ABSTRACT Currently in Brazil, large grain cultivation projects on Plinthosols are a reality, however, there is little or no knowledge of the real mechanism of formation of the plinthite feature, in addition to what is reported in the literature as being a product of oxidation-reduction processes of iron element. This study evaluates iron redoximorphic features and investigates their chemical and mineralogical composition in two profiles of Plinthosols from the Araguaia River plain (P1 and P2). The study strengthens the understanding […]

ABSTRACT Variations in chemical and mineralogical properties of a soil can occur at short vertical and horizontal distances. The objective of the present study was to evaluate the chemical and mineralogical soil properties of different aggregate classes from young (Ustrochrept) and highly weathered (Acrustox) soils from the state of Paraná, Brazil. Undisturbed blocks (0.20 ×0.20 ×0.20 m) of soils were separated into aggregate classes: Acrustox – 8.0-4.0 mm; 4-2 mm; 2.0-0.5 mm; 0.5-0.2 mm; and <0.2 mm; and Ustrochrept – […]

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 […]

In the geomorphological unit of the Coastal Tablelands of Brazil there is a predominance of cohesive soil horizons and some with the presence of cemented horizons, commonly of the fragipan type. These horizons interfere with water dynamics, root growth, and, consequently, mineral nutrition of plants. The objective of this study was to use selective dissolution to evaluate the participation of forms of Fe, Si, or Al, or their combination, in the cohesion or cementation or both of fragipans and cohesive […]

A good knowledge of the spatial distribution of clay minerals in the landscape facilitates the understanding of the influence of relief on the content and crystallographic attributes of soil minerals such as goethite, hematite, kaolinite and gibbsite. This study aimed at describing the relationships between the mineral properties of the clay fraction and landscape shapes by determining the mineral properties of goethite, hematite, kaolinite and gibbsite, and assessing their dependence and spatial variability, in two slope curvatures. To this end, […]

The clay minerals goethite and hematite are iron oxides serving as indicators of the soil environment, with great influence on the soil physical and chemical properties. Knowledge of spatial patterns of these oxides can help understand the interrelationships of cause and effect with soil properties. In this sense, the quality of the spatial estimates can affect the results and consequently the interpretation of the spatial patterns. This study aimed to evaluate the performance of the geostatistical estimation methods by ordinary […]

The physical and chemical properties of a soil depend largely on its mineralogical constitution. Even over short horizontal distances, spatial variability may be high, and are best described by classical descriptive statistics associated with geostatistics. The objective of this study was to characterize the spatial variability of clay mineralogical properties of soils from the Guabirotuba formation, in the metropolitan region of Curitiba (PR), by classical descriptive statistics (especially coefficient of variation – CV) and geostatistics to propose more adequate sampling […]

The distribution of the clay fraction minerals depends on specific soil-environmental conditions. The study of the relationship between properties of these minerals and specific sites of landscape occurrence is important to understand the relationship between the mineralogy and other soil attributes. This study aimed to evaluate the degree of cristallinity of goethite, hematite, kaolinite and gibbsite and the spatial pattern in an Oxisol under sugar cane for 30 years. In a grid with regular 10 m – intervals, 119 samples […]

The no-tillage system (NT) affects the rate of soil processes, but little is known about its effect on the mineralogy of tropical and subtropical soils. This study aimed to evaluate the long-term effect of NT system on pedogenetic iron oxides and their relationship with soil organic matter (SOM) fractions. Soil samples were taken at 14 depths within the top 0,20 m soil layer from two clayey Oxisols under NT and conventional tillage (CT) systems of the experimental areas located near the […]

There have been several papers in the literature studying the genesis and consequences of particles cohesion in Argisols (Ultisols) and Latosols (Oxisols) from the Brazilian Inner and Coastal Plains. Just a few, however, provide insights into the clay fraction mineralogy, specially, the iron oxides complete characterization. The objective of this study was to investigate the chemical and crystallographic characteristics of iron oxides in red and yellow soils derived from the sediments of the Barreiras Formation or Pre-Cambrian rocks in the […]