Terra Roxa

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Terra Roxa ([ ˈtɛxɐ ˈxɔʃɐ ], [ ˈtɛʀɐ ˈʀɔʃɐ ]; Portuguese for 'violet earth') is the traditional name for fertile reddish, mineral, silty - loamy soils of the humid tropics and subtropics of Brazil , which are made up of basic parent rocks ( basalt , " Diabase “, dolerite courses). Although Terras Roxas are sometimes referred to as "Terra Rossa", these soil types are not to be confused with the Terra Rossa , one for the Mediterranean Region typical of limestone emerged floor. Terras Roxas are originally forest soils, which today, due to their relatively high fertility, are sometimes used intensively for agriculture, especially for the cultivation of the important Brazilian export fruits coffee , cocoa and sugar cane . Their occurrence is limited to the outcrop of Precambrian ( cratonal ) crystalline complexes (including in the catchment area of ​​the Amazon ) and the distribution area of Mesozoic flood basalts , with the occurrences associated with the Paraná basalts in southeastern Brazil, in the states of Paraná , São Paulo and in the south of Minas Gerais , economically and also economically, are the most important.

Lower forms

“Latossolo Vermelho” forms the pavement of an unpaved road and the substrate for the adjacent green areas near Avaré , São Paulo

Terra Roxa was mainly defined by its origin from basic rocks and its reddish color, and in the absence of a more precise definition, according to modern knowledge, sometimes more, sometimes less different soil types have been subsumed under this term. Gutmans (1943) takes the name literally and understands by Terra Roxa exclusively the "quite unique" purple soils based on Paraná basalts in the state of São Paulo. In the second half of the 20th century there is often a differentiation into different sub-forms:

Terra Roxa Legitima ('Echte Terra Roxa', also dusky red latosol  ; originally a soil type of the "primitive" Brazilian soil classification system) has a relatively low base saturation (but at least 35% within the upper 125 cm) and a relatively high degree of weathering, that is, it is relatively strongly desilicated and enriched (ferralized) with iron (III) oxide (Fe 2 O 3 ) and aluminum oxide (Al 2 O 3 ), so-called sesquioxides . In the Brazilian soil classification it is assigned to the "Latossolos" and correlated with the Oxisols (more precisely: Eutrustox and Eutrorthox) of the USDA soil classification and the Ferralsols of the FAO soil classification and the WRB (cf. also laterite ). The problem with this type of soil is the fixation of phosphorus (also artificially added through fertilization ) in the form of poorly soluble iron phosphates that are therefore not available to plants .

Terra Roxa Estruturada has a relatively high base saturation (up to 99%) and a lower degree of weathering than the Terra Roxa Legitima. A very clayey B-horizon that goes back to Lessivierung is typical . It is classified under the "Argi (lo) ssolos" and "Nitosolos" of the Brazilian classification and with the Alfisols (more precisely: Tropudalf and Paleustalf) and Ultisols (more precisely: Rhodoustults and Palexerults) of the USDA soil classification and the Nitisols and Luvisols of the FAO - or WRB classification correlated. In Paraná, Terra Roxa Estruturada is preferably found in low areas (below 800 m) and is represented in higher terrain by so-called Terra Bruna Estruturada .

In the “primitive” Brazilian soil classification system, a distinction was made between Terra Roxa Misturada (a Rhodus valley in the USDA classification) and Terra Roxa da Campo as transitional forms to sandy soils, with an increasing proportion of sand or an increasing proportion of sandstones in the parent rock .

Individual evidence

  1. ↑ a b M. Gutmans: Rochas-mater da “terra roxa”. Bragantia. Vol. 3, No. 9, 1943, pp. 272-319, doi: 10.1590 / S0006-87051943000900001 (Portuguese with longer English abstract).
  2. ↑ a b c Luciano Farinha Watzlawick, Leif Nutto, Peter Spathelf, Albert Reif, Marcos Vinicius Winckler Caldeira, Carlos Roberto Sanquetta: The phytogeographical units of Paraná, Brazil. Silviculture Institute, Faculty of Forest and Environmental Sciences, Albert-Ludwigs-University Freiburg, 2003, urn : nbn: de: bsz: 25-opus-10366 , p. 11.
  3. ^ Majid Husain: Concise Geography. Tata McGraw-Hill, 2011, ISBN 978-0-07-107479-7 , pp. 8.27 f.
  4. ↑ a b c d e TT Cochrane, LG Sánchez, LG de Azevedo, JA Porras, CL Garver: Land in Tropical America - La Tierra en America Tropical - A Terra na América Tropical. Vol. 1. Centro Internacional de Agricultura Tropical (CIAT), Empresa Brasileira de Pesquisa Agropecuária - Centro de Pesquisa Agropecuária dos Cerrados (EMBRAPA-CPAC), Cali 1985, archive.org , p. 89 , p. 101 and Appendix 1 .
  5. ↑ a b c d Yasuo Kitagawa, Maria Regina Freire Möller: Comparative clay mineralogy of the “terra roxa estruturada” soil in the amazon region. Soil Science and Plant Nutrition. Vol. 25, No. 3, 1979, pp. 385-395, doi: 10.1080 / 00380768.1979.10433179 .
  6. ^ A b ACS da Costa, MR Nanni: Classification Systems: Brazil. Pp. 234-238 in: Rattan Lal (Ed.): Encyclopedia of Soil Science. 2nd edition. Volume 1. CRC Press / Taylor & Francis, 2006, ISBN 0-8493-3830-1 .
  7. ↑ a b c DD Richter, LI Babbar: Soil Diversity in the Tropics. Advances in Ecological Research. Vol. 21, 1991, pp. 315-389, doi: 10.1016 / S0065-2504 (08) 60100-2 , p. 337 (Table 3).
  8. ^ Friedrich Hackemann: The soil investigation and its methods in Brazil. Research reports of the state of North Rhine-Westphalia, No. 1022. Springer Fachmedien, Wiesbaden 1962, ISBN 978-3-663-03423-0 , p. 102 f.
  9. ↑ Jacob Bennema: Soils: Chemical Characteristics. Pp. 36-46 in: Paulo de T. Alvim, T. T. Kozlowski (Ed.): Ecophysiology of Tropical Crops. Academic Press, 1977, ISBN 0-12-055650-2 , p. 42 ff.