Literature: a few references that may interest you...

1. A. Downie, Crosky, A., Munroe, P., 2009, Chapter 2: Physical Properties of Biochar, in J. Lehman and S. Joseph (eds), Biochar for environmental management, Earthscan, London.
2. K. Y. Chan, Van Zwieten, L., Meszaros, I., Downie, A., and Joseph, S., 2007, Agronomic values of greenwaste biochar as a soil amendment, Australian Journal of Soil Research, 45, 629–634.
3. J. M. Kimetu, Lehmann, J., Ngoze, S.O., Mugendi, D.N., Kinyangi, J.M., Riha, S., Verchot, L., Recha, J.W., and Pell, A.N., 2008, Reversibility of Soil Productivity Decline with Organic Matter of Differing Quality Along a Degradation Gradient, Ecosystems, 11:5, 726-739.
4. J. Lehmann and Joseph, S., 2009, Chapter 1: an Introduction, in J. Lehman and S. Joseph (eds), Biochar for environmental management, Earthscan, London.
5. L. Van Zwieten, Singn, B., Joseph, S., Kimber, S., Cowie, A., Chan, Y., 2009, Chapter 13: Biochar and emissions of non-CO2 greenhouse gases from soil, in J. Lehman and S. Joseph (eds), Biochar for environmental management, Earthscan, London.
6. J. Lehmann, Gaunt, J., and Rondon, M., 2006, Bio-char sequestration in terrestrial ecosystems- A review, Mitigation and Adaptation Strategies for Global Change, 11: 403–427.
7. Edinburgh Biochar Research Centre. http://www.biochar.org.uk/ukbrc_introduction.php
8. E. Marris, 2006, Black is the New Green, Nature, Vol. 442.
9. N.C. Brady and Weil, R. R., 2008, An Introduction to the Nature and Properties of Soils, 14th ed. Prentice Hall, Upper Saddle River, NJ, USA.
10. K. Carmichael-Timson, 2006, The majical soils of El Dorado, Permaculture Magazine, Vol. 50.
11. J. E. Thies and M. C. Rillig, 2009, Chapter 6: Characteristics of Biochar: Biological Properties, in J. Lehman and S. Joseph (eds), Biochar for environmental management, Earthscan, London.
12. J. Lehmann, in press, ‘Terra preta Nova – where to from here?’, in W. I. Woods, W. G. Teixeira, J. Lehmann, C. Steiner and A. WinklerPrins (eds), Terra preta Nova: A Tribute to Wim Sombroek, Springer, Berlin.
13. W. Sombroek, Ruivo, M.L., Fearnside, P.M., Glaser, B. and Lehmann J., 2003, ‘Amazonian Dark Earths as carbon stores and sinks’, in J. Lehmann, D.C. Kern, B. Glaser and W.I. Woods (eds.), Amazonian Dark Earths: Origin, Properties, Management, pp. 125–139 , Kluwer Academic Publishers, Dordrecht.
14. S.P. McGrath, Loveland, P. J., 1992, The soil geochemical atlas of England and Wales, pp. 101.