To curb the archaeological destruction in Brazil and improve agriculture production worldwide, researchers have come up with a modern method of creating this black magic earth. Take some normal soil, add a handful of charcoal, a bunch of leaves and a dollop of cow poop. You've got modern-day terra preta, called bio-char. "Bio-char has these very efficient properties of retaining nutrients. It will retain more carbon in the soil better than any uncharred organic matter," Lehmann said.

The search for El Dorado in the Amazonian rainforest might not have yielded pots of gold, but it has led to unearthing a different type of gold mine: some of the globe's richest soil that can transform poor soil into highly fertile ground. That's not all. Scientists have a method to reproduce this soil -- known as terra preta, or Amazonian dark earths -- and say it can pull substantial amounts of carbon out of the increasing levels of carbon dioxide in the Earth's atmosphere, helping to prevent global warming.

It shouldn't be there, but it is. terra preta, which may cover 10 percent of Amazonia, was the product of intense habitation by Amerindian populations who flourished in the area for two millennia. What researchers find most remarkable is that instead of destroying the soil, the indigenous inhabitants improved it - something ecologists don't know how to do today.

The intricate recipe used for producing these fertile soils has been the object of longstanding scientific curiosity.