terra preta

The origins of the Amazonian dark earths were not immediately clear to later settlers. 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 its formation to be a result of sedimentation in tertiary lakes or in recent ponds.{{Cn|date=March 2021}}

Soils with elevated charcoal content and a common presence of pottery remains can accrete accidentally near living quarters as residues from food preparation, cooking fires, animal and fish bones, broken pottery, etc., accumulated. Many terra preta soil structures are now thought to have formed under kitchen middens, as well as being manufactured intentionally on larger scales.{{Cite book|url={{google books |plainurl=y |id=2_K4CwAAQBAJ|page=59}} |title=Amazonia in the Anthropocene: People, Soils, Plants, Forests|last=Kawa|first=Nicholas C.|date=2016-05-10|publisher=University of Texas Press|isbn=9781477308448|language=en}}{{cite journal |last1=Clement |first1=Charles R. |last2=Denevan |first2=William M. |last3=Heckenberger |first3=Michael J. |last4=Junqueira |first4=André Braga |last5=Neves |first5=Eduardo G. |last6=Teixeira |first6=Wenceslau G. | last7=Woods |first7=William I. |display-authors=1 |title=The domestication of Amazonia before European conquest |journal=Proceedings of the Royal Society B: Biological Sciences |volume=282 |issue=1812 |date=2015-08-07 |issn=0962-8452 |pmid=26202998 |pmc=4528512 |doi=10.1098/rspb.2015.0813 |doi-access=free |page=20150813}}

Farmed areas around living areas are referred to as terra mulata. Terra mulata soils are more fertile than surrounding soils but less fertile than terra preta, and were most likely intentionally improved using charcoal.{{citation needed|date=October 2014}}

This type of soil appeared between 450 BCE and 950 CE at sites throughout the Amazon Basin. Recent research has reported that terra preta may be of natural origin, suggesting that pre-Columbian people intentionally utilized and improved existing areas of soil fertility scattered among areas of lower fertility.{{Cite journal|last1=Silva|first1=Lucas C. R.|last2=Corrêa|first2=Rodrigo Studart|last3=Wright|first3=Jamie L.|last4=Bomfim|first4=Barbara|last5=Hendricks|first5=Lauren|last6=Gavin|first6=Daniel G.|last7=Muniz|first7=Aleksander Westphal|last8=Martins|first8=Gilvan Coimbra|last9=Motta|first9=Antônio Carlos Vargas|last10=Barbosa|first10=Julierme Zimmer|last11=Melo|first11=Vander de Freitas|display-authors=1|date=2021-01-04|title=A new hypothesis for the origin of Amazonian Dark Earths|journal=Nature Communications|language=en|volume=12|issue=1|pages=127|doi=10.1038/s41467-020-20184-2|pmid=33397930 | pmc=7782733|bibcode=2021NatCo..12..127S |issn=2041-1723|doi-access=free}}

Amazonians formed complex, large-scale social formations, including chiefdoms (particularly in the inter-fluvial regions) and even large towns and cities.{{sfn|Mann|2005|p=296}} For instance, the culture on the island of Marajó may have developed social stratification and supported a population of 100,000. Amazonians may have used terra preta to make the land suitable for large-scale agriculture.{{sfn|Mann|2005}}

Spanish explorer Francisco de Orellana was the first European to traverse the Amazon River in the 16th century. He reported densely populated regions extending hundreds of kilometres along the river, suggesting population levels exceeding even those of today. Orellana may have exaggerated the level of development, although that is disputed. The evidence to support his claim comes from the discovery of geoglyphs dating between 0–1250 CE and from terra preta.{{cite news|url=https://www.nytimes.com/2012/01/15/world/americas/land-carvings-attest-to-amazons-lost-world.html?_r=1|title=Once Hidden by Forest, Carvings in Land Attest to Amazon's Lost World|first=Simon |last=Romero|date=14 January 2012|newspaper=The New York Times}}{{cite web|url=http://www.bbc.co.uk/programmes/b0122njp|title=Unnatural Histories - Amazon|publisher=BBC Four}} Beyond the geoglyphs, these populations left no lasting monuments, possibly because they built with wood, which would have rotted in the humid climate, as stone was unavailable.{{Cn|date=March 2021}}

Whatever its extent, this civilization vanished after the demographic collapse of the 16th and 17th century, due to European-introduced diseases such as smallpox and bandeirante slave-raiding.{{Cite journal|last=Wilkinson|first=David|date=1 April 2016|title=Amazonian Civilization?|url=https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=1986&context=ccr|journal=Comparative Civilizations Review|volume=74|pages=1–15|via=Brigham Young University's ScholarsArchive}} The settled agrarians again became nomads, while still maintaining specific traditions of their settled forebears. Their semi-nomadic descendants have the distinction among tribal indigenous societies of a hereditary, yet landless, aristocracy, a historical anomaly for a society without a sedentary, agrarian culture.{{Cn|date=March 2021}}

Moreover, many indigenous peoples adapted to a more mobile lifestyle to escape 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 cultivate the renewed soil as they migrated. Slash-and-char agriculture may have been an adaptation to these conditions. For 350 years after the European arrival, the Portuguese portion of the basin remained untended.{{Cn|date=March 2021}}

Terra preta soils are found mainly in the Brazilian Amazon, where Sombroek et al.{{Cite web|url={{google books |plainurl=y |id=glb1BwAAQBAJ|page=77}}|title=Classification of Amazonian Dark Earths and other Ancient Anthropic Soils |first1=J. |last1=Lehmann |first2=N. |last2=Kaempf |first3=W.I. |last3=Woods |first4=W. |last4=Sombroek |first5=D.C. |last5=Kern |first6=T.J.F. |last6=Cunha |pages=77–102}} in {{harvnb|Lehmann|Kern|Glaser|Woods|2007|year=2003}} estimate that they cover at least 0.1–0.3%, or {{convert|6300|to|18900|km2}} of low forested Amazonia; but others estimate this surface at 10.0% or more (twice the area of Great Britain).{{harvnb|Mann|2002}} [http://www.ecoworld.com/blog/2007/11/27/terra-preta/ extract quoted here] {{webarchive|url=https://web.archive.org/web/20080227020130/http://www.ecoworld.com/blog/2007/11/27/terra-preta/ |date=27 February 2008 }}. Recent model-based predictions suggest that the extent of terra preta soils may be of 3.2% of the forest.{{cite journal|

title=Predicting pre-Columbian anthropogenic soils in Amazonia |first1=C. H. |last1=McMichael |first2=M. W |last2=Palace |first3 =M. B.| last3=Bush |first4=B. |last4=Braswell |first5=S. |last5=Hagen |first6=E.G. |last6=Neves |first7=M. R.| last7=Silman| first8=E. K. |last8=Tamanaha| first9=C. |last9= Czarnecki |journal= Proceedings of the Royal Society B: Biological Sciences|volume=281 |issue=20132475|pages=1–9 |year=2014|doi=10.1098/rspb.2013.2475 |pmid=24403329 |pmc=3896013 }}

Terra preta exists in small plots averaging {{convert|20|ha}}, but areas of almost {{convert|360|ha}} have also been reported. They are found among various climatic, geological, and topographical situations. Their distributions either follow main water courses, from East Amazonia to the central basin,{{cite journal |url=http://www.css.cornell.edu/faculty/lehmann/publ/PlantSoil%20249,%20343-357,%202003%20Lehmann.pdf |title=Nutrient availability and leaching in an archaeological Anthrosol and a Ferralsol of the Central Amazon basin: fertilizer, manure and charcoal amendments |first1=J. |last1=Lehmann |first2=J. |last2=Pereira da Silva Jr. |first3=C. |last3=Steiner |first4=T. |last4=Nehls |first5=W. |last5=Zech |first6=Bruno |last6=Glaser |journal=Plant and Soil |volume=249 |issue=2|pages=343–357 |year=2003|doi=10.1023/A:1022833116184 |bibcode=2003PlSoi.249..343L |s2cid=2420708 }} or are located on interfluvial sites (mainly of circular or lenticular shape) and of a smaller size averaging some {{convert|1.4|ha}} (see distribution map of terra preta sites in Amazon basin).{{Cite web|url=http://www.gerhardbechtold.com/TP/BrazilTP3.php|title=Terra Preta Sites|website=www.gerhardbechtold.com|access-date=2018-08-04|first=G. |last=Bechtold}} The spreads of tropical forest between the savannas could be mainly anthropogenic—a notion with dramatic implications worldwide for agriculture and conservation.{{Cite journal|url=http://www.sas.upenn.edu/~cerickso/baures/Mann2.html|first=Charles C. |last=Mann|title=Earthmovers of the Amazon|doi=10.1126/science.321.5893.1148|pmid=18755950 |journal=Science |date=4 February 2000 |volume= 287 |issue=5893 |pages=1148–1152 |s2cid=206581907 }} Archaeological research in the Beni area, directly linked with the recent renewal of interest on terra preta, as well as photographs of experimental reconstructions of that mode of agriculture.

Terra preta sites are also known in the Llanos de Moxos of Bolivia, Ecuador, Peru and French Guiana,{{cite web|date=January 2005|url=http://www.cnes.fr/automne_modules_files/csg_pub/articles/r340_CREUSER_LHISTOIRE_Latitude_5_N67.pdf |title=Vivre en Guyane" - compte rendu succint de découverte de sites de Terra preta en Guyane. |trans-title=Living in French Guiana - summary report discovery of terra preta sites in French Guiana|first=Marie-Laure |language=fr|last=Mandin|archive-url=https://web.archive.org/web/20130723232815/http://www.cnes.fr/automne_modules_files/csg_pub/articles/r340_CREUSER_LHISTOIRE_Latitude_5_N67.pdf |archive-date=23 July 2013 |url-status=dead}}Walker, John H. (2011), "Amazonian Dark Earth and Ring Ditches in the Central Llanos de Mojos, Bolivia," Culture, Agriculture, Food and Environment, Vol 33, No 1, pp 2. and on the African continent in Benin, Liberia, and the South African savannas.

In the international soil classification system World Reference Base for Soil Resources (WRB) Terra preta is called Pretic Anthrosol. The most common original soil before transformed into a terra preta is the Ferralsol. Terra preta has a carbon content ranging from high to very high (more than 13–14% organic matter) in its A horizon, but without hydromorphic characteristics.{{Cite web|url=http://www.gerhardbechtold.com/TP/gbtp.php|title=Gerhard Bechtold: Terra Preta|last=Bechtold|first=Gerhard|website=www.gerhardbechtold.com|access-date=2018-08-05}} Terra preta presents important variants. For instance, gardens close to dwellings received more nutrients than fields farther away.{{Cite journal|last=Harder|first=Ben|date=2006-03-04|title=Smoldered-Earth Policy|journal=Science News|language=en|volume=169|issue=9|pages=133|doi=10.2307/3982299|issn=0036-8423|jstor=3982299}}

The variations in Amazonian dark earths prevent clearly determining whether all of them were intentionally created for soil improvement or whether the lightest variants are a by-product of habitation.{{Cn|date=March 2021}}

Terra preta's capacity to increase its own volume—thus to sequester more carbon—was first documented by pedologist William I. Woods of the University of Kansas. This remains the central mystery of terra preta.{{Cn|date=March 2021}}

The processes responsible for the formation of terra preta soils are:{{sfn|Glaser|2007}}

• Incorporation of wood charcoal
• Incorporation of organic matter and of nutrients
• Growth of microorganisms and animals in the soil

The transformation of biomass into charcoal produces a series of charcoal derivatives known as pyrogenic or black carbon, the composition of which varies from lightly charred organic matter, to soot particles rich in graphite formed by recomposition of free radicals.{{Cite journal|last1=Hedges|first1=J.I|last2=Eglinton|first2=G|last3=Hatcher|first3=P.G|last4=Kirchman|first4=D.L|last5=Arnosti|first5=C|last6=Derenne|first6=S|last7=Evershed|first7=R.P|last8=Kögel-Knabner|first8=I|author8-link=Ingrid Kögel-Knabner|last9=de Leeuw|first9=J.W|date=October 2000|title=The molecularly-uncharacterized component of nonliving organic matter in natural environments|journal=Organic Geochemistry|volume=31|issue=10|pages=945–958|doi=10.1016/s0146-6380(00)00096-6|bibcode=2000OrGeo..31..945H |issn=0146-6380}}Cited in {{harvnb|Glaser|2007}}. All types of carbonized materials are called charcoal. By convention, charcoal is considered to be any natural organic matter transformed thermally or by a dehydration reaction with an oxygen/carbon (O/C) ratio less than 60; smaller values have been suggested.{{Cite journal|last1=Stoffyn-Egli|first1=P.|last2=Potter|first2=T.M.|last3=Leonard|first3=J.D.|last4=Pocklington|first4=R.|date=May 1997|title=The identification of black carbon particles with the analytical scanning electron microscope: methods and initial results|journal=Science of the Total Environment|volume=198|issue=3|pages=211–223|doi=10.1016/s0048-9697(97)05464-8|issn=0048-9697|bibcode=1997ScTEn.198..211S}} Cited in {{harvnb|Glaser|2007}}. Because of possible interactions with minerals and organic matter from the soil, it is almost impossible to identify charcoal by determining only the proportion of O/C. The hydrogen/carbon percentage{{Cite journal|last1=Kim|first1=Sunghwan|last2=Kaplan|first2=Louis A.|last3=Benner|first3=Ronald|last4=Hatcher|first4=Patrick G.|date=December 2004|title=Hydrogen-deficient molecules in natural riverine water samples—evidence for the existence of black carbon in DOM|journal=Marine Chemistry|volume=92|issue=1–4|pages=225–234|doi=10.1016/j.marchem.2004.06.042|bibcode=2004MarCh..92..225K |issn=0304-4203}} Cited in {{harvnb|Glaser|2007}}. or molecular markers such as benzenepolycarboxylic acid,{{Cite journal|last1=Glaser|first1=B|last2=Haumaier|first2=L|last3=Guggenberger|first3=G|last4=Zech|first4=W|date=January 1998|title=Black carbon in soils: the use of benzenecarboxylic acids as specific markers|journal=Organic Geochemistry|volume=29|issue=4|pages=811–819|doi=10.1016/s0146-6380(98)00194-6|bibcode=1998OrGeo..29..811G|issn=0146-6380}} Cited in {{harvnb|Glaser|2007}} are used as a second level of identification.{{sfn|Glaser|2007}}

Indigenous people added low temperature charcoal to poor soils. Up to 9% black carbon has been measured in some terra preta (against 0.5% in surrounding soils).{{Cite journal|last1=Woods|first1=William I.|last2=McCann|first2=Joseph M.|date=1999|title=The Anthropogenic Origin and Persistence of Amazonian Dark Earths|journal=Yearbook. Conference of Latin Americanist Geographers|volume=25|pages=7–14|jstor=25765871}} Cited in {{harvnb|Marris|2006}} Other measurements found carbon levels 70 times greater than in surrounding ferralsols,{{sfn|Glaser|2007}} with approximate average values of 50 Mg/ha/m.{{Cite journal|last1=Glaser|first1=Bruno|last2=Haumaier|first2=Ludwig|last3=Guggenberger|first3=Georg|last4=Zech|first4=Wolfgang|date=January 2001|title=The 'Terra Preta' phenomenon: a model for sustainable agriculture in the humid tropics|journal=Naturwissenschaften|language=en|volume=88|issue=1|pages=37–41|doi=10.1007/s001140000193|pmid=11302125|issn=0028-1042|bibcode=2001NW.....88...37G|s2cid=26608101}} Cited in {{Cite journal|last1=MAJOR|first1=JULIE|last2=STEINER|first2=CHRISTOPH|last3=DITOMMASO|first3=ANTONIO|last4=FALCAO|first4=NEWTON P.S.|last5=LEHMANN|first5=JOHANNES|date=June 2005|title=Weed composition and cover after three years of soil fertility management in the central Brazilian Amazon: Compost, fertilizer, manure and charcoal applications|journal=Weed Biology and Management|language=en|volume=5|issue=2|pages=69–76|doi=10.1111/j.1445-6664.2005.00159.x|issn=1444-6162}}

The chemical structure of charcoal in terra preta soils is characterized by poly-condensed aromatic groups that provide prolonged biological and chemical stability against microbial degradation; it also provides, after partial oxidation, the highest nutrient retention.{{sfn|Glaser|2007}} Low temperature charcoal (but not that from grasses or high cellulose materials) has an internal layer of biological petroleum condensates that the bacteria consume, and is similar to cellulose in its effects on microbial growth.{{cite conference|title=Plant nitrogen uptake doubled in charcoal amended soils|first=Christoph |last=Steiner |conference=Energy with Agricultural Carbon Utilization Symposium, 2004}} Charring at high temperature consumes that layer and brings little increase in soil fertility. The formation of condensed aromatic structures depends on the method of manufacture of charcoal.

{{cite web|title=Organic chemistry studies on Amazonian Dark Earths |first1=G. |last1=Guggenberger|first2= W. |last2=Zech |url={{google books |plainurl=y |id=glb1BwAAQBAJ}}}} in {{harvnb|Lehmann|Kern|Glaser|Woods|2007|year=2003}}{{Cite journal|last1=Brodowski|first1=S.|last2=Rodionov|first2=A.|last3=Haumaier|first3=L.|last4=Glaser|first4=B.|last5=Amelung|first5=W.|date=September 2005|title=Revised black carbon assessment using benzene polycarboxylic acids|journal=Organic Geochemistry|volume=36|issue=9|pages=1299–1310|doi=10.1016/j.orggeochem.2005.03.011|bibcode=2005OrGeo..36.1299B |issn=0146-6380}} The slow oxidation of charcoal creates carboxylic groups; these increase the cation exchange capacity of the soil.{{Cite conference |last1=Glaser |first1=Bruno |last2=Haumaier |first2=Ludwig |last3=Guggenberger |first3=Georg |last4=Zech |first4=Wolfgang |date=2018-08-04 |title=Stability of soil organic matter in Terra Preta soils |trans-title=Stabilité de la matière organique dans les sols de Terra Preta |url=https://www.researchgate.net/publication/255614178 |conference=16th World Congress of Soil Science 1998 |location=France |via=ResearchGate}}{{Cite book|chapter-url={{google books |plainurl=y |id=6fbwAAAAMAAJ}}|title=Humic substances in soil and crop sciences: selected readings : proceedings of a symposium cosponsored by the International Humic Substances Society ... Chicago, Illinois, 2 December 1985|editor-last=MacCarthy|editor-first=Patrick|date=1990|isbn=9780891181040|language=en|chapter=Ecological aspects of soil organic matter in tropical land use |first1=W. |last1=Zech|first2=L. |last2=Haumaier |first3=R. |last3=Hempfling|pages= 187–202|publisher= American Society of Agronomy and Soil Science Society of America}} Cited in {{harvnb|Glaser|2007}}. The nucleus of black carbon particles produced by the biomass remains aromatic even after thousands of years and presents the spectral characteristics of fresh charcoal. Around that nucleus and on the surface of the black carbon particles are higher proportions of forms of carboxylic and phenolic carbons spatially and structurally distinct from the particle's nucleus. Analysis of the groups of molecules provides evidences both for the oxidation of the black carbon particle itself, as well as for the adsorption of non-black carbon.{{Cite journal|last1=Lehmann|first1=Johannes|last2=Liang|first2=Biqing|last3=Solomon|first3=Dawit|last4=Lerotic|first4=Mirna|last5=Luizão|first5=Flavio|last6=Kinyangi|first6=James|last7=Schäfer|first7=Thorsten|last8=Wirick|first8=Sue|last9=Jacobsen|first9=Chris|date=2005-02-16|title=Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy for mapping nano-scale distribution of organic carbon forms in soil: Application to black carbon particles|journal=Global Biogeochemical Cycles|language=en|volume=19|issue=1|pages=GB1013|doi=10.1029/2004gb002435|issn=0886-6236|bibcode=2005GBioC..19.1013L|doi-access=free}}

This charcoal is thus decisive for the sustainability of terra preta.{{Cite conference |last1=Lehmann |first1=Johannes |last2=Silva |first2=José Junior |last3=Rondon |first3=Marco |last4=Manoel Da Silva |first4=Cravo |last5=Greenwood |first5=Jaqueline |last6=Nehls |first6=Thomas |last7=Steiner |first7=Christoph |last8=Glaser |first8=Bruno |date=14-21 August 2002 |title=Slash and Char: a feasible alternative for soil fertility management in the Central Amazon? |url=https://www.researchgate.net/publication/200736459 |conference=17th World Congress of Soil Science 2002 |location=Thailand |via=ResearchGate}} Amending ferralsol with wood charcoal greatly increases productivity. Globally, agricultural lands have lost on average 50% of their carbon due to intensive cultivation and other damage of human origin.

Fresh charcoal must be "charged" before it can function as a biotope.{{Cite web|url=http://www.holon.se/folke/|title=Folke Günther on ecological design,thermodynamics of living systems,ecological engineering, nutrient recycling and oil depletion|last=Günther|first=Folke|website=www.holon.se|access-date=2018-08-05}} Several experiments demonstrate that uncharged charcoal can bring a temporary depletion of available nutrients when first put into the soil, that is until its pores fill with nutrients. This is overcome by soaking the charcoal for two to four weeks in any liquid nutrient (urine, plant tea, worm tea, etc.).{{cite book|first=Kelpie | last=Wilson| title=The Biochar Cookbook: Practical Guidelines and Recipes for Making and Using Biochar – Volume I|date=2020-02-01|pages=14–19}}

Charcoal's porosity brings better retention of organic matter, of water and of dissolved nutrients,{{Cite journal|last1=Pietikainen|first1=Janna|last2=Kiikkila|first2=Oili|last3=Fritze|first3=Hannu|date=May 2000|title=Charcoal as a habitat for microbes and its effect on the microbial community of the underlying humus|journal=Oikos|language=en|volume=89|issue=2|pages=231–242|doi=10.1034/j.1600-0706.2000.890203.x|bibcode=2000Oikos..89..231P |issn=0030-1299}} Cited in {{harvnb|Glaser|2007}}. as well as of pollutants such as pesticides and aromatic poly-cyclic hydrocarbons.{{cite journal|url=http://www.ejbiotechnology.info/index.php/ejbiotechnology/article/view/v5n2-1 |title=Biodegradation of two commercial herbicides (Gramoxone and Matancha) by the bacteria Pseudomonas putida |doi=10.2225/vol5-issue2-fulltext-1 |first1=M. |last1=Kopytko |first2=G. |last2=Chalela |first3=F. |last3=Zauscher |year=2002 |journal=Electronic Journal of Biotechnology |volume=5 |issue=2 |pages=182–195|doi-access=free |hdl=1807/1165 |hdl-access=free }} Cited in {{harvnb|Glaser|2007}}.

Charcoal's high absorption potential of organic molecules (and of water) is due to its porous structure.{{sfn|Glaser|2007}} Terra preta's high concentration of charcoal supports a high concentration of organic matter (on average three times more than in the surrounding poor soils),{{sfn|Glaser|2007}}{{harnvb|Sombroek|1966|p=283}} Cited in {{harvnb|Glaser|2007}}. up to 150 g/kg. Organic matter can be found at {{convert|1|to|2|m}} deep.

Bechtold proposes to use terra preta for soils that show, at {{convert|50|cm|in|sp=us}} depth, a minimum proportion of organic matter over 2.0–2.5%. The accumulation of organic matter in moist tropical soils is a paradox, because of optimum conditions for organic matter degradation. It is remarkable that anthrosols regenerate in spite of these tropical conditions' prevalence and their fast mineralisation rates. The stability of organic matter is mainly because the biomass is only partially consumed.

Terra preta soils also show higher quantities of nutrients, and a better retention of these nutrients, than surrounding infertile soils. The proportion of P reaches 200–400 mg/kg.Lehmann, Johannes.som

"[http://www.css.cornell.edu/faculty/lehmann/terra_preta/TerraPretahome.htm Site Terra Preta de Índio - Soil Biogeochemistry]", Cornell University. The quantity of N is also higher in anthrosol, but that nutrient is immobilized because of the high proportion of C over N in the soil.

Anthrosol's availability of P, Ca, Mn and Zn is higher than ferrasol. The absorption of P, K, Ca, Zn, and Cu by the plants increases when the quantity of available charcoal increases. The production of biomass for two crops (rice and Vigna unguiculata) increased by 38–45% without fertilization (P < 0.05), compared to crops on fertilized ferralsol.

Amending with charcoal pieces approximately {{convert|20|mm|in|sp=us}} in diameter, instead of ground charcoal, did not change the results except for manganese (Mn), for which absorption considerably increased.

Nutrient leaching is minimal in this anthrosol, despite their abundance, resulting in high fertility. When inorganic nutrients are applied to the soil, however, the nutrients' drainage in anthrosol exceeds that in fertilized ferralsol.

As potential sources of nutrients, only C (via photosynthesis) and N (from biological fixation) can be produced in situ. All the other elements (P, K, Ca, Mg, etc.) must be present in the soil. In Amazonia, the provisioning of nutrients from the decomposition of naturally available organic matter fails as the heavy rainfalls wash away the released nutrients and the natural soils (ferralsols, acrisols, lixisols, arenosols, uxisols, etc.) lack the mineral matter to provide those nutrients. The clay matter that exists in those soils is capable of holding only a small fraction of the nutrients made available from decomposition. In the case of terra preta, the only possible nutrient sources are primary and secondary. The following components have been found:

• Human and animal excrements (rich in P and N);
• Kitchen refuse, such as animal bones and tortoise shells (rich in P and Ca);
• Ash residue from incomplete combustion (rich in Ca, Mg, K, P and charcoal);
• Biomass of terrestrial plants (e.g. compost); and
• Biomass of aquatic plants (e.g. algae).

Saturation in pH and in base is more important than in the surrounding soils.

{{harvnb|Sombroek|1966}}; Smith, 1980; Kern and Kämpf, 1989; {{harvnb|Sombroek|Nachtergaele|Hebel|1993}}; {{harvnb|Glaser|Balashov|Haumaier|Guggenberger|2007}}; {{harvnb|Lehmann|Kern|Glaser|Woods|2007}}; {{harvnb|Liang|Lehmann|Solomon|Kinyangi|2006}}

The peregrine earthworm Pontoscolex corethrurus (Oligochaeta: Glossoscolecidae) ingests charcoal and mixes it into a finely ground form with the mineral soil. P. corethrurus is widespread in Amazonia and notably in clearings after burning processes thanks to its tolerance of a low content of organic matter in the soil.

{{cite journal |author=Jean-François Ponge |author2=Stéphanie Topoliantz |author3=Sylvain Ballof |author4=Jean-Pierre Rossi |author5=Patrick Lavelle |author6=Jean-Marie Betsch |author7=Philippe Gaucher |year=2006 |title=Ingestion of charcoal by the Amazonian earthworm Pontoscolex corethrurus: a potential for tropical soil fertility |journal=Soil Biology and Biochemistry |volume=38 |issue=7 |pages=2008–2009 |doi=10.1016/j.soilbio.2005.12.024 |bibcode=2006SBiBi..38.2008P |url=https://www.researchgate.net/publication/44735820 |format=PDF}} This as an essential element in the generation of terra preta, associated with agronomic knowledge involving layering the charcoal in thin regular layers favorable to its burying by P. corethrurus.{{Cn|date=March 2021}}

Some ants are repelled from fresh terra preta; their density is found to be low about 10 days after production compared to that in control soils.{{cite web|first=N. Sai Bhaskar |last=Reddy |url=http://e-terrapretarooftopexp.blogspot.com |title=Terra Preta Roof-Top Experiments}}

A newly coined term is 'synthetic terra preta'.Chia, C., Munroe, P., Joseph, S. and Lin, Y. 2010. Microscopic characterisation of synthetic Terra Preta. Soil Research, 48 (7), pp. 593—605{{Cite web|url=http://www.css.cornell.edu/faculty/lehmann/research/terra%20preta/terrapretamain.html|title=Terra Preta de Indio | first=Johannes |last=Lehmann | website=www.css.cornell.edu | access-date=7 August 2018}} STP is a fertilizer consisting of materials thought to replicate the original materials, including crushed clay, blood and bone meal, manure and biochar is of particulate nature and capable of moving down the soil profile and improving soil fertility and carbon in the current soil peds and aggregates over a viable time frame.{{citation |last=Adams |first=M. |year=2013 |title=Securing soil through carbon. |location=Sydney |publisher=University of Sydney}} Such a mixture provides multiple soil improvements reaching at least the quality of terra mulata. Blood, bone meal and chicken manure are useful for short term organic manure addition.{{Cite journal|last=Rahman|first=M. Mizanur|date=2013-05-15|title=Nutrient-Use and Carbon-Sequestration Efficiencies in Soils from Different Organic Wastes in Rice and Tomato Cultivation|journal=Communications in Soil Science and Plant Analysis|language=en|volume=44|issue=9|pages=1457–1471|doi=10.1080/00103624.2012.760575|bibcode=2013CSSPA..44.1457R |s2cid=96404482|issn=0010-3624}} Perhaps the most important and unique part of the improvement of soil fertility is carbon, thought to have been gradually incorporated 4 to 10 thousand years ago.{{Cite journal|last1=Cunha|first1=Tony Jarbas Ferreira|last2=Madari|first2=Beata Emoke|last3=Canellas|first3=Luciano Pasqualoto|last4=Ribeiro|first4=Lucedino Paixão|last5=Benites|first5=Vinicius de Melo|last6=Santos|first6=Gabriel de Araújo|date=February 2009|title=Soil organic matter and fertility of anthropogenic dark earths (Terra Preta de Índio) in the Brazilian Amazon basin|journal=Revista Brasileira de Ciência do Solo|volume=33|issue=1|pages=85–93|doi=10.1590/S0100-06832009000100009|issn=0100-0683|doi-access=free}} Biochar is capable of decreasing soil acidity and if soaked in nutrient rich liquid can slowly release nutrients and provide habitat for microbes in soil due to its high porosity surface area.

The goal is an economically viable process that could be included in modern agriculture. Average poor tropical soils are easily enrichable to terra preta nova by the addition of charcoal and condensed smoke.{{cite web |url= http://ngm.nationalgeographic.com/2008/09/soil/mann-text |title=Our Good Earth |first=Charles C. |last=Mann|work=National Geographic Magazine |date=September 2008 |archiveurl=https://web.archive.org/web/20080819113653/http://ngm.nationalgeographic.com/2008/09/soil/mann-text |archivedate=2008-08-19}} Terra preta may be an important avenue of future carbon sequestration while reversing the current worldwide decline in soil fertility and associated desertification. Whether this is possible on a larger scale has yet to be proven. Tree Lucerne (tagasaste or Cytisus proliferus) is one type of fertilizer tree used to make terra preta. Efforts to recreate these soils are underway by companies such as Embrapa and other organizations in Brazil.{{cite web|url=http://www.cpaa.embrapa.br/|title=Embrapa Amazônia Ocidental - Portal Embrapa|website=www.cpaa.embrapa.br|access-date=14 February 2018|archive-date=29 May 2014|archive-url=https://web.archive.org/web/20140529092833/http://www.cpaa.embrapa.br/|url-status=dead}}

Synthetic terra preta is produced at the Sachamama Center for Biocultural Regeneration in High Amazon, Peru. This area has many terra preta soil zones, demonstrating that this anthrosol was created not only in the Amazon basin, but also at higher elevations.{{Cite web |url=http://www.casasangapilla.com/sachamamain/ |title=Sachamama |access-date=20 January 2016 |archive-url=https://web.archive.org/web/20160125055032/http://www.casasangapilla.com/sachamamain/ |archive-date=25 January 2016 |url-status=dead}}

A synthetic terra preta process was developed by Alfons-Eduard Krieger to produce a high humus, nutrient-rich, water-adsorbing soil.{{cite web|url=https://patents.google.com/patent/EP2188230B1/sv|title=Verfahren zur herstellung von humus- und nährstoffreichen sowie wasserspeichernden böden oder bodensubstraten für nachhaltige landnutzungs- und siedlungssysteme}}

Terra preta sanitation (TPS) systems have been studied as an alternative sanitation option by using the effects of lactic-aid conditions in urine-diverting dry toilets and a subsequent treatment by vermicomposting.{{Cite journal |last1=Otterpohl |first1=R. |last2=Reckin |first2=J. |last3=Pieplow |first3=H. |last4=Buzie |first4=C. |last5=Bettendorf |first5=T. |last6=Factura |first6=H. |date=2010 |title=Terra Preta sanitation: re-discovered from an ancient Amazonian civilisation – integrating sanitation, bio-waste management and agriculture |url=http://www.sswm.info/library/696 |journal=Water Science and Technology |volume=61 |issue=10 |pages=2673–2679 |doi=10.2166/wst.2010.201|pmid=20453341 |doi-access= |bibcode=2010WSTec..61.2673F }}

• {{Annotated link |1491: New Revelations of the Americas Before Columbus|1491: New Revelations of the Americas Before Columbus}}
• {{Annotated link |Agroforestry}}
• {{Annotated link |Belterra, Pará}}
• {{Annotated link |Forest islands}}
• {{Annotated link |Pre-Columbian agriculture in the Amazon Basin}}
• {{Annotated link |Texas Blackland Prairies}}

{{Reflist|refs=

{{cite journal|last1=Mao|first1=J.-D.|last2=Johnson|first2=R. L.|last3=Lehmann|first3=J.|last4=Olk|first4=J.|last5=Neeves|first5=E. G.|last6=Thompson|first6=M. L.|last7=Schmidt-Rohr|first7=K.|year=2012|title=Abundant and stable char residues in soils: implications for soil fertility and carbon sequestration|journal=Environmental Science and Technology|volume=46|issue=17|pages= 9571–9576 |doi=10.1021/es301107c|pmid=22834642|quote=Terra Preta soils consist predominantly of char residues composed of ~6 fused aromatic rings|language=EN|citeseerx=10.1.1.698.270|bibcode=2012EnST...46.9571M}}

}}

{{Refbegin}}

• {{Cite book|url={{google books |plainurl=y |id=glb1BwAAQBAJ|page=77}}|title=Amazonian Dark Earths: Origin Properties Management|editor-last1=Lehmann|editor-first1=Johannes|editor-last2=Kern|editor-first2=Dirse C. |editor3-last=Glaser|editor3-first=Bruno|editor4-last=Woods|editor4-first=William I.|date=8 May 2007|publisher=Springer Science & Business Media|isbn=9781402025976|language=en}}
• {{cite web |first=Manuel |last=Arroyo-Kalin |url=http://www.arch.cam.ac.uk/~maa27/ |title=Geoarchaeological approaches to the study of Terras Pretas |access-date=10 July 2008 |archive-url=https://web.archive.org/web/20081030011736/http://www.arch.cam.ac.uk/~maa27/ |archive-date=30 October 2008 |url-status=dead}}
• {{cite web | title= Research work, homepage and thesis about Terra Preta with maps of TP sites and TP field work in Belterra, Pará | url=https://www.gerhardbechtold.com/TP/gbtp.html |last=Bechtold |first=G.}}
• {{cite web |url=http://www.sciam.com/article.cfm?id=pyrolyisis-terra-preta-could-eliminate-garbage-generate-oil-carbon-sequestration |title= Special Report: Inspired by Ancient Amazonians, a Plan to Convert Trash into Environmental Treasure|first=Anne |last=Casselman |date= May 2007 |work=Scientific American }}
• {{Cite journal|last1=Glaser|first1=Bruno|last2=Balashov|first2=Eugene|last3=Haumaier|first3=Ludwig|last4=Guggenberger |first4=Georg|last5=Zech|first5=Wolfgang|date=July 2007|title=Black carbon in density frations of anthropogenic soils of the Brazilian Amazon region|journal=Organic Geochemistry|volume=31|issue=7–8|pages=669–678|doi=10.1016/s0146-6380(00)00044-9|issn=0146-6380}}
• {{cite journal | last = Glaser | first = Bruno | date = 27 February 2007 | title = Prehistorically modified soils of central Amazonia: a model for sustainable agriculture in the twenty-first century | journal = Philosophical Transactions of the Royal Society B | volume = 362 | issue = 1478 | pages = 187–196 | doi = 10.1098/rstb.2006.1978 | pmid = 17255028 | pmc = 2311424 }}
• {{cite web |first=David |last=Haywood |url=http://www.publicaddress.net/default,4153.sm |title=Could the Mysterious Agricultural Techniques of an Ancient Amazonian Civilization Make New Zealand Farming More Competitive? |publisher=Public Address Radio |date=5 May 2007}}
• {{Cite journal|last1=Liang|first1=Biqing|last2=Lehmann|first2=Johannes|last3=Solomon|first3=Dawit|first4=J|last4=Kinyangi|last5=Grossman|first5=Julie|last6=B|first6=O’Neill|last7=JO|first7=Skjemstad|last8=Thies|first8=Janice|last9=FJ|first9=Luizão|date=1 September 2006|title=Black Carbon Increases Cation Exchange Capacity in Soils|url=https://www.researchgate.net/publication/200736465|journal=Soil Science Society of America Journal|volume=70|issue=5|pages=1719–1730|doi=10.2136/sssaj2005.0383|bibcode=2006SSASJ..70.1719L}}
• {{cite book|url={{google books |plainurl=y |id=KPKMDQAAQBAJ}}|title=1491: New Revelations of the Americas Before Columbus|last=Mann |first=C. C.|publisher=University of Texas|year=2005|isbn=978-1-4000-3205-1}}
• {{Cite news|url=https://www.theatlantic.com/doc/200203/mann|title=1491|last=Mann|first=Charles C.|date=2002-03-01|work=The Atlantic|access-date=2018-08-05|language=en-US}}
• {{Cite journal|last=Marris|first=Emma|date=August 2006|title=Black is the new green|journal=Nature|language=En|volume=442|issue=7103|pages=624–626|doi=10.1038/442624a|pmid=16900176|issn=0028-0836|bibcode=2006Natur.442..624M|s2cid=30544497|doi-access=free}}
• {{Cite journal|last1=Sombroek|first1=Wim G.|last2=Nachtergaele|first2=Freddy O. |last3=Hebel|first3=Axel|year=1993|title=Amounts, Dynamics and Sequestering of Carbon in Tropical and Subtropical Soils|journal=Ambio|volume=22|issue=7|pages=417–426|jstor=4314120}}
• {{Cite thesis|last=Sombroek|first=W.G.|date=1966|title=Amazon soils : a reconnaissance of the soils of the Brazilian Amazon region|url=http://library.wur.nl/WebQuery/wurpubs/421842|volume=672|page=283|publisher=Pudoc|type=phd}}

{{Refend}}

{{Commons category|Terra preta}}

• {{Cite web|url=http://www.bbc.co.uk/science/horizon/2002/eldorado.shtml|title=The Secret of El Dorado|website=www.bbc.co.uk|access-date=2018-08-05|publisher=BBC}}
• {{cite web|title=Terra Preta |work=Hypography discussion forum |url=http://hypography.com/forums/terra-preta.html |access-date=8 May 2006 |url-status=dead |archive-url=https://web.archive.org/web/20080408165459/http://hypography.com/forums/terra-preta.html |archive-date=8 April 2008 }}
• {{cite web | title= Terra Preta Home Page | url= http://www.biochar.org | access-date=20 April 2007}}
• {{Cite web|url=http://terrapreta.bioenergylists.org|title=BioEnergy Lists: Biochar Mailing Lists {{!}} Sharing technical and event information about Biochar from the Biochar email lists|website=terrapreta.bioenergylists.org|language=en|access-date=2018-08-05}}
• {{Cite journal|last=Schiermeier|first=Quirin|date=August 2006|title=The hundred billion tonne challenge|journal=Nature|language=En|volume=442|issue=7103|pages=620–623|doi=10.1038/442620a|pmid=16900175|s2cid=26649615|issn=0028-0836|doi-access=free}}
• {{cite web | first=Anna | last=Salleh | title= Charred farm waste could gobble up carbon | date=28 June 2007 | publisher=Australian Broadcasting Corporation | url=http://www.abc.net.au/science/articles/2007/06/08/1946410.htm | work=News in Science}} ABC Science Online.
• {{cite news | first=Mark | last=Horstman | title=Agrichar – A solution to global warming? | date=23 September 2007 | publisher=Australian Broadcasting Corporation | url =http://www.abc.net.au/catalyst/stories/s2012892.htm | work =ABC TV Science: Catalyst}}

{{Soil type}}

{{Deforestation and desertification}}

{{Authority control}}

{{DEFAULTSORT:Terra Preta}}

Category:Amazon basin

Category:Types of soil

Category:Indigenous topics of the Amazon

Category:Pre-Columbian indigenous peoples of the Amazon