Tebuthiuron adsorption was determined in samples from 0-10 to 10-20 cm layers of three soils from the county of Ribeirão Preto (SP)-Brazil: Quartzarenic Neosol (Entisol), Red Latosol dystrofic and Red Latosol dystroferric (Oxisols). Sorption data were obtained by batch equilibrium and fitted to four adsorption models: Freundlich, linear, Langmuir and Lambert. Several statistical criteria were applied for selection among these isotherms. Freundlich model showed the best fit to the data. Kd values ranged from 0.723 to 2.573 L kg-1, and […]

Adsorption-desorption reactions of lead in soils are affected by surface chemistry and solution composition. This study evaluated the effect of pH upon lead adsorption-desorption by A-horizon samples of Brazilian Oxisols. Soil suspension was previously titrated with either 7 mmol HNO3 or saturated Ca(OH)2 to determine the amount of acid or base necessary for pH adjustment. The effect of pH on Pb adsorption was evaluated after a 72 h-reaction of the soil samples with 0.15 mmol L-1 Pb(NO3)2 at pH 4.5, 5.5, and 6.5, using […]

Little is known about the effect of mafic parent materials on soil genesis in the humid “Zona da Mata”, Minas Gerais, although there are many detailed studies on soils developed from felsic to mesocratic gneiss, notably Latosols and terrace Podzolic soils. To fill this gap, soils in two topolitosequences, comprising A and B or A and C horizons, were sampled and studied. In the first topolitosequence, at Serra de Guiricema, a Red-Yellow Latosol on the top, a Argilluvic Chernosol, a […]

Total soil lead (Pb) content along with the sorption capacity of Pb in soils are important parameters for risk assessment studies of Pb in the environment. This experiment used A-horizon samples of 17 Oxisols from all Brazilian regions to evaluate their total Pb content as well as their Pb maximum adsorption capacities (PbMAC). The total soil Pb content varied from 6.14 to 30.55 mg kg-1, averaging 18.00 mg kg-1. The highest total soil Pb contents were found for soils of the southern and southeastern regions, […]

Morphological, physical and chemical data of 58 soil profiles of Ferralsols and low activity clay Cambisols, Lixisols, Acrisols and Nitisols and of Alisols of the International Soil Reference and Information Centre (ISRIC) collection, described and sampled in eighteen different countries of tropical and subtropical regions, were selected to analyse their consistency and, or, variability and to search for properties to better describe and differentiate them. The soil profile descriptions were based on the guidelines of FAO and the FAO endorsed […]

The state of Rio de Janeiro, Brazil, is characterized by three main geomorphologic formations, the landform constituted by crystalline rocks, exposed or covered by their alteration products; coastal tablelands, formed by Barreiras Formation Tertiary sediments; and alluvial floodplain sediments of Quaternary age. Differences between parent material and topography and their influence on soil genesis have been the main subject of studies in Rio de Janeiro. The objective of this study was to analyze the behavior of extractable forms of iron, […]

High phosphate adsorption in oxidic tropical soils changes the charge balance on the surface of particles and can increase dispersion. Consequently, it can affect pore size distribution, aggregate stability and susceptibility to compaction. In order to measure the effect of phosphate sorption on compression curves and consistence limits, a Dark-Red Latosol (LE) (very fine, allitic, isothermic Typic Hapludox) and a Cambisol (C) (very fine, isothermic Oxic Distropept) were sampled at 0-3 and 27-30 cm depth, at Campos da Mantiqueira, Minas […]

The experiment was conducted under greenhouse conditions at the Federal University of Uberlândia, State of Minas Gerais, Brazil, from March to August 1995. The purpose of this study was to determine if suppression of seven soil classes could inhibit infection of soybeans by R. solani, and how suppression might relate to the physical, chemical and biological characteristics of these soils. After infesting soils with R. solani, grown on autoclaved sorghum grains, disease intensity increased in soybean seedlings grown in all […]