Terra preta

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Terra preta (Portuguese pronunciation:

Amazon Basin. 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 ("black soil of the Indian", "Indians' black earth"). Terra mulata ("mulatto earth") is lighter or brownish in color.[1]

Homemade terra preta, with charcoal pieces indicated by white arrows

Terra preta owes its characteristic black color to its weathered

Amazonian soil management and slash-and-char agriculture,[3] the charcoal is stable and remains in the soil for thousands of years, binding and retaining minerals and nutrients.[4][5]

Terra preta is characterized by the presence of low-temperature charcoal residues in high concentrations;

tiny pottery shards; of organic matter such as plant residues, animal feces, fish and animal bones, and other material; and of nutrients such as nitrogen, phosphorus, calcium, zinc and manganese.[6] Fertile soils such as terra preta show high levels of microorganic activities and other specific characteristics within particular ecosystems
.

Terra preta zones are generally surrounded by terra comum (

arenosols.[7] Deforested arable soils in the Amazon are productive for a short period of time before their nutrients are consumed or leached away by rain or flooding. This forces farmers to migrate to an unburned area and clear it (by fire).[8][9] Terra preta is less prone to nutrient leaching
because of its high concentration of charcoal, microbial life and organic matter. The combination accumulates nutrients, minerals and microorganisms and withstands leaching.

Terra preta soils were created by farming communities between 450 BCE and 950 CE.[10][11][12] Soil depths can reach 2 meters (6.6 ft). It is reported to regenerate itself at the rate of 1 centimeter (0.4 in) per year.[13]

History

Early theories

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.[citation needed]

Anthropogenic roots

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.[14][15] 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]

This type of soil appeared between 450 BCE and 950 CE at sites throughout the

Amazon Basin.[12] 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.[16]

Amazonia

Amazonians formed complex, large-scale social formations, including chiefdoms (particularly in the inter-fluvial regions) and even large towns and cities.[17] 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.[18]

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.[19][20] 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.[citation needed
]

Whatever its extent, this civilization vanished after the

demographic collapse of the 16th and 17th century, due to European-introduced diseases such as smallpox[20] and bandeirante slave-raiding.[21] 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.[citation needed
]

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.[citation needed
]

Location

Terra preta soils are found mainly in the

Brazilian Amazon, where Sombroek et al.[22] estimate that they cover at least 0.1–0.3%, or 6,300 to 18,900 square kilometres (2,400 to 7,300 sq mi) of low forested Amazonia;[1] but others estimate this surface at 10.0% or more (twice the area of Great Britain).[13][23] Recent model-based predictions suggest that the extent of terra preta soils may be of 3.2% of the forest.[24]

Terra preta exists in small plots averaging 20 hectares (49 acres), but areas of almost 360 hectares (890 acres) have also been reported. They are found among various climatic,

Terra preta sites are also known in the Llanos de Moxos of Bolivia, Ecuador, Peru and French Guiana,[28][29] and on the African continent in Benin, Liberia, and the South African savannas.[6]

Pedology

In the international soil classification system

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.[30] Terra preta presents important variants. For instance, gardens close to dwellings received more nutrients than fields farther away.[31] 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.[citation needed
]

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.[13] This remains the central mystery of terra preta.[citation needed
]

The processes responsible for the formation of terra preta soils are:[7]

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

Wood charcoal

The transformation of biomass into charcoal produces a series of charcoal derivatives known as

free radicals.[32][33] 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;[32] smaller values have been suggested.[34] 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[35] or molecular markers such as benzenepolycarboxylic acid,[36] are used as a second level of identification.[7]

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).[37] Other measurements found carbon levels 70 times greater than in surrounding ferralsols,[7] with approximate average values of 50 Mg/ha/m.[38]

The chemical structure of charcoal in terra preta soils is characterized by poly-condensed

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.[44]

This charcoal is thus decisive for the

ferralsol with wood charcoal greatly increases productivity.[25] Globally, agricultural lands have lost on average 50% of their carbon due to intensive cultivation and other damage of human origin.[13]

Fresh charcoal must be "charged" before it can function as a biotope.[46] 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.).[47]

Organic matter and nutrients

Charcoal's porosity brings better retention of organic matter, of water and of dissolved nutrients,[42][48] as well as of pollutants such as pesticides and aromatic poly-cyclic hydrocarbons.[49]

Organic matter

Charcoal's high absorption potential of organic molecules (and of water) is due to its porous structure.[7] 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),[7][38][43][50] up to 150 g/kg.[25] Organic matter can be found at 1 to 2 metres (3 ft 3 in to 6 ft 7 in) deep.[30]

Bechtold proposes to use terra preta for soils that show, at 50 centimeters (20 in) 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.[38] It is remarkable that anthrosols regenerate in spite of these tropical conditions' prevalence and their fast mineralisation rates.[25] The stability of organic matter is mainly because the biomass is only partially consumed.[38]

Nutrients

Terra preta soils also show higher quantities of nutrients, and a better retention of these nutrients, than surrounding infertile soils.[38] The proportion of P reaches 200–400 mg/kg.[51] 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.[25]

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.[25]

Amending with charcoal pieces approximately 20 millimeters (0.79 in) in diameter, instead of ground charcoal, did not change the results except for manganese (Mn), for which absorption considerably increased.[25]

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.[25]

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:[38]

Saturation in pH and in base is more important than in the surrounding soils.[51][52]

Microorganisms and animals

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.[53] 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.[citation needed]

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.[54]

Modern research on creating terra preta

Synthetic terra preta

A newly coined term is 'synthetic terra preta'.

microbes in soil due to its high porosity surface area.[2]

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.

Embrapa and other organizations in Brazil.[61]

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.[62]

A synthetic terra preta process was developed by Alfons-Eduard Krieger to produce a high humus, nutrient-rich, water-adsorbing soil.[63]

Terra preta sanitation

Terra preta sanitation (TPS) systems have been studied as an alternative

vermicomposting.[64]

See also

Notes

  1. ^ a b c Denevan, William M.; Woods, William I. "Discovery and awareness of anthropogenic amazonian dark earths (terra preta)" (PDF). Archived from the original (PDF) on 24 September 2015.
  2. ^
    PMID 22834642
    . Terra Preta soils consist predominantly of char residues composed of ~6 fused aromatic rings
  3. .
  4. .
  5. ^ Cornell University (1 March 2006). "Amazonian Terra Preta Can Transform Poor Soil into Fertile". Science Daily. Rockville, MD.
  6. ^ a b c Glaser, Bruno. "Terra Preta Web Site". Archived from the original on 25 October 2005.
  7. ^ a b c d e f g Glaser 2007.
  8. ^ Watkins and Griffiths, J. (2000). Forest Destruction and Sustainable Agriculture in the Brazilian Amazon: a Literature Review (Doctoral dissertation, The University of Reading, 2000). Dissertation Abstracts International, 15–17
  9. .
  10. ^ Neves et al. 2001, p. 10.
  11. ^ Neves, E.G.; Bartone, R.N.; Petersen, J.B.; Heckenberger, M.J. (2001). The timing of Terra Preta formation in the central Amazon: new data from three sites in the central Amazon. p. 10.
  12. ^ a b Lehmann, J.; Kaampf, N.; Woods, W.I.; Sombroek, W.; Kern, D.C.; Cunha, T.J.F. "Historical Ecology and Future Explorations". p. 484. in Lehmann et al. 2007
  13. ^ a b c d e Day, Danny (2004). "Carbon negative energy to reverse global warming". Eprida. Archived from the original on 13 September 2021. Retrieved 8 December 2007.
  14. .
  15. .
  16. .
  17. ^ Mann 2005, p. 296.
  18. ^ Mann 2005.
  19. ^ Romero, Simon (14 January 2012). "Once Hidden by Forest, Carvings in Land Attest to Amazon's Lost World". The New York Times.
  20. ^ a b "Unnatural Histories - Amazon". BBC Four.
  21. ^ Wilkinson, David (1 April 2016). "Amazonian Civilization?". Comparative Civilizations Review. 74: 1–15 – via Brigham Young University's ScholarsArchive.
  22. ^ Lehmann, J.; Kaempf, N.; Woods, W.I.; Sombroek, W.; Kern, D.C.; Cunha, T.J.F. "Classification of Amazonian Dark Earths and other Ancient Anthropic Soils". pp. 77–102. in Lehmann et al. 2007
  23. ^ Mann 2002 extract quoted here Archived 27 February 2008 at the Wayback Machine.
  24. PMID 24403329
    .
  25. ^ .
  26. ^ Bechtold, G. "Terra Preta Sites". www.gerhardbechtold.com. Retrieved 4 August 2018.
  27. 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.
  28. ^ Mandin, Marie-Laure (January 2005). "Vivre en Guyane" - compte rendu succint de découverte de sites de Terra preta en Guyane" [Living in French Guiana - summary report discovery of terra preta sites in French Guiana] (PDF) (in French). Archived from the original (PDF) on 23 July 2013.
  29. ^ 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.
  30. ^ a b Bechtold, Gerhard. "Gerhard Bechtold: Terra Preta". www.gerhardbechtold.com. Retrieved 5 August 2018.
  31. JSTOR 3982299
    .
  32. ^ .
  33. ^ Cited in Glaser 2007.
  34. ISSN 0048-9697. Cited in Glaser 2007
    .
  35. .
  36. ^
  37. ^ .
  38. ^ Steiner, Christoph. Plant nitrogen uptake doubled in charcoal amended soils. Energy with Agricultural Carbon Utilization Symposium, 2004.
  39. ^ Guggenberger, G.; Zech, W. "Organic chemistry studies on Amazonian Dark Earths". in Lehmann et al. 2007
  40. ISSN 0146-6380
    .
  41. ^ a b c Glaser, Bruno; Haumaier, Ludwig; Guggenberger, Georg; Zech, Wolfgang (4 August 2018). "Stability of soil organic matter in Terra Preta soils Stabilité de la matière organique dans les sols de Terra Preta". Institut de Sciences des Sols, University of Bayreuth. {{cite journal}}: Cite journal requires |journal= (help)
  42. ^
    ISBN 9780891181040. Cited in Glaser 2007
    .
  43. .
  44. ^ Lehmann, Johannes; Silva Junior, José; Rondon, Marco; Manoel Da Silva, Cravo; Greenwood, Jaqueline; Nehls, Thomas; Steiner, Christoph; Glaser, Bruno (1 January 2002). "Slash and Char: a feasible alternative for soil fertility management in the Central Amazon?". {{cite journal}}: Cite journal requires |journal= (help)
  45. ^ Günther, Folke. "Folke Günther on ecological design,thermodynamics of living systems,ecological engineering, nutrient recycling and oil depletion". www.holon.se. Retrieved 5 August 2018.
  46. ^ Wilson, Kelpie (1 February 2020). The Biochar Cookbook: Practical Guidelines and Recipes for Making and Using Biochar – Volume I. pp. 14–19.
  47. ISSN 0030-1299. Cited in Glaser 2007
    .
  48. .
  49. ^ Sombroek 1966, p. 283 Cited in Glaser 2007.
  50. ^ a b Lehmann, Johannes.som "Site Terra Preta de Índio - Soil Biogeochemistry", Cornell University.
  51. ^ Sombroek 1966; Smith, 1980; Kern and Kämpf, 1989; Sombroek, Nachtergaele & Hebel 1993; Glaser et al. 2007; Lehmann et al. 2007; Liang et al. 2006
  52. ^ Jean-François Ponge; Stéphanie Topoliantz; Sylvain Ballof; Jean-Pierre Rossi; Patrick Lavelle; Jean-Marie Betsch; Philippe Gaucher (2006). "Ingestion of charcoal by the Amazonian earthworm Pontoscolex corethrurus: a potential for tropical soil fertility" (.
  53. ^ Reddy, N. Sai Bhaskar. "Terra Preta Roof-Top Experiments".
  54. ^ a b Chia, C., Munroe, P., Joseph, S. and Lin, Y. 2010. Microscopic characterisation of synthetic Terra Preta. Soil Research, 48 (7), pp. 593—605
  55. ^ Lehmann, Johannes. "Terra Preta de Indio". www.css.cornell.edu. Retrieved 7 August 2018.
  56. ^ Adams, M. (2013), Securing soil through carbon., Sydney: University of Sydney
  57. S2CID 96404482
    .
  58. .
  59. ^ Mann, Charles C. (September 2008). "Our Good Earth". National Geographic Magazine. Archived from the original on 19 August 2008.
  60. ^ "Embrapa Amazônia Ocidental - Portal Embrapa". www.cpaa.embrapa.br. Retrieved 14 February 2018.
  61. ^ "Sachamama". Archived from the original on 25 January 2016. Retrieved 20 January 2016.
  62. ^ "Verfahren zur herstellung von humus- und nährstoffreichen sowie wasserspeichernden böden oder bodensubstraten für nachhaltige landnutzungs- und siedlungssysteme".
  63. PMID 20453341
    .

References

External links