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| Registros recuperados: 11 | |
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| Fernandes,Kathleen Lourenço; Ribon,Adriana Aparecida; Marques Junior,José; Bahia,Angélica Santos Rabelo de Souza; Tavares Filho,João. |
| Abstract: The objective of this work was to estimate the iron oxide contents (hematite and goethite) and to characterize the color and the spectral and magnetic signatures of Cerrado soils in the state of Goiás, Brazil. Six Oxisols and one Inceptisol were studied. Spectral and magnetic signatures were determined by diffuse reflectance spectroscopy (DRS) and magnetic susceptibility, respectively. Then, the spectral curves and the second derivative calculations were used to determine hematite and goethite contents, as well as soil color after conversion into tristimulus values. Hematite and goethite contents were also obtained by x-ray diffractometry, and soil color was also defined in the field (Munsell color chart). The values for the isomorphic... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Diffuse reflectance spectroscopy; Goethite; Hematite; Magnetic susceptibility; Oxisols. |
| Ano: 2017 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2017001000923 |
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| Camêlo,Danilo de Lima; Ker,João Carlos; Fontes,Maurício Paulo Ferreira; Corrêa,Marcelo Metri; Costa,Antonio Carlos Saraiva da; Melo,Vander Freitas. |
| 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 Rhodic Oxisols along with a Mesoferric Typic Oxisol originating from basalt, gabbro, tuffite, amphibolite and itabirite in Minas Gerais. The selected soils have taxonomic identities up to the fourth categorical level of the Brazilian System of... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Hematite; Maghemite; Crystallographic characteristics; Al-substitution; Selective dissolution. |
| Ano: 2017 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832017000100413 |
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| Camargo,Livia Arantes; Marques Júnior,José; Pereira,Gener Tadeu. |
| 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, two 100 × 100 m grids were used to establish a total of 121 regularly spaced georeferenced sampling nodes 10 m apart. Samples were collected from the layer 0.0-0.2 m and analysed for iron oxides, and kaolinite and... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Iron oxides; Kaolinite; Gibbsite; Goethite; Hematite; Relief. |
| Ano: 2013 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832013000200001 |
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| Bahia,Angélica Santos Rabelo de Souza; Marques Júnior,José; Panosso,Alan Rodrigo; Camargo,Livia Arantes; Siqueira,Diego Silva; Teixeira,Daniel De Bortoli; Scala Júnior,Newton La. |
| Soil CO2 emission (FCO2) is one of the main sources of carbon release into the atmosphere. Moreover, FCO2 is related to soil attributes governing the transfer of gases from soil to the atmosphere. This study aimed firstly to describe the spatial variability of hematite (Hm), goethite (Gt), iron extracted with sodium dithionite-citrate-bicarbonate (Fed) contents, soil CO2 emission (FCO2) and free-water porosity (FWP) and secondly, to develop statistical models to predict the above mentioned factors in an Oxisol cultivated under manual harvesting of sugarcane (Saccharumspp.) in southeastern Brazil. The study was conducted on an irregular 50 m × 50 m grid containing 89 points, each 0.5-10 m apart. The 0-0.1 m soil layer at each sampling point was used to... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Hematite; Goethite; Soil respiration; Geostatistics; Cross-semivariograms. |
| Ano: 2015 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162015000200157 |
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| Inda,Alberto Vasconcellos; Torrent,José; Barrón,Vidal; Bayer,Cimélio; Fink,Jessé Rodrigo. |
| Replacing conventional tillage (CT) with no-tillage (NT) management alters the pedoenvironment and the rate of topsoil processes, with possible effects on dissolution processes associated with iron oxides and therefore soil mineralogy. This study aimed to determine the effect of NT on the content and distribution of types of iron oxides in a Rhodic Paleudult in southern Brazil. Soil samples were collected at eight depths within the 0.00-0.80 m layer under CT and NT in a long-term experiment (21 years). Mineralogical identification was conducted by X-ray diffraction (XRD), and the Fe content related to specific types of iron oxides determined by selective dissolution and diffuse-reflectance spectroscopy. Kaolinite, quartz, goethite, hematite, and maghemite... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Dissolution; Ferrihydrite; Hematite; Maghemite; Soil management. |
| Ano: 2013 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162013000100008 |
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| Fink,Jessé Rodrigo; Inda,Alberto Vasconcellos; Tiecher,Tales; Barrón,Vidal. |
| ABSTRACT Continuous crop expansion has led to a growing demand for phosphate fertilizers. A sound knowledge of the dynamics of phosphorus, and its interaction with iron oxides and organic matter, can be useful to develop effective strategies for sustainable management, especially in a scenario of increasing shortage of mineral phosphate resources. In this paper, we review the relationship of phosphate to iron oxides and organic matter, and its effect on phosphorus availability. Crops typically obtain phosphate from weathered minerals and dissolved fertilizers. However, the amount of phosphorus present in the soil solution depends on the extent to which it is adsorbed or desorbed by iron oxides, which may be influenced by interactions with organic matter.... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Goethite; Hematite; Phosphorus adsorption; Phosphorus desorption; Organic carbon. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-70542016000400369 |
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| Registros recuperados: 11 | |
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