Superdirt Made Lost Amazon Cities Possible?

                                       Superdirt Made Lost Amazon Cities Possible?






John Roach
for National Geographic News
November 19, 2008

Centuries-old European explorers' tales of lost cities in the Amazon have long been dismissed by scholars, in part because the region is too infertile to feed a sprawling civilization.

Now scientists are trying to recreate the recipe for the apparently human-made supersoil, which
still covers up to 10 percent of the Amazon Basin. Key ingredients included of dirt, charcoal, pottery, human excrement and other waste.

If recreated, the engineered soil could feed the hungry and may even help fight global warming,
experts suggest.







Before 1492



Scientists have long thought the river basin's tropical soils were too acidic to grow anything but the hardiest varieties of manioc, a potatolike staple.

But over the past several decades, researchers have discovered tracts of productive terra preta—"dark earth." The human-made soil's chocolaty color contrasts sharply with the region's natural yellowish soils.