe, and the Catalan forges of the Middle East. Presumably a shallow row-pit and smothering could combine with plowing energies, but water could have been used. However, as country dwellers will note, large, hot burn-offs kill the biota immediately below, for a long time so separate cool-burn sites would have become self-evidently essential.
Although we can’t really know how the S Americans processed terra preta due to lack of historical records, the char is the same, apart from the species of woody material. Locally, Peter Hardwick has started Biochar experiments at Djanbung using dried lantana and Crofton stalks, and Dr Keith Bolton intends to char his agricultural hemp waste, and reuse it. The way forward is to make your own from your own woody waste. This same waste, if composted, would return to the atmosphere as CO2 within about 3 years, whereas Biochar sequesters 30 -50% for thousands of years. The triple whammy of being a fertiliser, a long term carbon sequestration, and a renewable fuel qualifies it for Permaculture’s triple use bottom line, hence David Holmgren and other’s interest. It explains the glowing opening address by Tim Flannery at the first International Biochar conference at Terrigal, this year.
To smoulder or to pyrolise?
The temperature of this burn is critical to the efficiency of the conversion to charcoal. On one hand the technique of the Amazonians is being called smouldering , and on the other, modern techniques of charring are called pyrolysis.
Pyrolysis is really scientific jargon for burning, but is now increasingly being used to describe decomposing biomass with heat, in a reducing (low/zero oxygen) environment. This uses advanced materials, like high temperature steels and refractory linings. It requires fairly complex (by Amazonian standards) process and control engineering, and recent advances in gas turbines, used for the power that can be extracted from the lower volatiles as they…well…burn off. 
As we know intuitively, burning has a wide range of temperatures, depending on ‘what’ is burning, be it a Myers store, or metho on your hand. In the case of wood, up to about 300C the carbon can’t reach ignition temperature (er… it can’t burn), but all the lower boiling point volatiles and some cellulose will flash off as “smoke”. This is called syngas or producer gas, after it is cooled, and the soot particulates filtered out.
If these volatiles are carefully reburnt at high temperatures, no creosotes, furans and other nasties escape…the disadvantage of “smouldering”. Smoke has good energy value. Have you ever lit a fire in a potbelly, and had the smoke suddenly go whumpff! And a big fireball and ash comes out all the orifices! I have done this, many times. It’s hilarious… if you’re out of singeing range. This is exactly the same as the effect in the film Backdraft. Open the door and add oxygen…whoompff. The same applies to wood-gasifiers running internal combustion motors for home power. Open the wrong porthole and the bursting plates do their job, hopefully somewhere out of range. 
The biology of black earths.
The char is just a high rise for what microbial life is already in the soil, so it’s how we do the processing of the char afterwards that is the hot area of research, right now. Char size up to 1cm has shown to work, but finer is better. Inoculants will be a big business with companies like Eprida trying to say their ACOSS inoculation of the “coral reef” is better than … whoever’s…
What also seems to be happening is an actual fight for the names and the proprietary rights etc (why aren’t I surprised?…quiet vomit…) The International Agrichar Initiative changed its name to the International Biochar Initiative. I recommend their site: http://www.biochar-international.org/aboutbiochar/articlesonchar.html
IBI is an international collaboration to do R&D&D&D urgently on Biochar, and the site has links to the best downloads on the net.
The simple answer seems to be that if you have Aussie char in Aussie soil…Aussie biota will move in. In Amazonia…Amazonian biota will move in. I’d be betting there are lots of organisms involved, too many to list, and that some are common, around the world. There are undoubtedly some major players like fungus, bacteria, micorrhiza, in their synergistic relationships, not only to the soil, but what crop is currently growing there. Then there are probably thousands of other possible Latin names to list here. Fortunately they aren’t patented…yet. Watch this space explode…and the lawsuits, unless sanity prevails. I note, with some regret, that one of the buyers of pioneer Australian company, BEST, is Union (Bhopal) Carbide.
While it is still a matter of research if this is a 3-year or 1000 year cycle, it’s looking like the positive effects happen in a very short time, and last for centuries. It’s a pity the research is delaying the actual plowing in of 2 x the area of the UK, but as most agricultural soils have been biologically destroyed, a massive inoculation will have to take place, and that better be the right inoculation.
Locally, Lukas van Swieten, at the Wollongbar DPI soil research station is doing impressive field trials now . You might have noticed Terania Creek’s Josh on that Catalyst grab of the gas emission study.
GHG reduction bonus.
The trials at Wollongbar and Cornell, show that char treated soils emit far less GHG’s, especially the active ones like methane (28xCO2) and nitrous oxide (300xCO2). Just how much more carbon-negative char can become is still under scrutiny, by a wave of interest that looks like being as great as last century’s development of fossil fertilisers. There’s some very bright sparks of hope here that may yet claim Branston’s prize for sequestering a billion tons in a year.
The best news is that the process downsizes to the backyard … you can pee on char, put compost juice on it, worm juice, put it in your composting toilet… the list and the number of permutations and combinations is impossibly long. And every location’s colonising biota will be slightly different. I think this will be the future of Jagabar jagun.
BSc., Ind. Arts (technology)
Anticopyright/copywrong, Sept 26th 2007
1. Rise portal on biomass. This page is the full quid.
Going carbon negative, many links. Last updated: 11/08/2007 Rick Davies
MIT the case for burying charcoal
Black is the new green (Nature, 2006)
IBI; sanity; top hit.
3. Smouldered earth
4. Nextterras gasifier pic
5. 900mile ute pic url
6. Corn pics
7. BBC’s historicals of El Dorado
8. Lukas Van Swieten’s Wollongbar trial; Ag. Today Feb. 07
Post Script: Geoff Moxham passed way a year after writing this article. His work is continued by local people he inspired and who share his passion for the earth and furthering the solutions offered by sustainable local production and use of biocar.