Jungle Nexus Reduxamus Olius "terra preta"

Outside Manaus, Brazil, Eduardo Neves, a renowned Brazilian archaeologist, and American scientists have found huge swaths of "terra preta." 

So-called Indian dark earth, land made fertile by mixing charcoal, human waste and other organic matter with soil.

In 15 years of work they have also found vast orchards of semi-domesticated fruit trees, though they appear like forest untrammeled by man. ..

http://www.washingtonpost.com/wp-dyn/content/article/2010/09/03/AR2010090302302.html