Terra preta (which means "dark soil" in Portuguese), refers to expanses of very dark soils found in the Amazon Basin. It is also known as "Amazonian dark earth" or "Indian black earth". In Portuguese it's full name is Terra preta do indio or Terra preta de indio. Amazon River basin The Amazon Basin is the part of South America drained by the Amazon River and its tributaries. ...

Terra preta is distinguished from terra comum, or "common soil", which refers to the reddish or yellowish ferralsols that predominate under tropical soils. The soil is believed to be the result of past indigenous activities in the forest and is thus considered to be anthropic and/or anthropogenic, possibly from a pre-Columbian civilization. Oxisols are an order in USA soil taxonomy, best known for their occurrence in tropical rain forest, 15-25 degrees north and south of the Equator. ... In physics and cosmology, the anthropic principle is an umbrella term for various dissimilar attempts to explain the structure of the universe by way of coincidentally balanced features that are necessary and relevant to the existence on Earth of biochemistry, carbon-based life, and eventually human beings to observe such... Anthropogenic effects or processes are those that are derived from human activities, as opposed to effects or processes that occur in the natural environment without human influences. ... The term Pre-Columbian is used to refer to the cultures of the New World in the era before significant European influence. ...

Composition of terra preta

Terra preta consists of low temperature charcoal, pottery shards, plant residues, animal faeces, fish bones, and perhaps some biological agent like a special ecosystem of healthy microorganisms. As it is very rich in nutrients to this day local farmers and caboclos in Amazonian basin seek it out for use as compost. Charcoal is the blackish residue consisting of impure carbon obtained by removing water and other volatile constituents from animal and vegetation substances. ... Shard, also called sherd or potsherd, is a term for broken pieces of pottery or glass, often used in archaeology. ... Rabbit feces are usually 0. ... An ecosystem, a contraction of ecological and system, refers to the collection of components and processes that comprise, and govern the behavior of, some defined subset of the biosphere. ... A microorganism or microbe is an organism that is so small that it is microscopic (invisible to the naked eye). ... A Caboclo is a person of mixed Brazilian Indian and European ancestry. ...

Origin of terra preta

For a long time, the origins of the Amazonian dark earths were not immediately clear and several theories were considered. One idea was that they resulted from ashfall from volcanoes in the Andes, since they occur more frequently on the brows of higher terraces. Another theory considered formation as a result of sedimentation in Tertiary lakes or in recent ponds. The Andes form the longest mountain chain in the world. ... Sedimentation describes the motion of particles in solutions or suspensions in response to an external force such as gravity, centrifugal force or electric force. ... Tertiary period was previously one of the major divisions of the geologic timescale, from the end of the Cretaceous period about 65 million years ago to the start of the Quaternary period about 1. ...

However, because of their elevated charcoal content and the common presence of pottery remains, it is now widely accepted that these soils are a product of indigenous soil management involving a labor intensive technique termed slash-and-char. The technique is differentiated from slash and burn by a lower temperature burn and in being a tool for soil improvement. Amending soil with low temperature charcoal produced from a mix of wood and leafy biomass (termed biochar) has been observed to increase the activity of arbuscular mycorrhizal fungi. It is theorized that terra preta self-propagates via this mechanism; a virtuous cycle established as the fungus spreads from the charcoal, fixing additional carbon and stabilizing the soil with glomalin, and increasing nutrient availability for nearby plants. Assarting in Finland in 1892 Slash and burn (a specific practice that may be part of shifting cultivation or swidden-fallow agriculture) is an agricultural procedure widely used in forested areas. ... |0. ... Biochar is a type of charcoal produced from biomass. ... An Arbuscular mycorrhiza (plural mycorrhizae or mycorrhizas) is a type of mycorrhiza in which the fungus penetrates the cortical cells of the roots of a vascular plant. ... Millions of years ago, trees, flowers and grasses faced many natural stresses, such as low soil fertility, drought and temperature extremes. ... In many parts of economics there is an assumption that a complex system of determinants will tend to lead to a state of equilibrium. ... This article needs to be wikified. ...

About 10% of the original terra comum appears to have converted to terra preta. Whether all Amazonian dark earth was intentionally created for soil improvement or whether the lightest variants are a by-product of habitation is not clear at present time. This is in part due to the varied features of the dark earths throughout the Amazon Basin. Thus suggesting the existence of an extensive ancient native civilization dating back 500 to 2500 years bp. Amazon River basin The Amazon Basin is the part of South America drained by the Amazon River and its tributaries. ... Before Present (BP) years are the units of time (counted backwards to the past) used to report raw radiocarbon ages and dates referenced to the BP scale origin in the year AD 1950 (identical to 1950 CE). ...

Product of an advanced pre-Columbian civilization?

The Portuguese explorer Francisco de Orellana, the 16th C explorer who was the first European to transverse the Amazon River, reported densely populated regions running 100's of kilometers along the river, suggesting population levels exceeding even those of today. While it is possible Orellana may have exaggerated the level of development among the Amazonians, their semi-nomadic descendants have the odd distinction among primitive societies of a hereditary, yet landless, aristocracy, a historical anomaly for a society without a sedentary, agrarian culture. This suggests they were once more civilized and agrarian but after the demographic collapse of the 16th and 17th century due to European introduced diseases they reverted to more primitive modes of existence but kept certain traditions. Moreover, many indigenous people were forced to adapt to a more mobile lifestyle in order to protect themselves against colonialism. This might have made the benefits of terra preta, such as its self-renewing capacity, less attractive — farmers would not have been able to enjoy the use of renewed soil because they would have been forced to move for safety. Slash-and-burn might have been an adaptation to these conditions. A Spanish postal stamp featuring Orellana Francisco de Orellana (c1500-c1549) was a Spanish explorer and conquistador. ... A satellite image of the mouth of the Amazon River, looking south The Amazon River or River Amazon (Spanish: ; Portuguese: ) of South America is the most voluminous river on earth, having a greater total flow than the next six largest rivers combined. ... The Ancient Greek term aristocracy meant a system of government with rule by the best. This is the first definition given in most dictionaries. ... Millions of indigenous people lived in the Americas when the 1492 voyage of Christopher Columbus began an historical period of large-scale European contact with the Americas. ... See colony and colonisation for examples of colonialism which do not refer to Western colonialism. ...

References

• Terra Preta Home Page. Cornell University. Retrieved on 2006-05-08.
• Terra Preta Home Page. School of Geosciences and Geography (Universität Bayreuth). Retrieved on 2006-05-08.
• Lehmann, J; Kern, D; Glaser, B; Woods, W: Amazonian Dark Earths: Origin, Properties, Management.
• Glaser, B.; Woods, W: Amazonian Dark Earths: Explorations in Space and Time.

2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... May 8 is the 128th day of the year in the Gregorian Calendar (129th in leap years). ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... May 8 is the 128th day of the year in the Gregorian Calendar (129th in leap years). ...

Further reading

• Eprida Home Page. Retrieved on 2006-05-08.
• Programme Summary: The Secret of El Dorado. BBC Two, 9pm, Thursday 19 December, 2005. Retrieved on 2006-05-08.
• Terra Preta. Hypography discussion forum. Retrieved on 2006-05-08.
• Putting the carbon back: Black is the new green. Nature. Retrieved on 2006-09-20.