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Superdirt Made Lost Amazon Cities Possible?

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Author Topic: Superdirt Made Lost Amazon Cities Possible?  (Read 172 times)
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« on: November 22, 2008, 05:26:40 pm »

Left - a nutrient-poor oxisol;

right - an oxisol transformed into fertile terra preta

                                                     T E R R A   P R E T A

From Wikipedia, the free encyclopedia

Terra preta (“dark earth” in Portuguese) refers to expanses of very dark, fertile anthropogenic soils found in the Amazon Basin. It owes its name to its very high charcoal content. It is also known as “Amazonian dark earth” or “Indian black earth”. In Portuguese its full name is “Terra preta do índio” or “Terra preta de índio”. Terra mulata is lighter or brownish in color.

Terra preta is characterized by the presence of low-temperature charcoal in high concentrations; of high quantities of pottery sherds; of organic matter such as plant residues, animal faeces, fish and animal bones and other material; and of nutrients such as nitrogen (N), phosphorus (P), calcium (Ca), zinc (Zn), manganese (Mn).

It also shows high levels of microorganic activities and other specific characteristics within its particular ecosystem. It is less prone to leaching than surrounding soils. Terra preta zones are generally surrounded by terra comum, or "common soil"; these are infertile soils, mainly acrisols, but also ferralsols and arenosols

Terra preta soils are of pre-Columbian nature and were created by man between 7000 BP (ca. 5000 BC) and 500 BP (ca. 1450 AD) ("Before Present"). The soil's depth can reach 2 metres (6 feet). Thousands of years after its creation it is reputedly known as self-regenerating at the rate of 1 centimetre per year by the local farmers and caboclos in Brazil's Amazonian basin, and they seek it out for use and for sale as valuable compost.
« Last Edit: November 22, 2008, 05:31:17 pm by Bianca » Report Spam   Logged

Your mind understands what you have been taught; your heart what is true.

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