Teógenes Oliveira | Universidade Federal de Viçosa (original) (raw)

Papers by Teógenes Oliveira

Research paper thumbnail of Soil physical quality of Luvisols under agroforestry, natural vegetation and conventional crop management systems in the Brazilian semi-arid region

Geoderma, 2011

The imposition of agricultural systems changes the natural equilibrium of the soil to an extent t... more The imposition of agricultural systems changes the natural equilibrium of the soil to an extent that it becomes dependant on management practices and soil resilience. Agroforestry systems (AFs) mimic characteristics of natural ecosystems such as multistrata canopy and deep rooting and may minimize the consequences of these changes by providing soil protection and maintenance of conditions similar to those under

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Research paper thumbnail of Water-dispersible clay after wetting and drying cycles in four Brazilian oxisols

Soil & Tillage Research, 2005

Widespread intensive land use in the seasonal tropics can damage the physical stability of aggreg... more Widespread intensive land use in the seasonal tropics can damage the physical stability of aggregates. Similar damage can be expected from wetting and drying cycles causing aggregate fragmentation and, consequently, leading to an increase in their specific area and exposure of internal electric charges. Thus, we hypothetised that the influence of wetting and drying cycles is dependent on the mineralogical

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Research paper thumbnail of Variabilidade espacial da produtividade do meloeiro em áreas de cultivo fertirrigado

Horticultura Brasileira, 2005

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Research paper thumbnail of Causas da variação em produtividade e qualidade do melão em um Latossolo Vermelho-Amarelo fertirrigado

Ciencia Rural, 2006

This work was carried out in Mossoró, RN, Brazil, with the objective of identifying soil and fert... more This work was carried out in Mossoró, RN, Brazil, with the objective of identifying soil and fertirrigation variables influencing melon yield and quality. Variables determinated were: yield (export and marketable type); quality (total soluble solids content and pulp firmness); fertirrigation (emitter discharge rate, elevation, distance to water inlet and fertilizer amount); soil chemical properties (pH, organic matter, Ca, Mg, K,

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Research paper thumbnail of Assessment of Soil Moisture by Family Farmers Under Multi-Cropping Systems in a Semiarid Region

Agroecology and Sustainable Food Systems, 2015

ABSTRACT Sustainable practices are key factors in the advancement of environmental protection in ... more ABSTRACT Sustainable practices are key factors in the advancement of environmental protection in agroecosystems, especially if these systems are situated in degraded and vulnerable areas, such as semiarid regions. One sustainable practice developed primarily in tropical farms is the use of a multi-cropping system. This system was applied using participatory approaches by family farmers from a semiarid region of Brazil and evaluated based on the perception and monitoring of the farmers, particularly the soil moisture enhancement in their productive areas. Thus, this study aimed to evaluate the impact of management practices on soil moisture in multi-cropping areas using an alternative method, based on the standard method, developed and applied by farmers in the field. In addition, the soil moisture alterations in multi-cropping systems were evaluated considering the water retention curve and the soil moisture monitoring in situ. We concluded that conservative practices in multi-cropping systems do contribute to water conservation. Furthermore, the establishment of a methodology to evaluate multi-cropping systems directly in the field by farmers is an important strategy to show to the farmers’ results that confirm the importance of the practices developed by them to maintain good production and general benefits to the environment.

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Research paper thumbnail of Variabilidade espacial da qualidade de frutos de melão em áreas fertirrigadas

Horticultura Brasileira, 2005

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Research paper thumbnail of Soil Organic Carbon and Nitrogen Stocks under Tropical Organic and Conventional Cropping Systems in Northeastern Brazil

Communications in Soil Science and Plant Analysis, 2009

Soil organic matter (SOM) is an essential ecosystem component whose dynamics are affected by soil... more Soil organic matter (SOM) is an essential ecosystem component whose dynamics are affected by soil management practices. To evaluate the impact of two agricultural systems (organic and conventional) on soil organic carbon (C) and nitrogen (N) stocks in a sandy soil, samples were collected from the Amway Nutrilite Brazil farm and from the Central Pivot Horticultural Farmers Association farm, both

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Research paper thumbnail of Indicadores de qualidade do solo em sistemas de cultivo orgânico e convencional no semi-árido cearense

Revista Brasileira de Ciência do Solo, 2007

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Research paper thumbnail of Biodiversidade em sistemas agroecológicos no município de Choró, CE, Brasil

Ciencia Rural, 2009

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Research paper thumbnail of RELATIONSHIP BETWEEN MAGNETIZATION AND TRACE ELEMENTS CONTENT OF BRAZILIAN SOILS FROM DIFFERENT PARENT MATERIALS

Soil Science, 2000

ABSTRACT Magnetic minerals are important in some Brazilian soils and they are a possible source o... more ABSTRACT Magnetic minerals are important in some Brazilian soils and they are a possible source of trace elements, especially in the highly weathered soils. The purpose of this investigation was thus to determine the trace element content in the magnetically separated sand, silt, and clay fractions from soils of different lithological origins in order to test the hypothesis that higher levels of magnetization are directly proportional to the contents of these elements. To accomplish this objective, the samples were dissolved by concentrated HCl/HF/HClO4 acid attack, and the contents of Cd, Cr, Cu, Ni, Pb, Zn, Zr, and V were analyzed by atomic emission spectroscopy with inductively coupled plasma (ICP-AES). The contents of trace elements in the total, magnetic and nonmagnetic sand, silt, and clay fractions were within the normal range presented by whole soils with the exception of Cd, which was higher. Magnetization (σs) of the total, magnetic and nonmagnetic soil fractions was evaluated with a special analytical balance. The σs values were higher for sand and lower for silt and clay fractions. The magnetically concentrated fractions gave results with variation in the same fashion but reaching higher values. The relationship between trace elements in soil fractions and magnetization, studied by correlation analysis, gave higher and more significant correlation coefficients when a soil derived from itabirite was excluded from the analysis. Because itabirite and mafic rocks have high magnetization, the correlation result demonstrates that there is a strongly significant association between magnetization and trace element contents for the soils derived from mafic rocks. Analysis of variance showed that there were significant differences between trace element contents of the magnetic compared with the nonmagnetic fractions of the soils derived from mafic rocks, especially in their sand and silt fractions. Tukey's test for comparison of means showed that mafic rocks have a higher content of trace elements compared with the other parent materials. The results obtained confirm the geochemical affinity of trace elements and the components of the magnetic fraction of the soils derived from the mafic rocks, mainly for sand and silt fractions, where higher contents of the investigated trace elements were observed.

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Research paper thumbnail of Produção de serapilheira e ciclagem de nutrientes na cultura do cajueiro anão precoce

Revista Árvore, 2008

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Research paper thumbnail of Metais pesados como indicadores de materiais de origem em uma topolitoseqüência do Triângulo Mineiro, Estado de Minas Gerais

Pesquisa Agropecuária Brasileira, 1999

ABSTRACT

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Research paper thumbnail of Phosphorus fractionation in a sandy soil under organic agriculture in Northeastern Brazil

Geoderma, 2009

This work aimed to evaluate the impacts of the organic fertilization and the use of green manure ... more This work aimed to evaluate the impacts of the organic fertilization and the use of green manure (GrM) on the different soil P fractions in areas under organic agriculture in the municipality of Ubajara, state of Ceará, Brazil. The work was carried out in an organically cultivated farm situated in the Ubajara municipality, state of Ceará, Brazil. Soil samples of

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Research paper thumbnail of Magnetic separation and evaluation of magnetization of Brazilian soils from different parent materials

Geoderma, 2000

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Research paper thumbnail of Soil physical quality of Luvisols under agroforestry, natural vegetation and conventional crop management systems in the Brazilian semi-arid region

Geoderma, 2011

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Research paper thumbnail of Morpho-physiological responses of cowpea leaves to salt stress

Brazilian Journal of Plant Physiology, 2006

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Research paper thumbnail of Sediment, nutrient and water losses by water erosion under agroforestry systems in the semi-arid region in northeastern Brazil

Agroforestry Systems, 2010

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Research paper thumbnail of Organic carbon pools in a Luvisol under agroforestry and conventional farming systems in the semi-arid region of Ceará, Brazil

Agroforestry Systems, 2007

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Research paper thumbnail of Organic matter and phosphorus fractions in irrigated agroecosystems in a semi-arid region of Northeastern Brazil

Agriculture, Ecosystems & Environment, 2010

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Research paper thumbnail of Geochemistry and spatial variability of metal(loid) concentrations in soils of the state of Minas Gerais, Brazil

The Science of the total environment, 2015

Since 2009 a policy has been implemented in Brazil to establish the natural concentrations of pot... more Since 2009 a policy has been implemented in Brazil to establish the natural concentrations of potentially toxic substances in soil for each state. Historically a 'mining state', Minas Gerais established a Quality Reference Value for metal(loid)s for all of the soils in the state. To successfully establish these values it is important to study the spatial geochemical diversity for the state. In this context, the objectives of this work are: (1) to evaluate the natural concentrations of metal(loid)s in pristine Minas Gerais soils and (2) to interpret the spatial variability in concentration of these elements. The 0-20 cm layer of soils was sampled for 697 georeferenced sites including the main geological materials and soil groups. Soil properties were analyzed according to methodologies suitable for Brazilian soils. The concentration of metal(loid)s was determined by acid extraction according to EPA 3051A. Descriptive statistics, Pearson correlation and spatial variability ana...

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Research paper thumbnail of Soil physical quality of Luvisols under agroforestry, natural vegetation and conventional crop management systems in the Brazilian semi-arid region

Geoderma, 2011

The imposition of agricultural systems changes the natural equilibrium of the soil to an extent t... more The imposition of agricultural systems changes the natural equilibrium of the soil to an extent that it becomes dependant on management practices and soil resilience. Agroforestry systems (AFs) mimic characteristics of natural ecosystems such as multistrata canopy and deep rooting and may minimize the consequences of these changes by providing soil protection and maintenance of conditions similar to those under

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Research paper thumbnail of Water-dispersible clay after wetting and drying cycles in four Brazilian oxisols

Soil & Tillage Research, 2005

Widespread intensive land use in the seasonal tropics can damage the physical stability of aggreg... more Widespread intensive land use in the seasonal tropics can damage the physical stability of aggregates. Similar damage can be expected from wetting and drying cycles causing aggregate fragmentation and, consequently, leading to an increase in their specific area and exposure of internal electric charges. Thus, we hypothetised that the influence of wetting and drying cycles is dependent on the mineralogical

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Research paper thumbnail of Variabilidade espacial da produtividade do meloeiro em áreas de cultivo fertirrigado

Horticultura Brasileira, 2005

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Research paper thumbnail of Causas da variação em produtividade e qualidade do melão em um Latossolo Vermelho-Amarelo fertirrigado

Ciencia Rural, 2006

This work was carried out in Mossoró, RN, Brazil, with the objective of identifying soil and fert... more This work was carried out in Mossoró, RN, Brazil, with the objective of identifying soil and fertirrigation variables influencing melon yield and quality. Variables determinated were: yield (export and marketable type); quality (total soluble solids content and pulp firmness); fertirrigation (emitter discharge rate, elevation, distance to water inlet and fertilizer amount); soil chemical properties (pH, organic matter, Ca, Mg, K,

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Research paper thumbnail of Assessment of Soil Moisture by Family Farmers Under Multi-Cropping Systems in a Semiarid Region

Agroecology and Sustainable Food Systems, 2015

ABSTRACT Sustainable practices are key factors in the advancement of environmental protection in ... more ABSTRACT Sustainable practices are key factors in the advancement of environmental protection in agroecosystems, especially if these systems are situated in degraded and vulnerable areas, such as semiarid regions. One sustainable practice developed primarily in tropical farms is the use of a multi-cropping system. This system was applied using participatory approaches by family farmers from a semiarid region of Brazil and evaluated based on the perception and monitoring of the farmers, particularly the soil moisture enhancement in their productive areas. Thus, this study aimed to evaluate the impact of management practices on soil moisture in multi-cropping areas using an alternative method, based on the standard method, developed and applied by farmers in the field. In addition, the soil moisture alterations in multi-cropping systems were evaluated considering the water retention curve and the soil moisture monitoring in situ. We concluded that conservative practices in multi-cropping systems do contribute to water conservation. Furthermore, the establishment of a methodology to evaluate multi-cropping systems directly in the field by farmers is an important strategy to show to the farmers’ results that confirm the importance of the practices developed by them to maintain good production and general benefits to the environment.

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Research paper thumbnail of Variabilidade espacial da qualidade de frutos de melão em áreas fertirrigadas

Horticultura Brasileira, 2005

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Research paper thumbnail of Soil Organic Carbon and Nitrogen Stocks under Tropical Organic and Conventional Cropping Systems in Northeastern Brazil

Communications in Soil Science and Plant Analysis, 2009

Soil organic matter (SOM) is an essential ecosystem component whose dynamics are affected by soil... more Soil organic matter (SOM) is an essential ecosystem component whose dynamics are affected by soil management practices. To evaluate the impact of two agricultural systems (organic and conventional) on soil organic carbon (C) and nitrogen (N) stocks in a sandy soil, samples were collected from the Amway Nutrilite Brazil farm and from the Central Pivot Horticultural Farmers Association farm, both

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Research paper thumbnail of Indicadores de qualidade do solo em sistemas de cultivo orgânico e convencional no semi-árido cearense

Revista Brasileira de Ciência do Solo, 2007

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Research paper thumbnail of Biodiversidade em sistemas agroecológicos no município de Choró, CE, Brasil

Ciencia Rural, 2009

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Research paper thumbnail of RELATIONSHIP BETWEEN MAGNETIZATION AND TRACE ELEMENTS CONTENT OF BRAZILIAN SOILS FROM DIFFERENT PARENT MATERIALS

Soil Science, 2000

ABSTRACT Magnetic minerals are important in some Brazilian soils and they are a possible source o... more ABSTRACT Magnetic minerals are important in some Brazilian soils and they are a possible source of trace elements, especially in the highly weathered soils. The purpose of this investigation was thus to determine the trace element content in the magnetically separated sand, silt, and clay fractions from soils of different lithological origins in order to test the hypothesis that higher levels of magnetization are directly proportional to the contents of these elements. To accomplish this objective, the samples were dissolved by concentrated HCl/HF/HClO4 acid attack, and the contents of Cd, Cr, Cu, Ni, Pb, Zn, Zr, and V were analyzed by atomic emission spectroscopy with inductively coupled plasma (ICP-AES). The contents of trace elements in the total, magnetic and nonmagnetic sand, silt, and clay fractions were within the normal range presented by whole soils with the exception of Cd, which was higher. Magnetization (σs) of the total, magnetic and nonmagnetic soil fractions was evaluated with a special analytical balance. The σs values were higher for sand and lower for silt and clay fractions. The magnetically concentrated fractions gave results with variation in the same fashion but reaching higher values. The relationship between trace elements in soil fractions and magnetization, studied by correlation analysis, gave higher and more significant correlation coefficients when a soil derived from itabirite was excluded from the analysis. Because itabirite and mafic rocks have high magnetization, the correlation result demonstrates that there is a strongly significant association between magnetization and trace element contents for the soils derived from mafic rocks. Analysis of variance showed that there were significant differences between trace element contents of the magnetic compared with the nonmagnetic fractions of the soils derived from mafic rocks, especially in their sand and silt fractions. Tukey's test for comparison of means showed that mafic rocks have a higher content of trace elements compared with the other parent materials. The results obtained confirm the geochemical affinity of trace elements and the components of the magnetic fraction of the soils derived from the mafic rocks, mainly for sand and silt fractions, where higher contents of the investigated trace elements were observed.

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Research paper thumbnail of Produção de serapilheira e ciclagem de nutrientes na cultura do cajueiro anão precoce

Revista Árvore, 2008

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Research paper thumbnail of Metais pesados como indicadores de materiais de origem em uma topolitoseqüência do Triângulo Mineiro, Estado de Minas Gerais

Pesquisa Agropecuária Brasileira, 1999

ABSTRACT

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Research paper thumbnail of Phosphorus fractionation in a sandy soil under organic agriculture in Northeastern Brazil

Geoderma, 2009

This work aimed to evaluate the impacts of the organic fertilization and the use of green manure ... more This work aimed to evaluate the impacts of the organic fertilization and the use of green manure (GrM) on the different soil P fractions in areas under organic agriculture in the municipality of Ubajara, state of Ceará, Brazil. The work was carried out in an organically cultivated farm situated in the Ubajara municipality, state of Ceará, Brazil. Soil samples of

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Research paper thumbnail of Magnetic separation and evaluation of magnetization of Brazilian soils from different parent materials

Geoderma, 2000

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Research paper thumbnail of Soil physical quality of Luvisols under agroforestry, natural vegetation and conventional crop management systems in the Brazilian semi-arid region

Geoderma, 2011

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Research paper thumbnail of Morpho-physiological responses of cowpea leaves to salt stress

Brazilian Journal of Plant Physiology, 2006

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Research paper thumbnail of Sediment, nutrient and water losses by water erosion under agroforestry systems in the semi-arid region in northeastern Brazil

Agroforestry Systems, 2010

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Research paper thumbnail of Organic carbon pools in a Luvisol under agroforestry and conventional farming systems in the semi-arid region of Ceará, Brazil

Agroforestry Systems, 2007

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Research paper thumbnail of Organic matter and phosphorus fractions in irrigated agroecosystems in a semi-arid region of Northeastern Brazil

Agriculture, Ecosystems & Environment, 2010

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Research paper thumbnail of Geochemistry and spatial variability of metal(loid) concentrations in soils of the state of Minas Gerais, Brazil

The Science of the total environment, 2015

Since 2009 a policy has been implemented in Brazil to establish the natural concentrations of pot... more Since 2009 a policy has been implemented in Brazil to establish the natural concentrations of potentially toxic substances in soil for each state. Historically a 'mining state', Minas Gerais established a Quality Reference Value for metal(loid)s for all of the soils in the state. To successfully establish these values it is important to study the spatial geochemical diversity for the state. In this context, the objectives of this work are: (1) to evaluate the natural concentrations of metal(loid)s in pristine Minas Gerais soils and (2) to interpret the spatial variability in concentration of these elements. The 0-20 cm layer of soils was sampled for 697 georeferenced sites including the main geological materials and soil groups. Soil properties were analyzed according to methodologies suitable for Brazilian soils. The concentration of metal(loid)s was determined by acid extraction according to EPA 3051A. Descriptive statistics, Pearson correlation and spatial variability ana...

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