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All publications of “Vander Freitas Melo”

5 results

Do Aggregate Size Classes of the Subsurface Soil Horizon Have Different Chemical/Mineralogical Properties?

Rolff Vladimir Mitton, Vander Freitas Melo ORCID logo , Volnei Pauletti


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 – […]

Identification of Heavy Metals in Crystals of Sand and Silt Fractions of Soils by Scanning Electron Microscopy (SEM EDS/WD-EPMA)

Araína Hulmnn Batista, Vander Freitas Melo, Robert Gilkes, Malcolm Roberts


ABSTRACT Studies of heavy metals are concentrate on clay fractions, but coarser fractions of the soil can constitute significant sources of structural forms of heavy metals. The aim of this study was to evaluate the occurrence of heavy metals in the structure of minerals of the sand and silt fractions of soils from three different parent materials (metamorphic rocks and granite) in southern Brazil using SEM/EDS – Scanning Electron Microscopy with Energy Dispersive Spectroscopy and with WD-EPMA – with Wavelength […]

Land Use and Changes in Soil Morphology and Physical-Chemical Properties in Southern Amazon

Vander Freitas Melo, Alessandro Góis Orrutéa, Antônio Carlos Vargas Motta, Samara Alves Testoni


ABSTRACT Many Amazonian farmers use the slash-and-burn method rather than fertilization for crop production. The aim of the present study was to evaluate changes in the morphological, physical, and chemical properties of naturally fertile Inceptisols after conversion from native forest to different uses in southern Amazonia, Brazil. Land covered by dense native forest (NF) was split into four areas of 1.0 ha each. Three areas were slashed and burned and then cultivated for 11 years with coffee (CO), secondary forest […]

Pedogenic Iron Oxides in Iron-Rich Oxisols Developed from Mafic Rocks

Danilo de Lima Camêlo, João Carlos Ker, Maurício Paulo Ferreira Fontes, Marcelo Metri Corrêa, Antonio Carlos Saraiva da Costa, Vander Freitas Melo


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 […]

Microwave Acid Extraction to Analyze K and Mg Reserves in the Clay Fraction of Soils

Araína Hulmann Batista, Vander Freitas Melo, Robert Gilkes


ABSTRACT: Extraction of K and Mg with boiling 1 mol L-1 HNO3 in an open system for predicting K and Mg uptake by plants is a method of low reproducibility. The aim of this study was to compare the extraction capacity of different acid methods relative to hydrofluoric acid extraction for K and Mg. A further objective was to develop a chemical extraction method using a closed system (microwave) for nonexchangeable and structural forms of these nutrients in order to […]