Gênese de ferri-argilãs em horizontes B texturais de uma seqüência de solos sobre diabásio em Piracicaba (SP)

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The soil structure transformation from ferralic to nitic horizons was studied in a toposequence on quaternary red clayey sediments and diabase in Piracicaba (SP), Brazil. Morphological and micromorphological studies, image analysis, soil water characteristic curves and monitoring of (total) soil water potential head were used. The presence of polyconcave vughs, clayskins and planar voids shows that the vertical and lateral transition and structural transformation from ferralic to nitic horizons is given by the coalescence of the microaggregates, probably due to tensions created in a drier period in the past. Changes to a more humid climate with a defined dry season and alternate drying and wetting cycles resulted in the fissuration of the previously coalesced material, forming polyhedral aggregates and microaggregates. Simultaneously, clay illuviation filled the voids and together with the compacting action of the biological activity of these soils contributed to the coalescence of microaggregates.

Section: Discussionmentioning

confidence: 91%

Soil structure transformations from ferralic to nitic horizons on a toposequence in southeastern Brazil

Cooper¹,

Vidal‐Torrado²,

Grimaldi

2010

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“…In addition to the close relationship between parent material and soil properties (Brilhante et al, 2017;Neves et al, 2018), the relief plays a key role in pedodiversity, since along the slopes, there may be mixtures of parent materials, conditioning the formation of soil with peculiar properties. It is possible to find the occurrence of Nitossolos distinct from those previously studied in other regions of Brazil (Cooper and Vidal-Torrado, 2000;Ferreira et al, 2003;Silva et al, 2009;Melo et al, 2010) The southern coastal region of Pernambuco, in addition to the estuarine environments, is formed by the Atlantic forest ecosystem, the natural vegetation of which is practically nonexistent. The area is mainly used for sugarcane cultivation, a large industrial park, and dense urban areas with a population of approximately 500,000 inhabitants (IBGE, 2010).…”

Section: Introductionmentioning

confidence: 84%

“…Basic and intermediate rocks are widely documented as the parent lithology for soils with a nitic horizon (Cooper and Vidal-Torrado, 2000;Cooper et al, 2010;Melo et al, 2010;Soil Survey Staff, 2014;De Wispelaere et al, 2015). The Nitossolos developed from basalt throughout Brazil (Brasil, 1972;Santos Filho et al, 1978;Araújo Filho et al, 2000;Tremocoldi, 2003;Oliveira et al, 2004;Neves et al, 2018) generally present values of Fe 2 O 3 (sulfuric digestion) above 18 % and are classified as Nitossolos Vermelhos or Brunos (Santos et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Genesis and Classification of Nitisols from Volcano-Sedimentary Lithology in Northeastern Brazil

Costa

Araújo

Neves

et al. 2019

On the southern coast of Pernambuco State (PE), Brazil, lithotypes of the Cabo Basin (volcanic and sedimentary rocks), in association with the relief, allow the determination of the dynamics of the formation of Nitossolos Háplicos (Nitisols), including those with high levels of exchangeable aluminum. The objective of this study was to evaluate the influence of lithological diversity (basalt and sedimentary siliciclastic rocks) on the morphological, physical, chemical, and mineralogical properties of Nitossolos Háplicos along a slope (P1-summit, P2-backslope, P3-footslope) on the southern coast of PE, in order to consider its genesis and the relation of soil properties to adjacent environments and to evaluate its framing within the Brazilian Soil Classification System (SiBCS). The interaction of lithology/soil permeability and climate indicate significant differences in the mineralogical composition and dynamics of soil chemical elements. The profiles P1 and P2 are subject to monosialitization, ferralitization, and alitization processes. All profiles showed high Fe contents (ferric soils) and clay fractions, consisting primarily of kaolinite, goethite, hematite, and gibbsite, as well as quartz and feldspar in the sand and silt fractions. However, smectite minerals (P3) are probably inherited from the sedimentary source material. In the conglomerate samples, under P3, biotite, muscovite, and plagioclase were identified. Allytic characteristics (P3) are probably associated with the weathering of aluminous smectite minerals. These properties distinguish these soils from adjacent Nitossolos and other Nitossolos in Brazil. For the classification of soils according to SiBCS, considering the high levels of Fe and Al, Nitossolo Háplico distroférrico (P1 and P2) and Nitossolo Háplico alitiférrico (P3) are suggested, and according to the World Reference Base of Soils (WRB), the soils are classified as Ferritic Nitisols.

“…According to Cooper & Vidal-Torrado (2000), the main processes that form textural B horizons are clay translocation and deposition in pores as illuvial cutans. Fedoroff & Eswaran (1985) also suggested that illuvial cutans are the main feature for classifying textural B horizons.…”

Section: Micromorphologymentioning

confidence: 99%

Highlands of the upper Jequitinhonha valley, Brazil: II - mineralogy, micromorphology, and landscape evolution¹

Bispo

Silva

Vidal‐Torrado

et al. 2011

SUMMARYPalm swanp formations, the so-called veredas, typically occur in the Brazilian biome known as "Cerrado" (savanna-like vegetation), especially on flattened areas or tablelands (chapadas). The aim of this study was to characterize the mineralogy and micromorphology of soil materials from a representative toposequence of the watershed of the vereda Lagoa do Leandro, located in Minas Novas, state of Minas Gerais, Brazil, on plains in the region of the upper Jequitinhonha valley, emphasizing essential aspects of their genesis and landscape evolution. The toposequence is underlain by rocks of the Macaúbas group and covered with detrital and metamorphic rocks (schists of Proterozoic diamictites). The soil profiles were first pedologically described; samples of the disturbed and undisturbed soils were collected from all horizons for further micromorphological and mineralogical analyses. The mineralogical analysis was mainly based on powder X ray diffractometry (XRD) and micromorphological descriptions of thin sections under a petrographic microscope. The soils from the bottom to the top of this toposequence were classified as: Typic Albaquult (GXbd), Xanthic Haplustox, gray color, here called "Gray Haplustox" ("LAC"), Xanthic Haplustox (LA) and Typic Haplustox (LVA). The clay mineralogy of all soils was found to be dominated by kaolinite. In soil of LA and LVA, the occurrence of goethite, gibbsite, and anatase was evidenced; "LAC" also contained anatase and the GXbd, illite, anatase, and traces of vermiculite. The micromorphological analyses of the LVA, LA and "LAC" soils showed the prevalence of a microaggregate-like or granular microstructure,