Mineralogia, morfologia e análise microscópica de solos do bioma cerrado

Abstract

RESUMOAs características macro e micromorfológicas dos horizontes diagnósticos superficiais e subsuperficiais de Latossolos e Neossolos Quartzarênicos das superfícies Sul-Americana e Velhas foram estudadas em perfis sob cobertura de vegetação nativa, visando estabelecer um referencial para futuras comparações com áreas similares sob constante intervenção antrópica em termos de sustentabilidade. Com os solos referenciados por sub-região e pela superfície geomórfica que representam, três agrupamentos foram constituídos: Grupo 1: solos de textura argilosa a muito argilosa e hipo a mesoférricos; Grupo 2: solos de textura média a arenosa e hipoférricos, e Grupo 3: solos de textura argilosa a muito argilosa e férricos. O horizonte Bw dos Latossolos argilosos e muito argilosos estudados (Grupos 1 e 3), com relações cauliníticas/(caulinita + gibbsita) variando de 0,27 a 0,77, apresentaram grande coincidência de estrutura e microestrutura, respectivamente, forte muito pequena granular e de microagregados. Os solos do Grupo 2, Latossolos de textura média e um Neossolo

Teores de arsênio e cádmio em solos do bioma cerrado

“…Essas sub-regiões foram escolhidas não só com base na sua representatividade, mas também pelo fato de possuírem informação básica publicada como mapas de solo, estudos de gênese do solo etc. (Marques et al, 2004a,b;Gomes et al, 2004). Esses solos foram os mesmos utilizados nos estudos realizados por Marques et al (2004a,b), nos quais encontram-se as características químicas, físicas e mineralógicas das classes de solo estudadas.…”

Hydropedology of a High Tableland with Cerrado, Brazilian Central Plateau: the Frutal Catchment Case Study

“…In all soils, the groundmass consists of fine quartz grains (coarse material), and a reddish clay micromass, partially coating grains, with a gibbsite-hematite nature. In the same region, Gomes et al (2004) showed a very similar microstructure with interconnected (coalesced) granules, similar to soils P1 and P2, with zones of loose microaggregates, micromass, appearing mostly as grain coatings, indicating a mixture of quartz grains, and clays in the groundmass. Similar impacts of cultivation/ploughing on Ferralsols' microstructure were described by Marcelino et al (2010).…”

“…This results in a porostriated to granostriated b-fabrics under plane polarized light. Micromorphological results indicated evidences of compaction by intensive mechanization in patches of sandy soils, and the structural reorganization of P14, leading to coalescing aggregates and closed packing voids with lower macroporosity, becoming similar to clayey Ferralsols, as reported by Gomes et al (2004) and Silva and Castro (2015). Changes in soil structure due to land use can be detected by micromorphological studies and associated features, when comparing natural with compacted or degraded soil (Bullock et al, 1985).…”

Relations of Clay Fraction Mineralogy, Structure and Water Retention in Oxidic Latosols (Oxisols) from the Brazilian Cerrado Biome

“…They were formed under conditions of significant weathering-leaching, which contributed to their advanced degree of pedogenic development, resulting in a very simple mineralogy, in [76]. Their clay mineralogy consists basically of 1:1 clay minerals, mainly kaolinite (Si2Al2O5 (OH)4), iron oxides (hematite (Fe2O3) and goethite (FeOOH)) and aluminum oxides (gibbsite (Al(OH)3)) in different proportions, as well as quartz and other resistant minerals, in [16,38,39,44,46,54,65,73,74,75,76,77,83]. There are also registers in the clay fraction of some Latosols formed from rocks richer in iron, of maghemite (Fe2O3) as well as magnetite (Fe3O4) and ilmenite (FeTiO3) in the coarse fraction [93,97].…”

“…An indication of this resistance is the difficulty of evaluating the clay content in the field, requiring more time for reliable estimates, in [13]. This micro-aggregates resistance also manifests itself in the laboratory analysis of particle size distribution, mainly during the chemical and mechanical soil dispersion, in [38,39,63,99].…”