ABSTRACT Shrinkage capacity (caráter retrátil in Portuguese) is a new diagnostic characteristic recently introduced in the Brazilian System of Soil Classification (SiBCS) to indicate shrink and swell properties observed in subtropical soils from highland plateaus in southern Brazil, specifically in Oxisols with brown colors. In soils located in road cuts exposed to drying for some weeks, strong shrinkage of soil volume is observed in these soils, resulting in the formation of pronounced vertical cracks and large and very large prismatic […]

ABSTRACT Maghemite (γ-Fe2O3) and hematite (α-Fe2O3) are important iron oxides in Brazilian soils derived from basalt. Maghemite can transform into hematite when exposed to high temperatures. However, isomorphic substitution (e.g., Al3+) may largely influence this process. We analyzed the kinetics of thermal transformation of Al-maghemites into Al-hematites and some of its mineralogical aspects. Synthetic substituted maghemites with different degrees of Al-substitution (0.0, 1.0, 2.0, 2.9, 3.8, 5.6, 6.7, 10.0, 12.0, and 17.1 mol% Al) were subjected to a temperature of […]

ABSTRACT Despite the considerable amount of information on the mineralogical characteristics of pedogenic Fe oxides in Brazilian soils, there are few studies on Fe-rich soils developed from mafic rocks with taxonomic identities at lower categorical levels. This study evaluated the mineralogical characteristics of pedogenic Fe oxides in B horizons (Bw) of Fe-rich Oxisols developed from several mafic rocks in the state of Minas Gerais, Brazil. The Bw horizons were sampled at a 0.8-1.0 m depth in 13 Ferric and Perferric […]

ABSTRACT Burning is a common practice in tropical areas and related changes in mineralogy might affect the chemical and physical behavior of soils. Maghemite is a common iron oxide in soils formed from basic rocks in tropical regions. This mineral and hematite are the main pigments in these soils and exhibit high magnetization stemming from the precursor magnetite formed during the weathering process of primary minerals. The objective of the present study was to analyze changes in color, magnetic suceptibility […]

ABSTRACT Mehlich-1 soil extract is currently used in Rio Grande do Sul (RS) and Santa Catarina (SC) States, in Brazil, to evaluate soil phosphorus available to plants and Mehlich-1 is sensitive to soil buffering capacity. This limitation is overcome partly by soil separation into buffering classes based on soil clay content. However, soil clay content has some technical and operational limitations, such as the underestimation of soil clay levels in soils under no-till. The aim of this study was to […]

A queima da pastagem após o inverno é uma prática antiga em solos de altitude, que visa principalmente ao rebrote da vegetação. Entretanto, o impacto do manejo da pastagem na matéria orgânica do solo de Neossolo de altitude ainda é pouco conhecido. O presente trabalho propôs-se a investigar a composição e o teor de matéria orgânica em perfis de Neossolo da região de São José dos Ausentes, RS, e relacionar os resultados com a ocorrência de queimadas e com o […]

O arroz cultivado em regime de inundação pode apresentar sintomas de desordens nutricionais semelhantes àqueles descritos quando ocorre toxidez de ferro. Os sintomas não ocorrem com a mesma intensidade em todos os cultivares e têm sido mais freqüentes nos cultivares modernos. O objetivo do trabalho foi avaliar, em casa de vegetação, a capacidade das plantas em oxidar o Fe reduzido (Fe2+) sobre a superfície das raízes, comparando duas variedades de arroz com diferentes sensibilidades ao Fe2+ em solução (BR IRGA […]

Este trabalho objetivou avaliar quais parâmetros obtidos dos modelos de isotermas de Freundlich e Langmüir melhor descrevem a adsorção de metais pesados em solos intemperizados e identificar a relação entre os parâmetros selecionados e os atributos químicos, físicos e mineralógicos de 12classes de solo do Brasil. Os solos foram coletados pela EMBRAPA-CNPS em diversos levantamentos nas regiões: Sul, Sudeste e Norte do País. Avaliou-se, por meio da análise de trilha, o desdobramento do coeficiente de correlação entre variáveis dependentes, obtidas […]