Erich,
Interesting exchange over at RealClimate. Glad to see your post there - does the Beyond Zero Emissions link work OK? I get a page not found shown. The Dominic Woolf paper from January 2008 has some interesting details in it, and provides a good basis to discuss specific advantages and challenges. There are quotes in it about soil stability for 6000+ years and mentions of various Lehmann papers. I suppose one conclusion is that more research would be helpful to see how well TP can help in a variety of environments. One can easily follow the overall discussion in the thread by searching for "biochar".
RealClimate
And here is a link to the Dominic Woolf paper:
New report available online: "Biochar as a Soil Amendment - A review of the Environmental Implications" | Terra Preta
Steve
