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Unformatted text preview: In the 1950s, early in his career as a soil scientist, Sombroek journeyed to Amazonia. To his amazement, he found pockets of rich, fertile soil. Every Ecology 101 student knows that Amazonian rain forest soils are fragile and impoverished. If farmers cut down the canopy of trees overhead to clear cropland, they expose the earth to the pummeling rain and sun, which quickly wash away its small store of minerals and nutrients and bake what remains into something resembling bricka "wet desert," as these ruined areas is sometimes called. As lush and dark as the plaggen of his childhood, it formed a rich base for agriculture in a land where it was not supposed to exist. Terra preta is found only where people lived, which means that it is an artificial, human-made soil, dating from before the arrival of Europeans. The soil is rich in vital minerals such as phosphorus, calcium, zinc, and manganese, which are scarce in most tropical soils. But its most striking ingredient calcium, zinc, and manganese, which are scarce in most tropical soils....
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This document was uploaded on 11/02/2011 for the course BIOLOGY Bi 105 at Montgomery.
- Spring '11