Terra preta

Terra preta (portugisisk for "sort jord") er en type meget mørk og frugtbar menneskeskabt jord (anthrosol), der findes i Amazonbassinet. Terra preta har et meget højt indhold af trækul, og er fremstillet ved at tilsætte en blanding af trækul, ben og husdyrgødning til den normalt relativt ufrugtbare jord i regionen. Terra preta er meget stabil og forbliver i jorden i tusinder af år.^[1]^[2]^[3] Det fulde navn på portugisisk er terra preta do índio eller terra preta de índio ("indianernes sorte jord"). Terra mulata ("mulatjord") er lysere eller brunlig i farven.^[4]

Terra preta er karakteriseret ved tilstedeværelsen af lavtemperaturkul i høje koncentrationer, store mængder potteskår og organisk materiale som planterester, husdyrgødning, knogler fra dyr og fisk samt næringsstoffer som nitrogen (N), fosfor (P ), calcium (Ca), zink (Zn) og mangan (Mn). Det har også et højt indhold af mikroorganismer. Jorden er mindre modtagelig for udvaskning, hvilket er et stort problem i de fleste regnskove. Terra preta-zoner er normalt omgivet af terra comum ("almindelig jord"), som er infertile jordtyper såsom acrisol, oxisol og arenosol.

Terra preta er af præcolumbiansk oprindelse og blev dannet af mennesker mellem 450 f.Kr. og 950 e.Kr.^[5]^[6] Terra preta-jorden kan have en dybde på op til to meter.

Terra preta-jord findes hovedsageligt i den brasilianske del af Amazonbassinet, hvor Sombroek et al.^[7] anslår, at de dækker et areal på mindst 0,1 til 0,3 %, eller 6.300 til 18.900 km² af området^[4]. Andre har dog anslået, at de dækker et areal på 10,0 % eller mere, svarende til Frankrigs areal.^[8]

Referencer

^ 2009, nature.com: The bright prospect of biochar Citat: "...According to archaeologists, the rich, black and fertile terra preta was created by adding a mixture of bone, manure and charcoal to the otherwise relatively infertile soil over many years. The charcoal – believed to be the key ingredient – is 70 times more concentrated in terra preta than in surrounding soils and is formed by heating biomass in an oxygen-poor or oxygen-free environment...."
^ http://www.abc.net.au/rural/news/content/201102/s3136085.htm Dr Johannes Lehmann. notes 9000 year old terra preta soils
^ 01 December 2020, cambridge.org: The geoglyph sites of Acre, Brazil: 10 000-year-old land-use practices and climate change in Amazonia Citat: "...Over the past 20 years, research on Amazonian Dark Earths—terra preta—has advanced our knowledge of ancient Amerindian landscape management practices, both in riverine bluffs and upland terra firme forests near Amazonia's main riverine routes (see McMichael et al. Reference McMichael, Palace, Bush, Braswell, Hagen, Neves, Silman, Tamanaha and Czarnecki2014a: fig. 1). The dark earths are anthropogenic, highly fertile soils created by centuries of soil mulching over the otherwise poor Amazonian latosols..."
^ ^a ^b [1] "Discovery and awareness of anthropogenic amazonian dark earths (terra preta)", by William M. Denevan, University of Wisconsin–Madison, and William I. Woods, University of Kansas.
^ E.G. Neves, R.N. Bartone, J.B. Petersen & M.J. Heckenberger (2001). The timing of Terra Preta formation in the central Amazon: new data from three sites in the central Amazon. s. 10.{{cite book}}: CS1-vedligeholdelse: Flere navne: authors list (link)
^ "Historical Ecology and Future Explorations" i Amazonian Dark Earths: origin, properties, and management "Arkivert kopi". Arkiveret fra originalen 2006-09-17. Hentet 2006-09-26. av J. Lehmann, N. Kaampf, W.I. Woods, W. Sombroek, D.C. Kern, T.J.F. Cunha et al., kapittel 23, 2003. (Clark Erickson), s. 484
^ «Classification of Amazonian Dark Earths and other Ancient Anthropic Soils» i Amazonian Dark Earths: origin, properties, and management "Arkiveret kopi". Arkiveret fra originalen 2006-09-17. Hentet 2006-09-26. av J. Lehmann, N. Kaempf, W.I. Woods, W. Sombroek, D.C. Kern, T.J.F. Cunha et al., kapitel 5, 2003.
^ «Amazonian Terra Preta» Arkiveret 27. februar 2008 hos Wayback Machine, ecoworld.com

Eksterne henvisninger

Youtube: 2023, Amazon's black earth. A miracle cure?
"Programme Summary: The Secret of El Dorado". BBC Two, 9 pm, Torsdag 19. desember 2005. Hentet 30. oktober 2012.
Bechtold,G.: "«Research work, homepage and thesis about Terra Preta with maps of TP sites and TP field work in Belterra, Pará»". Hentet 30. oktober 2012.
«Putting the carbon back: The hundred billion tonne challenge», Nature 442, 620-623 (10. august 2006), doi:10.1038/442620a
«Terra Preta Amazonian Earth», Intervju med Dr. Bruno Glaser i META magazine

[1] 2009, nature.com: The bright prospect of biochar Citat: "...According to archaeologists, the rich, black and fertile terra preta was created by adding a mixture of bone, manure and charcoal to the otherwise relatively infertile soil over many years. The charcoal – believed to be the key ingredient – is 70 times more concentrated in terra preta than in surrounding soils and is formed by heating biomass in an oxygen-poor or oxygen-free environment...."

[2] ttp://www.abc.net.au/rural/news/content/201102/s3136085.htm Dr Johannes Lehmann. notes 9000 year old terra preta soils

[3] 01 December 2020, cambridge.org: The geoglyph sites of Acre, Brazil: 10 000-year-old land-use practices and climate change in Amazonia Citat: "...Over the past 20 years, research on Amazonian Dark Earths—terra preta—has advanced our knowledge of ancient Amerindian landscape management practices, both in riverine bluffs and upland terra firme forests near Amazonia's main riverine routes (see McMichael et al. Reference McMichael, Palace, Bush, Braswell, Hagen, Neves, Silman, Tamanaha and Czarnecki2014a: fig. 1). The dark earths are anthropogenic, highly fertile soils created by centuries of soil mulching over the otherwise poor Amazonian latosols..."

[devevanwoods-4] [1] "Discovery and awareness of anthropogenic amazonian dark earths (terra preta)", by William M. Denevan, University of Wisconsin–Madison, and William I. Woods, University of Kansas.

[neves01-5] E.G. Neves, R.N. Bartone, J.B. Petersen & M.J. Heckenberger (2001). The timing of Terra Preta formation in the central Amazon: new data from three sites in the central Amazon. s. 10.{{cite book}}: CS1-vedligeholdelse: Flere navne: authors list (link)

[Erickson23-6] "Historical Ecology and Future Explorations" i Amazonian Dark Earths: origin, properties, and management "Arkivert kopi". Arkiveret fra originalen 2006-09-17. Hentet 2006-09-26. av J. Lehmann, N. Kaampf, W.I. Woods, W. Sombroek, D.C. Kern, T.J.F. Cunha et al., kapittel 23, 2003. (Clark Erickson), s. 484

[lehmann03-7] «Classification of Amazonian Dark Earths and other Ancient Anthropic Soils» i Amazonian Dark Earths: origin, properties, and management "Arkiveret kopi". Arkiveret fra originalen 2006-09-17. Hentet 2006-09-26. av J. Lehmann, N. Kaempf, W.I. Woods, W. Sombroek, D.C. Kern, T.J.F. Cunha et al., kapitel 5, 2003.

[8] «Amazonian Terra Preta» Arkiveret 27. februar 2008 hos Wayback Machine, ecoworld.com

[1]

[2]

[3]

[4]

[5]

[6]

[7]

[8]