Andic properties in soils with histic horizon “O” in the highlands of Southern Brazil

ABSTRACT Soils with andic properties are characterized by a low apparent density, variable charges, large amounts of allophanes, imogolite, ferrihydrite, and/or organo-metallic complexes with Al, and present high phosphate retention. Soils derived from non-pyroclastic materials rich in silicates, fo...

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Main Authors: Jaime Barros dos Santos Junior, Jaime Antonio de Almeida
Format: Article
Language:English
Published: Sociedade Brasileira de Ciência do Solo 2021-04-01
Series:Revista Brasileira de Ciência do Solo
Subjects:
Online Access:http://www.scielo.br/pdf/rbcs/v45/1806-9657-rbcs-45-e0200152.pdf
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author Jaime Barros dos Santos Junior
Jaime Antonio de Almeida
author_facet Jaime Barros dos Santos Junior
Jaime Antonio de Almeida
author_sort Jaime Barros dos Santos Junior
collection DOAJ
description ABSTRACT Soils with andic properties are characterized by a low apparent density, variable charges, large amounts of allophanes, imogolite, ferrihydrite, and/or organo-metallic complexes with Al, and present high phosphate retention. Soils derived from non-pyroclastic materials rich in silicates, formed under a cold and humid climate, a large amount of organic carbon, acid weathering, andic properties can manifest when a large amount of Al is present in the form of organo-metallic complexes. This study aimed to evaluate the characteristics and geographical expression of soils with such properties in areas of altitude in the extreme south of Brazil, on the escarpment edges of the Serra Geral Formation, under a cold and humid climate. The sampling points were selected based on environmental characteristics such as geomorphology, geology, the coloration of the superficial horizon of the soil, and position in the landscape, covering a linear distance of approximately 185 km at the escarpment edge between the states of Santa Catarina and Rio Grande do Sul. Soil samples were described and collected from ten soils with histic horizon O, three soils with humic horizon, and one soil with histic horizon H. The undisturbed soil samples were collected using volumetric metallic cylinder to determine the soil bulk density. Organic matter, pH(H2O), P retention, and selective dissolutions of Al, Fe, and Si analyses were performed. The Cambissolos Hísticos and Organossolos Fólicos showed andic properties, while the Cambissolos Húmicos and Organossolo Háplico did not meet one or more criteria, as required by the Brazilian Soil Classification System and the World Reference Base for Soil Resources. The horizons with andic properties were classified as aluandic, based on the predominance of Al associated with organic complexes. The cold climate and high cloudiness of the highest altitude areas in the extreme south of Brazil, occurring in a narrow strip of the escarpment of the Serra Geral Formation in the states of Santa Catarina and Rio Grande do Sul, allow the formation of a constantly humid environment. This environment favors the acid weathering of the source material, accumulation of organic matter in the soil, and its stabilization by the formation of organo-metallic complexes, mainly Al-humus. The combination of these factors gives the soils with histic horizons O a low bulk density, high phosphate retention, and Alo + ½Feo ≥2 % values, meeting the criteria required for andic properties.
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spelling doaj.art-a400eb74608b46a1a8cbb2849792d8382022-12-22T04:09:16ZengSociedade Brasileira de Ciência do SoloRevista Brasileira de Ciência do Solo1806-96572021-04-014510.36783/18069657rbcs20200152Andic properties in soils with histic horizon “O” in the highlands of Southern BrazilJaime Barros dos Santos Juniorhttps://orcid.org/0000-0002-2933-8764Jaime Antonio de Almeidahttps://orcid.org/0000-0001-5808-9421ABSTRACT Soils with andic properties are characterized by a low apparent density, variable charges, large amounts of allophanes, imogolite, ferrihydrite, and/or organo-metallic complexes with Al, and present high phosphate retention. Soils derived from non-pyroclastic materials rich in silicates, formed under a cold and humid climate, a large amount of organic carbon, acid weathering, andic properties can manifest when a large amount of Al is present in the form of organo-metallic complexes. This study aimed to evaluate the characteristics and geographical expression of soils with such properties in areas of altitude in the extreme south of Brazil, on the escarpment edges of the Serra Geral Formation, under a cold and humid climate. The sampling points were selected based on environmental characteristics such as geomorphology, geology, the coloration of the superficial horizon of the soil, and position in the landscape, covering a linear distance of approximately 185 km at the escarpment edge between the states of Santa Catarina and Rio Grande do Sul. Soil samples were described and collected from ten soils with histic horizon O, three soils with humic horizon, and one soil with histic horizon H. The undisturbed soil samples were collected using volumetric metallic cylinder to determine the soil bulk density. Organic matter, pH(H2O), P retention, and selective dissolutions of Al, Fe, and Si analyses were performed. The Cambissolos Hísticos and Organossolos Fólicos showed andic properties, while the Cambissolos Húmicos and Organossolo Háplico did not meet one or more criteria, as required by the Brazilian Soil Classification System and the World Reference Base for Soil Resources. The horizons with andic properties were classified as aluandic, based on the predominance of Al associated with organic complexes. The cold climate and high cloudiness of the highest altitude areas in the extreme south of Brazil, occurring in a narrow strip of the escarpment of the Serra Geral Formation in the states of Santa Catarina and Rio Grande do Sul, allow the formation of a constantly humid environment. This environment favors the acid weathering of the source material, accumulation of organic matter in the soil, and its stabilization by the formation of organo-metallic complexes, mainly Al-humus. The combination of these factors gives the soils with histic horizons O a low bulk density, high phosphate retention, and Alo + ½Feo ≥2 % values, meeting the criteria required for andic properties.http://www.scielo.br/pdf/rbcs/v45/1806-9657-rbcs-45-e0200152.pdfpedologypedogenesisorganic matterorgano-metallic complexes
spellingShingle Jaime Barros dos Santos Junior
Jaime Antonio de Almeida
Andic properties in soils with histic horizon “O” in the highlands of Southern Brazil
Revista Brasileira de Ciência do Solo
pedology
pedogenesis
organic matter
organo-metallic complexes
title Andic properties in soils with histic horizon “O” in the highlands of Southern Brazil
title_full Andic properties in soils with histic horizon “O” in the highlands of Southern Brazil
title_fullStr Andic properties in soils with histic horizon “O” in the highlands of Southern Brazil
title_full_unstemmed Andic properties in soils with histic horizon “O” in the highlands of Southern Brazil
title_short Andic properties in soils with histic horizon “O” in the highlands of Southern Brazil
title_sort andic properties in soils with histic horizon o in the highlands of southern brazil
topic pedology
pedogenesis
organic matter
organo-metallic complexes
url http://www.scielo.br/pdf/rbcs/v45/1806-9657-rbcs-45-e0200152.pdf
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