Hello, This is my first posting to this blog. I just listened to Jason Bradford's reality report of August 21. During the report the subject of Terra Preta came up, and one of the callers asked whether Terra Preta was a product of slash and burn agriculture, a practice that contributes to the very release of sequestered carbon that the use of Terra Preta was presented as countering to some extent. Cornell University has been studying the origins of Terra Preta in the Amazon rain forest. From what I have read the consensus seems to be that, at least in part, Terra Preta is the result not of slash and burn but of slash and char agriculture. In slash and burn agriculture, fallow or primary forest biomass is cut and burned to allow planting of crops. The ash resulting from the burn helps to sustain a few cropping cycles before the land has to revert back to fallow. In a slash-and-char adaptation of this shifting cultivation system, the identical amount of biomass is used, but instead of being completely burnt, about 50% of the biomass carbon is retained as charcoal and added to the soil. Lonnie Brown Albuquerque, New Mexico