Great article Michaelangelica. The idea that ancient Amazonians terraformed vast areas using a sustainable agricultural model shows a possible degree of sophistication and stewardship that is sadly lacking today. The big question is whether this system is reproducible, as well as exportable, and can be adapted by modern farmers. My guess is that it can, that there is nothing about the Terra Preta process that is unique to the tropics. Some of the literature seems to support this too.
The process I'm working on is to replace most or all of the "browns" in one of my compost piles with low-heat charcoal. I've decided to stick with woody material (fruit tree prunings, alder and maple branches) with the idea that most of the ADE charcoals were probably made from the hardwoods originally cleared to make the sites. I'm running this material through a chipper to make it easier to fit into a stovepipe for cooking.
The literature suggests that additional N will need to be added to the system until an equilibrium is reached. This makes sense in terms of normal composting, as wood chips used as browns tend to tie up N until decomposition is complete, then release it back to the soil. To accomplish this, I am adding more clover than usual to my compost mix. This past weekend I got a pile started that's 42 by 42 by 36 inches, but have only just started adding the charcoal.
As for making the charcoal itself, so far I have only been using material I've gleaned from a couple of old brush burning piles, but have plans under way to build an eight foot wide solar trough. In the mean time, I thought I'd try making a batch in a 4 inch stovepipe by laying it in the side of my wood-fired steel barrel barbecue when we cook diner tonight.
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