The inspiration for the supplementation of soil with charcoal stems from observations made
in the ancient agricultural management practices that created terra preta, deep black soils.
These soils, found throughout the Brazilian Amazon, are characterised by high levels of soil
fertility compared with soils where no organic C addition occurred (Harder, 2006; Marris,
2006; Lehmann, 2007a; Renner, 2007). The evident value of the terra preta led to the
suggestion that investment into biochar and application to agricultural soil may be both
economically viable and beneficial. Rising fossil fuel prices, the need to raise yields in light of
the global food crisis, and the emergence of a significant global market for trading carbon
appear to promise added economic incentives in the future.