Deep in the Amazon jungle, scientists have found soil called terra preta, thousands of years old, made from human waste that's still fertile for growing crops today! Everything ancient civilizations used went into a midden heap after they were done with it - pottery, fish bones, food scraps, human waste - and then once it was burned, the midden created such valuable soil that it's still thriving at least 3,000 years later.

What a different waste management system the ancients had, compared to our toxic landfills and incinerators of modern times. But, the ancients never had to deal with plastic.

Biochar is charcoal made from organic matter instead of charcoal from fossil fuels, and it has some surprisingly valuable uses. Tom Miles is the Executive Director of U.S. Biochar Initiative, Chair of International BioChar Initiative, and the president of TR Miles Technical Consultants Inc., and he joins the show from Portland to talk all about biochar and healthy soils.

If you're interested in building your own healthy soil this episode is for you!

Ken Burns' Dust Bowl documentary on PBS