Gênese dos Latossolos Húmicos e sua relação com a evolução da paisagem numa área cratônica do Sul de Minas Gerais

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,

“…The micromorphological features of the horizons of these latosols are similar to those reported by Andrade et al (1997) and Silva & Vidal-Torrado (1999).…”

Section: Micromorphologysupporting

confidence: 88%

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

Bispo

Silva

Vidal‐Torrado

et al. 2011

“…Os fragmentos de carvão são semelhantes àqueles encontrados em microagregados de origem biológica de Latossolos com horizonte A húmico por Silva & Vidal-Torrado (1999). A presença de fragmentos de carvão maiores, soltos no fundo matricial, também ocorre (Figura 9a).…”

Section: Micromorfologiaunclassified

Mineralogia, morfologia e análise microscópica de solos do bioma cerrado

Gomes

Curi

Schulze

et al. 2004

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

“…Moreover, studies on the effects of different land uses on the properties of the Lh are scarce in the literature and mostly refer to the South and Southeast areas of Brazil (Silva, 1997;Silva & Vidal Torrado, 1999;Marques et al, 2011;Assis et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Humic Haplustox under different land uses in a high altitude environment in the Agreste region of Pernambuco, Brazil

Araújo

Ribeiro

Corrêa

et al. 2014

SUMMARYThe Garanhuns Plateau in the Agreste region of the State of Pernambuco, Brazil is characterized by humid climatic conditions due to orographic rains, unlike the surrounding semiarid region. These soils are subjected to intense agricultural use and are extremely important for the regional economy. This study was carried out in the municipality of Brejão in the Agreste region with the aim of assessing changes in humic Haplustox soils subjected to different land uses. Four plots with different vegetation covers (native forest, secondary shrubby vegetation (capoeira), traditional cropping system, and planted pasture) were selected, and samples were taken from a soil profile and four small pits surrounding it at each site. Physical and chemical properties were assessed, including aggregate stability, humic organic fractions, and a microbiological evaluation through determination of basal respiration, microbial biomass carbon, and metabolic quotient. The soils under study showed physical and chemical properties typical of a Haplustox, such as low nutrient content, low cation exchange capacity, and high levels of acidity and Al saturation. The total organic carbon (TOC) contents were high regardless of the type of land use. Aggregates < 2 mm were dominant in all the conditions under study. The TOC content was higher in the soil under capoeira, 43.91 g kg -1 on the surface, while 34.36 and 33.43 g kg -1 of TOC were observed in the first layer of forest and pasture soils, respectively. While the microbial biomass C (MBC) was greater than 700 mg kg -1 in the forest and pasture areas (in the 0-5 cm layer), and 588 mg kg -1 in the soil under capoeira, these numbers were not statistically different. In the cultivated soil area, there was a reduction of around 28 % in TOC and MBC contents. Agricultural activity contributed to degradation of the humic 1338 horizon, as can be seen from a significant decrease in the TOC and changes in the relative distribution of the humic fractions. In contrast, aggregate stability was not altered as a function of the different land uses; the soil under planted pasture and capoeira were similar to the soil under native forest. Humin was the most important humified fraction for C reserves, contributing over 40 % of the TOC in these soils.Index terms: land use, highland soils, humic substances, aggregate stability, microbial biomass C. RESUMO: LATOSSOLOS AMARELOS HÚMICOS SOB DIFERENTES TIPOS DE UTILIZAÇÃO EM UM AMBIENTE ALTIMONTANO NO AGRESTE DE PERNAMBUCOO Planalto de Garanhuns, no Agreste de Pernambuco, destaca-se por apresentar características climáticas privilegiadas, favorecidas pelas chuvas orográficas, distinguindose da região semiárida circundante. Essas áreas mais úmidas são conhecidas como "brejos de altitude" e intensamente utilizadas e importantes para a economia regional. Este trabalho foi desenvolvido no município de Brejão, Agreste de Pernambuco, com o objetivo de identificar alterações nos atributos de Latossolos Amarelos Húmicos, submetidos às diferentes formas de uso do s...