National Geographic — Our Good Earth: The future rests on the soil beneath our feet.
The September 2008 issue of National Geographic has an article on soil that contains an extended discussion of biochar — beginning on page 7 [of 9]:
Sombroek had wondered if modern farmers might create their own terra preta—terra preta nova, as he dubbed it. Much as the green revolution dramatically improved the developing world’s crops, terra preta could unleash what the scientific journal Nature has called a ‘black revolution’ across the broad arc of impoverished soil from Southeast Asia to Africa.
Key to terra preta is charcoal, made by burning plants and refuse at low temperatures. In March a research team led by Christoph Steiner, then of the University of Bayreuth, reported that simply adding crumbled charcoal and condensed smoke to typically bad tropical soils caused an ‘exponential increase’ in the microbial population—kick-starting the underground ecosystem that is critical to fertility.