Raphael Fernandes - Academia.edu (original) (raw)
Papers by Raphael Fernandes
Revista Árvore, 2018
The use of trees in integrated crop-livestock-forestry systems (ICLF) allows diversifying product... more The use of trees in integrated crop-livestock-forestry systems (ICLF) allows diversifying production, increasing profitability per area, and providing a higher animal comfort. However, the influence of tree component on soil chemical attributes in this system is still little studied. This study aimed to assess the effect of trees and sun-exposed faces to solar radiation on soil nutrient availability at different distances of tree rows in an integrated crop-livestock-forestry system. This study was carried out in the northern Mato Grosso State, Brazil, in the Cerrado - Amazon Forest transition region in an ICLF with the tree component formed by three eucalyptus rows. The assessment carried out in the second year of ICLF implantation considered the effect of tree distances (3, 6, 10, and 15 m) on two sun-exposed faces to solar radiation (north and south) on the main soil chemical attributes. Soil sampling was performed at depths of 0-0.05, 0.05-0.10, 0.10-0.20, and 0.20-0.30 m. The re...
Revista Árvore, 2018
Integrated crop-livestock-forest (iCLF) systems have gained prominence in the past decades as an ... more Integrated crop-livestock-forest (iCLF) systems have gained prominence in the past decades as an alternative of sustainable land use, particularly in regions in which there is pressure against agricultural expansion in protected ecosystems such as the Brazilian Amazon. In this context, the objective of this study is to evaluate the effects of one year of use of the iCLF system in the Cerrado/Amazon transition region to determine its impact on soil quality compared to other traditional land uses in the region (planted forest, crop, forage, and native forest). The results indicated that the iCLF system did not jeopardize the soil physical quality, and only the crop land use affected the soil physical attributes. The land uses with the lowest impact on the physical condition of the soil were the iCLF system and the planted forest.
The Science of the total environment, Jan 16, 2017
The objective of this study was to evaluate sediment, water and nutrient losses from different pa... more The objective of this study was to evaluate sediment, water and nutrient losses from different pasture managements in the Atlantic Rainforest biome. A field study was carried out in Alegre Espiríto Santo, Brazil, on a Xanthic Ferralsol cultivated with braquiaria (Brachiaria brizantha). The six pasture managements studied were: control (CON), chisel (CHI), fertilizer (FER), burned (BUR), plowing and harrowing (PH), and integrated crop-livestock (iCL). Runoff and sediment samples were collected and analyzed for calcium (Ca), magnesium (Mg), potassium (K), phosphorus (P) and organic carbon contents. Soil physical attributes and above and below biomass were also evaluated. The results indicated that higher water loss was observed for iCL (129.90mm) and CON (123.25mm) managements, and the sediment losses were higher for CON (10.24tha(-1)) and BUR (5.20tha(-1)) managements when compared to the other managements. Majority of the nutrients losses occurred in dissolved fraction (99% of Ca, 9...
CATENA, 2017
Knowledge on active-layer dynamics and permafrost distribution is of especial importance in Marit... more Knowledge on active-layer dynamics and permafrost distribution is of especial importance in Maritime Antarctica, where dramatic climate warming occurred in the last decades. Few long-term studies of active-layer temperatures in this region, and no one focus on recently deglaciated areas under paraglacial conditions. This paper analyses the long-term soil thermal regime of a warm-based glacial front site located at Low Head, King George Island. The monitoring system consists of soil temperature probes connected to a datalogger that recorded data at hourly intervals. We calculated the thawing days (TD), freezing days (FD), number of isothermal days (ID), number of freeze-thaw days (FTD), thawing degree days (TDD), freezing degree days (FDD), and the apparent thermal diffusivity (ATD). The results indicate that active layer thermal regime at Low Head is similar to other periglacial environments from Maritime Antarctica, with differences associated with the influence from the nearby warm-based glacier. Surface temperatures show greater variations during the summer resulting in frequent freeze and thaw cycles, mainly (1 cm and 10 cm). The temperature profile during the studied period indicates that the active layer thickness reached a maximum of 106 cm on February 7th 2015. Soil temperature buffering was limited by the low snow cover, low soil moisture, and absence of vegetation. Based on the high interannual variability detected during the five years monitoring run, we stress that longer monitoring periods are necessary for a more detailed knowledge on how permafrost respond to climate changes in this rapidly warming zone.
Revista da Faculdade de Odontologia - UPF, Jul 17, 2012
Cirurgiã-dentista, aluna do curso de mestrado em Biologia Oral e do curso de especialização em Od... more Cirurgiã-dentista, aluna do curso de mestrado em Biologia Oral e do curso de especialização em Odontologia Legal, Faculdade de Odontologia de Ribeirão Preto (USP). ** Cirurgião-dentista, aluno do curso de mestrado em Biologia Oral, Faculdade de Odontologia de Ribeirão Preto (USP).
Revista Ceres, 2015
ABSTRACTAiming to compare three different methods for the determination of organic carbon (OC) in... more ABSTRACTAiming to compare three different methods for the determination of organic carbon (OC) in the soil and fractions of humic substances, seventeen Brazilian soil samples of different classes and textures were evaluated. Amounts of OC in the soil samples and the humic fractions were measured by the dichromate-oxidation method, with and without external heating in a digestion block at 130 °C for 30 min; by the loss-on-ignition method at 450 °C during 5 h and at 600 °C during 6 h; and by the dry combustion method. Dry combustion was used as reference in order to measure the efficiency of the other methods. Soil OC measured by the dichromate-oxidation method with external heating had the highest efficiency and the best results comparing to the reference method. When external heating was not used, the mean recovery efficiency dropped to 71%. The amount of OC was overestimated by the loss-on-ignition methods. Regression equations obtained between total OC contents of the reference me...
Revista Brasileira de Ciência do Solo, 2015
O conhecimento etnopedológico tem fornecido informações importantes sobre o modo de vida das popu... more O conhecimento etnopedológico tem fornecido informações importantes sobre o modo de vida das populações rurais a respeito de suas tradições ancestrais, como a arte de elaborar peças artesanais a partir do barro advindo de solos com características próprias a esse uso. O objetivo deste trabalho foi avaliar física, química e mineralogicamente Planossolos e Gleissolos explorados para a produção de artefatos de cerâmica artesanal em Minas Gerais. Nos barreiros, foram coletados dois perfis de Planossolos (P1 e P2) e um Gleissolo (P3) usados como matéria-prima na produção artesanal de cerâmica. Foram realizadas análises físicas e químicas, limites de liquidez (LL) e plasticidade (LP), índice de plasticidade (IP) e de atividade coloidal (IA), além da mineralogia da fração argila. Os horizontes selecionados pelos ceramistas para a fabricação de cerâmica artesanal (BA, Btg e BCg, do P1; Btg1 e Btg2, do P2; e C2g e C3g, do P3) apresentaram os maiores teores de argila e silte, IP e IA, importa...
The current discussions about environmental problems have required knowledgment new tools and met... more The current discussions about environmental problems have required knowledgment new tools and methodologies to ensure better management of natural ambient. Land cover evaluation has required from environmental monitoring agencies investments in technology that provide accurate and quick results to maximize the opportunities for environmental protection. In this context, the objective of this study was to evaluate new technologies and methodologies for land cover automated detection from satellite images. The study was carried in Araponga/MG (Brazil) county, using the images classification procedures of Maximum Likelihood (MAXVER) method and Artificial Neural Networks (RNA). Associated with the operational simplicity, the MAXVER classification stands out as a proper option for the detection of vegetation cover in environmental studies.
The document suggest methods for determining soil particle size analysis in Brazil, from the expe... more The document suggest methods for determining soil particle size analysis in Brazil, from the experiences and contributions of different researchers in different Brazilian institutions. The objective is to indicate the standardization to be suggested for soil particle size analysis for routines purposes for the most common tropical soils in Brazil.
International Journal of Environmental Studies, 2014
ABSTRACT The paper reports a study of the mobility of Cu, Ni, Zn, Pb and Cd through the profiles ... more ABSTRACT The paper reports a study of the mobility of Cu, Ni, Zn, Pb and Cd through the profiles of tropical soils which received addition of those metals on the surface of soils accommodated in polyvinyl chloride (PVC) columns, separated into seven rings. Leaching tests were conducted by pouring deionized water into soil surface of the top column ring, collecting the leached effluents and analysing the collected extracts for determination of metal concentrations. Soil samples from each column ring were withdrawn and analysed by a sequential extraction method to identify the binding forms of the metals retained in the soil, which correspond to six fractions of metal retained forms in soil. The metal amounts accumulated in leachates varied for each metal and depended on the soil type studied and the horizons where the fraction was located. Compared to the amount of each metal applied to soil surface, only a small proportion reached the rings located at the bottom of the columns. In leachates, only 10% of Cu added to soil surface was found and for the other metals, percentages were even smaller. Texture and organic matter content of soils affected significantly the mobility of heavy metals in the columns. The sequential extraction showed that soluble + exchangeable fraction and organic fraction corresponded to predominant forms of retention of the heavy metals in the soil.
ABSTRACT Due to continued machinery, soil mobilization has caused considerable changes in both so... more ABSTRACT Due to continued machinery, soil mobilization has caused considerable changes in both soil bulk density (physical attributes) and organic C content, risking crop yield reduction and negative environmental effects. In this context, this work aimed at assessing changes in both physical attributes and in organic C content of a Argissolo Vermelho-Amarelo surface horizon, subjected to no-tillage (NT) and conventional tillage with disk plow (DP), heavy harrow (HG), and disc plow plus harrow (DP+HG) for 23 years. A natural forest fragment (NF) was used as reference area. A randomized-block design with 8 x 12 m plots and four replications was used. Soil samples were collected at 0-5, 5-10, 10-20, and 20-40 cm depths in order to assess soil density, total organic carbon content, porosity, saturated hydraulic conductivity, and aggregate stability. Results showed that continued cultivation increases soil physical degradation, as evidenced by both macro porosity and total porosity reduction, aggregate stability, saturated hydraulic conductivity, total organic carbon, and soil density increase. The NT was found to best contribute to soil physical properties improvement and total organic carbon recovery in 0-5 cm surface layer.
To estimate clay dispersion the water dispersible clay is determined in the laboratory. This anal... more To estimate clay dispersion the water dispersible clay is determined in the laboratory. This analysis may not correspond to reality in saline and saline-sodic soils, with high concentrations of salts in the solution. In this context, the dispersed clay was determined, using solutions of different electrical conductivities (0; 0.3; 0.6; 0.9 and 1.2 dS m-1) in seven representative soils of the State of Pernambuco, with the exchangeable-sodium-percentage adjusted in the range of 5-30%. The results showed that there was an increase of dispersed clay directly related to the increase in the exchangeable sodium percentage and the decrease of the electrical conductivity of the solution. The response to treatments was more pronounced in soils with higher proportions of more active clays compared to those with more iron oxides. The determinations of the water dispersible clay are accomplished with deionized or distilled water. However, in soils affected by salts, it is concluded that the determinations should be carried out with solutions of electrical conductivity different from 0 dS m-1 using solutions with values similar to those determined in the saturation extract.
ABSTRACT The evaluation of the impact of use and management on soil compaction is critical in the... more ABSTRACT The evaluation of the impact of use and management on soil compaction is critical in the development of sustainable agricultural systems. The objective of this study was to conduct with two samples of two clayey Oxisols, quantification of the saturated hydraulic conductivity, the macro and the micro porosity in response to compaction index, defined by the relationship between soil bulk density and maximum density determined by Proctor compaction test. The penetration resistance in response to compaction index between -60 and -15,000 hPa was also quantified, and calculated the least limiting water range. The experimental units were artificially compacted soil cores in laboratory, in order to achieve compaction indexes between 0.70 and 1.0. The results showed the importance of this index when comparing characteristics of soil in which the absolute values of bulk density exhibit marked divergence. The compaction index between 0.70 and 0.85 offers no restrictions to plant growth. Higher values indicate restrictions with respect to soil aeration, and when the values exceed 0.95, the penetration resistance impedes root growth.
Revista Brasileira de Ciência do Solo, 2004
A cor é um dos principais atributos considerados na classificação dos solos, indicando a riqueza ... more A cor é um dos principais atributos considerados na classificação dos solos, indicando a riqueza em matéria orgânica e a natureza mineralógica dos óxidos de ferro presentes. Este trabalho teve por objetivo avaliar a capacidade preditiva da cor do solo, determinada pela técnica de refletância difusa, na quantificação dos óxidos de Fe hematita e goethita em diferentes Latossolos brasileiros. Os espectros de refletância separaram os solos mais claros e amarelados dos mais escuros e de coloração vermelha mais intensa, indicando o aumento da refletividade decorrente da redução dos teores dos pigmentos hematita e matéria orgânica. A técnica espectroscópica permitiu a obtenção de valores de matizes mais precisos, com vantagem sobre a Caderneta de Munsell, que fornece dados a intervalos de 2,5 YR. A presença de hematita e goethita nas amostras foi facilmente identificada pela utilização da segunda derivada da função Kubelka-Munk. A similaridade dos espectros desta função, obtida para a terr...
Revista Brasileira de Engenharia Agrícola e Ambiental, 2014
Laboratórios de diferentes regiões do Brasil não utilizam procedimentos uniformes para a execução... more Laboratórios de diferentes regiões do Brasil não utilizam procedimentos uniformes para a execução da análise granulométrica. Soluções de hidróxido de sódio (NaOH) ou de hexametafosfato de sódio e carbonato de sódio [(NaPO3)n + Na2CO3] são as mais utilizadas na dispersão química das partículas do solo. O elevado pH da solução de NaOH favorece a dispersão em solos com minerais de carga variável na fração argila, como os óxidos de ferro e alumínio presentes em solos de regiões tropicais. Com base nesta afirmativa, objetivou-se testar a eficiência de soluções NaOH (D1), [(NaPO3)n + NaOH] (D2) e [(NaPO3)n + Na2CO3] (D3) como dispersantes químicos na análise granulométrica de amostras de dois horizontes de 26 solos de referência do Estado de Pernambuco. A comparação entre os dispersantes foi realizada utilizando-se o teste estatístico L&O. Na comparação de D2 = f(D1) e D3 = f(D1) observou-se que não houve semelhança entre os dispersantes. O intercepto na equação de regressão linear para a...
O presente trabalho teve como objetivo avaliar a presença dos metais pesados Cd, Pb, Cu, Cr, Fe, ... more O presente trabalho teve como objetivo avaliar a presença dos metais pesados Cd, Pb, Cu, Cr, Fe, Mn, Mo, Ni e Zn, em solos agrícolas, água de irrigação e alguns vegetais, provenientes de áreas olerícolas do estado de Minas Gerais. As amostras foram submetidas a digestão ácida e os teores de metais pesados determinados em um espectrofotômetro de emissão de plasma. A maior parte das amostras de solo apresentou baixos teores totais de metais pesados não indicando acumulação desses elementos, à exceção de Cr e Cd, que exibiram teores totais os quais justificam análises complementares; entretanto, para esses elementos, os dados de extração com DTPA foram próximos de zero indicando sua baixa disponibilidade. Nas amostras de água apenas os elementos Cd e Pb não foram identificados. Considerando-se os teores máximos legais permitidos, poucas foram as amostras que superaram os limites. Nas amostras de olerícolas, os teores de Cd, Cr e Ni nem se aproximaram do limite crítico e os teores dos demais elementos ultrapassaram levemente, em sua ampla maioria, o limite considerado. De maneira geral, os dados indicaram que as amostras de solo, água e olerícolas analisadas não estão contaminadas por metais pesados.
Revista Árvore, 2018
The use of trees in integrated crop-livestock-forestry systems (ICLF) allows diversifying product... more The use of trees in integrated crop-livestock-forestry systems (ICLF) allows diversifying production, increasing profitability per area, and providing a higher animal comfort. However, the influence of tree component on soil chemical attributes in this system is still little studied. This study aimed to assess the effect of trees and sun-exposed faces to solar radiation on soil nutrient availability at different distances of tree rows in an integrated crop-livestock-forestry system. This study was carried out in the northern Mato Grosso State, Brazil, in the Cerrado - Amazon Forest transition region in an ICLF with the tree component formed by three eucalyptus rows. The assessment carried out in the second year of ICLF implantation considered the effect of tree distances (3, 6, 10, and 15 m) on two sun-exposed faces to solar radiation (north and south) on the main soil chemical attributes. Soil sampling was performed at depths of 0-0.05, 0.05-0.10, 0.10-0.20, and 0.20-0.30 m. The re...
Revista Árvore, 2018
Integrated crop-livestock-forest (iCLF) systems have gained prominence in the past decades as an ... more Integrated crop-livestock-forest (iCLF) systems have gained prominence in the past decades as an alternative of sustainable land use, particularly in regions in which there is pressure against agricultural expansion in protected ecosystems such as the Brazilian Amazon. In this context, the objective of this study is to evaluate the effects of one year of use of the iCLF system in the Cerrado/Amazon transition region to determine its impact on soil quality compared to other traditional land uses in the region (planted forest, crop, forage, and native forest). The results indicated that the iCLF system did not jeopardize the soil physical quality, and only the crop land use affected the soil physical attributes. The land uses with the lowest impact on the physical condition of the soil were the iCLF system and the planted forest.
The Science of the total environment, Jan 16, 2017
The objective of this study was to evaluate sediment, water and nutrient losses from different pa... more The objective of this study was to evaluate sediment, water and nutrient losses from different pasture managements in the Atlantic Rainforest biome. A field study was carried out in Alegre Espiríto Santo, Brazil, on a Xanthic Ferralsol cultivated with braquiaria (Brachiaria brizantha). The six pasture managements studied were: control (CON), chisel (CHI), fertilizer (FER), burned (BUR), plowing and harrowing (PH), and integrated crop-livestock (iCL). Runoff and sediment samples were collected and analyzed for calcium (Ca), magnesium (Mg), potassium (K), phosphorus (P) and organic carbon contents. Soil physical attributes and above and below biomass were also evaluated. The results indicated that higher water loss was observed for iCL (129.90mm) and CON (123.25mm) managements, and the sediment losses were higher for CON (10.24tha(-1)) and BUR (5.20tha(-1)) managements when compared to the other managements. Majority of the nutrients losses occurred in dissolved fraction (99% of Ca, 9...
CATENA, 2017
Knowledge on active-layer dynamics and permafrost distribution is of especial importance in Marit... more Knowledge on active-layer dynamics and permafrost distribution is of especial importance in Maritime Antarctica, where dramatic climate warming occurred in the last decades. Few long-term studies of active-layer temperatures in this region, and no one focus on recently deglaciated areas under paraglacial conditions. This paper analyses the long-term soil thermal regime of a warm-based glacial front site located at Low Head, King George Island. The monitoring system consists of soil temperature probes connected to a datalogger that recorded data at hourly intervals. We calculated the thawing days (TD), freezing days (FD), number of isothermal days (ID), number of freeze-thaw days (FTD), thawing degree days (TDD), freezing degree days (FDD), and the apparent thermal diffusivity (ATD). The results indicate that active layer thermal regime at Low Head is similar to other periglacial environments from Maritime Antarctica, with differences associated with the influence from the nearby warm-based glacier. Surface temperatures show greater variations during the summer resulting in frequent freeze and thaw cycles, mainly (1 cm and 10 cm). The temperature profile during the studied period indicates that the active layer thickness reached a maximum of 106 cm on February 7th 2015. Soil temperature buffering was limited by the low snow cover, low soil moisture, and absence of vegetation. Based on the high interannual variability detected during the five years monitoring run, we stress that longer monitoring periods are necessary for a more detailed knowledge on how permafrost respond to climate changes in this rapidly warming zone.
Revista da Faculdade de Odontologia - UPF, Jul 17, 2012
Cirurgiã-dentista, aluna do curso de mestrado em Biologia Oral e do curso de especialização em Od... more Cirurgiã-dentista, aluna do curso de mestrado em Biologia Oral e do curso de especialização em Odontologia Legal, Faculdade de Odontologia de Ribeirão Preto (USP). ** Cirurgião-dentista, aluno do curso de mestrado em Biologia Oral, Faculdade de Odontologia de Ribeirão Preto (USP).
Revista Ceres, 2015
ABSTRACTAiming to compare three different methods for the determination of organic carbon (OC) in... more ABSTRACTAiming to compare three different methods for the determination of organic carbon (OC) in the soil and fractions of humic substances, seventeen Brazilian soil samples of different classes and textures were evaluated. Amounts of OC in the soil samples and the humic fractions were measured by the dichromate-oxidation method, with and without external heating in a digestion block at 130 °C for 30 min; by the loss-on-ignition method at 450 °C during 5 h and at 600 °C during 6 h; and by the dry combustion method. Dry combustion was used as reference in order to measure the efficiency of the other methods. Soil OC measured by the dichromate-oxidation method with external heating had the highest efficiency and the best results comparing to the reference method. When external heating was not used, the mean recovery efficiency dropped to 71%. The amount of OC was overestimated by the loss-on-ignition methods. Regression equations obtained between total OC contents of the reference me...
Revista Brasileira de Ciência do Solo, 2015
O conhecimento etnopedológico tem fornecido informações importantes sobre o modo de vida das popu... more O conhecimento etnopedológico tem fornecido informações importantes sobre o modo de vida das populações rurais a respeito de suas tradições ancestrais, como a arte de elaborar peças artesanais a partir do barro advindo de solos com características próprias a esse uso. O objetivo deste trabalho foi avaliar física, química e mineralogicamente Planossolos e Gleissolos explorados para a produção de artefatos de cerâmica artesanal em Minas Gerais. Nos barreiros, foram coletados dois perfis de Planossolos (P1 e P2) e um Gleissolo (P3) usados como matéria-prima na produção artesanal de cerâmica. Foram realizadas análises físicas e químicas, limites de liquidez (LL) e plasticidade (LP), índice de plasticidade (IP) e de atividade coloidal (IA), além da mineralogia da fração argila. Os horizontes selecionados pelos ceramistas para a fabricação de cerâmica artesanal (BA, Btg e BCg, do P1; Btg1 e Btg2, do P2; e C2g e C3g, do P3) apresentaram os maiores teores de argila e silte, IP e IA, importa...
The current discussions about environmental problems have required knowledgment new tools and met... more The current discussions about environmental problems have required knowledgment new tools and methodologies to ensure better management of natural ambient. Land cover evaluation has required from environmental monitoring agencies investments in technology that provide accurate and quick results to maximize the opportunities for environmental protection. In this context, the objective of this study was to evaluate new technologies and methodologies for land cover automated detection from satellite images. The study was carried in Araponga/MG (Brazil) county, using the images classification procedures of Maximum Likelihood (MAXVER) method and Artificial Neural Networks (RNA). Associated with the operational simplicity, the MAXVER classification stands out as a proper option for the detection of vegetation cover in environmental studies.
The document suggest methods for determining soil particle size analysis in Brazil, from the expe... more The document suggest methods for determining soil particle size analysis in Brazil, from the experiences and contributions of different researchers in different Brazilian institutions. The objective is to indicate the standardization to be suggested for soil particle size analysis for routines purposes for the most common tropical soils in Brazil.
International Journal of Environmental Studies, 2014
ABSTRACT The paper reports a study of the mobility of Cu, Ni, Zn, Pb and Cd through the profiles ... more ABSTRACT The paper reports a study of the mobility of Cu, Ni, Zn, Pb and Cd through the profiles of tropical soils which received addition of those metals on the surface of soils accommodated in polyvinyl chloride (PVC) columns, separated into seven rings. Leaching tests were conducted by pouring deionized water into soil surface of the top column ring, collecting the leached effluents and analysing the collected extracts for determination of metal concentrations. Soil samples from each column ring were withdrawn and analysed by a sequential extraction method to identify the binding forms of the metals retained in the soil, which correspond to six fractions of metal retained forms in soil. The metal amounts accumulated in leachates varied for each metal and depended on the soil type studied and the horizons where the fraction was located. Compared to the amount of each metal applied to soil surface, only a small proportion reached the rings located at the bottom of the columns. In leachates, only 10% of Cu added to soil surface was found and for the other metals, percentages were even smaller. Texture and organic matter content of soils affected significantly the mobility of heavy metals in the columns. The sequential extraction showed that soluble + exchangeable fraction and organic fraction corresponded to predominant forms of retention of the heavy metals in the soil.
ABSTRACT Due to continued machinery, soil mobilization has caused considerable changes in both so... more ABSTRACT Due to continued machinery, soil mobilization has caused considerable changes in both soil bulk density (physical attributes) and organic C content, risking crop yield reduction and negative environmental effects. In this context, this work aimed at assessing changes in both physical attributes and in organic C content of a Argissolo Vermelho-Amarelo surface horizon, subjected to no-tillage (NT) and conventional tillage with disk plow (DP), heavy harrow (HG), and disc plow plus harrow (DP+HG) for 23 years. A natural forest fragment (NF) was used as reference area. A randomized-block design with 8 x 12 m plots and four replications was used. Soil samples were collected at 0-5, 5-10, 10-20, and 20-40 cm depths in order to assess soil density, total organic carbon content, porosity, saturated hydraulic conductivity, and aggregate stability. Results showed that continued cultivation increases soil physical degradation, as evidenced by both macro porosity and total porosity reduction, aggregate stability, saturated hydraulic conductivity, total organic carbon, and soil density increase. The NT was found to best contribute to soil physical properties improvement and total organic carbon recovery in 0-5 cm surface layer.
To estimate clay dispersion the water dispersible clay is determined in the laboratory. This anal... more To estimate clay dispersion the water dispersible clay is determined in the laboratory. This analysis may not correspond to reality in saline and saline-sodic soils, with high concentrations of salts in the solution. In this context, the dispersed clay was determined, using solutions of different electrical conductivities (0; 0.3; 0.6; 0.9 and 1.2 dS m-1) in seven representative soils of the State of Pernambuco, with the exchangeable-sodium-percentage adjusted in the range of 5-30%. The results showed that there was an increase of dispersed clay directly related to the increase in the exchangeable sodium percentage and the decrease of the electrical conductivity of the solution. The response to treatments was more pronounced in soils with higher proportions of more active clays compared to those with more iron oxides. The determinations of the water dispersible clay are accomplished with deionized or distilled water. However, in soils affected by salts, it is concluded that the determinations should be carried out with solutions of electrical conductivity different from 0 dS m-1 using solutions with values similar to those determined in the saturation extract.
ABSTRACT The evaluation of the impact of use and management on soil compaction is critical in the... more ABSTRACT The evaluation of the impact of use and management on soil compaction is critical in the development of sustainable agricultural systems. The objective of this study was to conduct with two samples of two clayey Oxisols, quantification of the saturated hydraulic conductivity, the macro and the micro porosity in response to compaction index, defined by the relationship between soil bulk density and maximum density determined by Proctor compaction test. The penetration resistance in response to compaction index between -60 and -15,000 hPa was also quantified, and calculated the least limiting water range. The experimental units were artificially compacted soil cores in laboratory, in order to achieve compaction indexes between 0.70 and 1.0. The results showed the importance of this index when comparing characteristics of soil in which the absolute values of bulk density exhibit marked divergence. The compaction index between 0.70 and 0.85 offers no restrictions to plant growth. Higher values indicate restrictions with respect to soil aeration, and when the values exceed 0.95, the penetration resistance impedes root growth.
Revista Brasileira de Ciência do Solo, 2004
A cor é um dos principais atributos considerados na classificação dos solos, indicando a riqueza ... more A cor é um dos principais atributos considerados na classificação dos solos, indicando a riqueza em matéria orgânica e a natureza mineralógica dos óxidos de ferro presentes. Este trabalho teve por objetivo avaliar a capacidade preditiva da cor do solo, determinada pela técnica de refletância difusa, na quantificação dos óxidos de Fe hematita e goethita em diferentes Latossolos brasileiros. Os espectros de refletância separaram os solos mais claros e amarelados dos mais escuros e de coloração vermelha mais intensa, indicando o aumento da refletividade decorrente da redução dos teores dos pigmentos hematita e matéria orgânica. A técnica espectroscópica permitiu a obtenção de valores de matizes mais precisos, com vantagem sobre a Caderneta de Munsell, que fornece dados a intervalos de 2,5 YR. A presença de hematita e goethita nas amostras foi facilmente identificada pela utilização da segunda derivada da função Kubelka-Munk. A similaridade dos espectros desta função, obtida para a terr...
Revista Brasileira de Engenharia Agrícola e Ambiental, 2014
Laboratórios de diferentes regiões do Brasil não utilizam procedimentos uniformes para a execução... more Laboratórios de diferentes regiões do Brasil não utilizam procedimentos uniformes para a execução da análise granulométrica. Soluções de hidróxido de sódio (NaOH) ou de hexametafosfato de sódio e carbonato de sódio [(NaPO3)n + Na2CO3] são as mais utilizadas na dispersão química das partículas do solo. O elevado pH da solução de NaOH favorece a dispersão em solos com minerais de carga variável na fração argila, como os óxidos de ferro e alumínio presentes em solos de regiões tropicais. Com base nesta afirmativa, objetivou-se testar a eficiência de soluções NaOH (D1), [(NaPO3)n + NaOH] (D2) e [(NaPO3)n + Na2CO3] (D3) como dispersantes químicos na análise granulométrica de amostras de dois horizontes de 26 solos de referência do Estado de Pernambuco. A comparação entre os dispersantes foi realizada utilizando-se o teste estatístico L&O. Na comparação de D2 = f(D1) e D3 = f(D1) observou-se que não houve semelhança entre os dispersantes. O intercepto na equação de regressão linear para a...
O presente trabalho teve como objetivo avaliar a presença dos metais pesados Cd, Pb, Cu, Cr, Fe, ... more O presente trabalho teve como objetivo avaliar a presença dos metais pesados Cd, Pb, Cu, Cr, Fe, Mn, Mo, Ni e Zn, em solos agrícolas, água de irrigação e alguns vegetais, provenientes de áreas olerícolas do estado de Minas Gerais. As amostras foram submetidas a digestão ácida e os teores de metais pesados determinados em um espectrofotômetro de emissão de plasma. A maior parte das amostras de solo apresentou baixos teores totais de metais pesados não indicando acumulação desses elementos, à exceção de Cr e Cd, que exibiram teores totais os quais justificam análises complementares; entretanto, para esses elementos, os dados de extração com DTPA foram próximos de zero indicando sua baixa disponibilidade. Nas amostras de água apenas os elementos Cd e Pb não foram identificados. Considerando-se os teores máximos legais permitidos, poucas foram as amostras que superaram os limites. Nas amostras de olerícolas, os teores de Cd, Cr e Ni nem se aproximaram do limite crítico e os teores dos demais elementos ultrapassaram levemente, em sua ampla maioria, o limite considerado. De maneira geral, os dados indicaram que as amostras de solo, água e olerícolas analisadas não estão contaminadas por metais pesados.