Navegando por Autor "Pereira, Marcos Gervasio"

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Amazonian Dark Earths in Rondônia State: Soil properties, carbon dating and classification
(Revista Brasileira de Ciência do Solo, 2021-03-02) Cavassani, Rafael de Souza; Anjos, Lúcia Helena Cunha dos; Pereira, Marcos Gervasio; Garcia, Andrés Calderin
Throughout the Amazon region, dark-colored soils with increased fertility are identified and referred as Amazonian Dark Earths (ADE). These unique soils are characterized by an anthropic surface horizon with dark colors, presence of charcoal and artifacts, in contrast with surrounding non-ADE soils. The ADEs show extraordinary properties such as the capacity of maintaining the dark colors and high nutrient levels after years of farming, even under the highly favorable climatic conditions for oxidation of organic matter and weathering of nutrients of Amazon region. The ADE are considered islands of fertility in the Amazon biome, as well as very important models for research, in terms of agricultural and environmental sustainability, carbon sequestration, nutrient bioavailability, food security, and for anthropological studies. However, there are many unanswered questions regarding the extent of human alterations, how they were formed, and their classification in the taxonomic systems. Therefore, the objectives of this study were to identify, describe, and characterize soil profiles of ADEs, located in the Southern region of Rondônia State, Brazil, and to contribute to their classification according to the Brazilian Soil Classification System (SiBCS) and the World Reference Base (WRB). Five soil profiles were described and sampled; P1 to P3 were under grass pastures, P4 and P5 under forest and crops with no-till, respectively. The morphological, physical, and chemical attributes, as well as contents of Fe, Al, Si, and Ti oxides and extractable iron forms were characterized. The anthropic horizons exhibited dark colors, artifacts, charcoal, sandier textures, predominantly granular structures, abrupt or clear transitions, and mostly wavy and irregular boundaries. Values of pH, Ca 2+ , Mg 2+ , exchangeable bases (S), CEC, and C were high in all anthropic horizons. Compared to non-ADE soils in the Amazon region, phosphorus contents were superior in all anthropic horizons, with the highest values in surface horizons of P1, P2, and P3. According to SiBCS, P1 was classified as Cambissolo, P2 as Argissolo, and P3, P4, and P5 as Latossolos. Except for P4, where values of extractable P by Mehlich-1 are lower than 30 mg kg -1 , all soils fulfilled the requirements for the anthropic horizon in the SiBCS, and new classes at the subgroup level were proposed. In the WRB, P4 and P5 were classified as Ferralsols. The other profiles were classified as Anthrosols. The radiocarbon dates (C 14 ) of charcoal fragments, obtained using a mass accelerator, showed ages between 940 ± 40 and 1230 ± 60 years BP.
Aporte e decomposição da serapilheira e produção de biomassa radicular em florestas com diferentes estágios sucessionais em Pinheiral, RJ
(Ciência Florestal, 2010-07) Paula, Ranieri Ribeiro; Menezes, Carlos Eduardo Gabriel; Pereira, Marcos Gervasio; Correia, Maria Elizabeth Fernandes; Anjos, Lúcia Helena Cunha dos; Souza, Manuel Euzébio de
Este estudo objetivou avaliar a deposição e decomposição da serapilheira e a produção de biomassa radicular de três fragmentos florestais em diferentes estágios sucessionais (avançado, médio e inicial) localizados no município de Pinheiral, RJ. Para interceptação da serapilheira instalaram-se em cada fragmento, dez coletores cônicos. Avaliou-se a biomassa radicular em dois períodos (chuvoso e seco), amostrando-se pelo método do monólito, em 0-10, 10-20 e 20-30 cm e dez repetições por profundidade. Não ocorreram diferenças na deposição de serapilheira entre as áreas, mas apenas uma tendência de aumento com a evolução sucessional. Não foram verificadas variações temporais de serapilheira entre as áreas mais jovens, inicial e médio no decorrer do ano, com tendência de aumento nos meses de julho e agosto. Em estágio avançado, o aporte da serapilheira pôde ser agrupado em dois períodos: “fevereiro a julho”, menores valores e “agosto a janeiro”, maiores valores. A deposição das frações folhas e material reprodutivo diminuíram, enquanto ramos e outros aumentaram com o avançar sucessional. A decomposição da serapilheira mostrou em estágio sucessional médio a menor constante k (0,0038 g.g-1.dia-1) e maior tempo de meia vida (182 dias), seguida por inicial (0,044 g.g-1.dia-1 e 154 dias) e avançado (0,0064 g.g-1.dia-1 e 108 dias). A biomassa radicular nas diferentes áreas e profundidades, no período seco e chuvoso, apresentou maiores valores em estágio avançado, intermediários em médio e menores em inicial. As diferenças sazonais da biomassa radicular ocorreram sobretudo em estágio médio, com maiores valores na coleta de junho.
Application of georadar in areas with different vegetation cover
(Floresta e Ambiente, 2017) Francelino, Márcio Rocha; Coutinho, Fernando Silva; Pereira, Marcos Gervasio; Tostes, Juliana de Oliveira; Gaia-Gomes, João Henrique
The Atlantic Forest degradation and fragmentation imposes the need for soil and vegetation assessments in order to estimate the environmental vulnerability of the remnants. The objective of this study was to evaluate the georadar applications in areas of Atlantic Forest under different forms of use in Pinheiral, State of Rio de Janeiro, Brazil, through penetrometer impact and ground penetrating radar (GPR). Forest fragments at different stages of regeneration, and pasture and agriculture (perennial and annual) areas were selected for study. Soil characterization was performed through measurements of soil resistance to penetration (SRP) with an impact penetrometer, and the soil properties with a ground penetrating radar (georadar). SRP increased in the forest areas at initial, medium and advanced stages from 2.0 to 2.5, 2.0 to 3.0 and 2.5 to 6.0 MPa, respectively. In the perennial and annual agriculture areas, the increase in SRP was due to differences in their mineral composition, and the lowest values found in the annual agriculture area were due to fauna activity. The employment of GPR generated information in a more rapid manner than with the use of impact penetrometer.
Biogenic and physicogenic aggregates: formation pathways, assessment techniques, and influence on soil properties
(Sociedade Brasileira de Ciência do Solo, 2021-10-13) Pereira, Marcos Gervasio; Loss, Arcangelo; Batista, Itaynara; Melo, Thadeu Rodrigues de; Neto, Eduardo Carvalho da Silva; Pinto, Luiz Alberto da Silva Rodrigues
The soil particles can be gathered through physical and/or chemical processes in association with the biological activity, leading to the formation of aggregates. Soil aggregates has several functions in the soil, increasing macroporosity and water circulation - consequently reducing soil erosion and mechanical resistance to root growth, contributing to greater fixation of plants to the soil and absorption of water and nutrients, and protection of intra-aggregate organic matter. The aggregates were initially classified morphologically and in terms of their stability. In recent years, another way of evaluating aggregates, regarding their formation or origin pathway, has gained prominence in the studies conducted in Brazil. As for their origin, the aggregates can be classified morphologically as physicogenic, biogenic, or intermediate. This manuscript presents the techniques used to sample aggregates, the morphological patterns for their distinction observed in different soil classes and management types, and the chemical and physical properties. Additionally, we present analyses that are not commonly used to evaluate aggregates but which have the potential to be used as tools for a better understanding of their origin and to evaluate their modifications when subject to different types of management. In practical terms, identifying the aggregate origin and determining the related attributes allows recognizing the effect of vegetation/soil/management on soil aggregate forming agents, mainly roots and soil fauna, which reflects soil quality. For future studies, and especially to determine the importance of biogenic aggregation in improving edaphic properties, we suggest the use of micromorphology, near-infrared spectroscopy, X-ray computed tomography, clay dispersion analyses in addition with chemical, physical, and biological analysis. This approach can contribute to the identification of other patterns related to pedogenesis and the pathways of aggregate formation.
Digital soil mapping of soil properties in the “Mar de Morros” environment using spectral data
(Revista Brasileira de Ciência do Solo, 2018) Fernandes Filho, Elpídio Inácio; Campbell, Patrícia Morais da Matta; Francelino, Márcio Rocha; Demattê, José Alexandre Melo; Pereira, Marcos Gervasio; Guimarães, Clécia Cristina Barbosa; Pinto, Luiz Alberto da Silva Rodrigues
Quantification of soil properties is essential for better understanding of the environment and better soil management. The conventional techniques of laboratory analysis are sometimes costly and detrimental to the environment. Thus, development of new techniques for soil analysis that do not generate residues, such as spectroscopy, is increasingly necessary as a viable way to estimate a wide range of soil properties. The objective of this study was to predict the levels of organic carbon (OC), clay, and extractable phosphorus (P), from the spectral responses of soil samples in the visible and near infrared (Vis-NIR), medium infrared (MIR), and Vis-NIR-MIR using different preprocessing methods combined with five prediction models. Soil samples were collected in Iconha, Espírito Santo State, Brazil, in the Ribeirão Inhaúma basin. A total of 184 samples were collected from 92 sites at two depths (0.00-0.10 and 0.10-0.30 m). Physical, chemical, and spectral analyses were performed according to routine soil laboratory methods. Random selection was made of 70 % of total samples for training and 30 % for validation of the models. The coefficient of determination (R2) and root mean square error (RMSE) were calculated in order to assess model performance. The standardized indexes of prediction error RPD and RPIQ were also calculated. For clay and OC, the best R2 was found in the MIR spectrum, at 0.69 and 0.65, respectively, and for P, it was 0.57 in Vis-NIR. The MSC (Multiplicative Scatter Correction), CR (Continuum removal), and SNV (Standard Normal Variate) preprocesses were most efficient for predicting clay, OC, and P, respectively, while the PLSR - Partial Least Squares Regression (OC and P) and SVM - Support Vector Machine (clay) gave the best predictions and are therefore recommended for modeling these properties in the study area. The models identified in this study can be used to discriminate soils according to a critical test value for clay, OC, and P.
Edaphic fauna and soil properties under different managements in areas impacted by natural disaster in a mountainous region
(Revista Brasileira de Ciência do Solo, 2021-03-19) Lima, Sandra Santana de; Aquino, Adriana Maria de; Silva, Rafaela Martins da; Matos, Priscila Silva; Pereira, Marcos Gervasio
Soil invertebrate fauna plays a major role in several environmental processes, and its absence can negatively impact ecosystem health. This study aimed to assess the recovery of epigeal and edaphic invertebrate faunal communities following an environmental disaster, with landslides, mudflow, and river floods, in sites under different management systems, the effects of cover crops on invertebrate fauna, and their relationship with soil physical and chemical properties in the mountainous region of Rio de Janeiro State, Brazil. The following sites were evaluated: CF, a site under conventional farming without any record of natural hazard events; LS, a site impacted by an intense landslide event that left the area buried by mudflow; RO1, a site affected by river overflow and treated with NPK fertilizer and poultry litter; RO2, a site affected by river overflow and subjected to liming and heavy fertilization with NPK; and RO3, a site affected by a less intense river overflow and subjected to fertilization with poultry litter and NPK fertilizer. At each site, epigeal and edaphic fauna were sampled using pitfall traps and a monolith sampler, respectively. Physical (soil temperature, moisture, aggregate stability, and density) and chemical (pH in water, Ca 2+ , Mg 2+ , Al 3+ , K + , P, cation-exchange capacity, and total organic carbon) properties were determined in the 0.00-0.05 and 0.00-0.10 m layers. The predominant epigeal faunal groups were Entomobryomorpha, Poduromorpha, Diptera, and Coleoptera; and the predominant edaphic faunal groups, Coleoptera and Oligochaeta. There was a positive correlation between Coleoptera larvae, Hymenoptera, and species richness with total organic carbon. Coleoptera larvae were positively associated with biogenic aggregate stability, whereas Coleoptera was positively associated with physicogenic aggregate stability. Oligochaeta showed a positive correlation with soil moisture. Cover crops favored the development of epigeal and edaphic faunal groups that enhance soil properties through organic matter fragmentation and decomposition, and structural engineering. The strong correlation between soil chemical, physical, and biological properties demonstrate the importance of monitoring these components to assess the recovery of disaster-affected areas.
Environmental correlation and spatial autocorrelation of soil properties in Keller Peninsula, Maritime Antarctica
(Revista Brasileira de Ciência do Solo, 2018-01-08) Moraes, André Geraldo de Lima; Francelino, Marcio Rocha; Carvalho Junior, Waldir de; Pereira, Marcos Gervasio; Thomazini, André; Schaefer, Carlos Ernesto Gonçalves Reynaud
The pattern of variation in soil and landform properties in relation to environmental covariates are closely related to soil type distribution. The aim of this study was to apply digital soil mapping techniques to analysis of the pattern of soil property variation in relation to environmental covariates under periglacial conditions at Keller Peninsula, Maritime Antarctica. We considered the hypothesis that covariates normally used for environmental correlation elsewhere can be adequately employed in periglacial areas in Maritime Antarctica. For that purpose, 138 soil samples from 47 soil sites were collected for analysis of soil chemical and physical properties. We tested the correlation between soil properties (clay, potassium, sand, organic carbon, and pH) and environmental covariates. The environmental covariates selected were correlated with soil properties according to the terrain attributes of the digital elevation model (DEM). The models evaluated were linear regression, ordinary kriging, and regression kriging. The best performance was obtained using normalized height as a covariate, with an R2 of 0.59 for sand. In contrast, the lowest R2 of 0.15 was obtained for organic carbon, also using the regression kriging method. Overall, results indicate that, despite the predominant periglacial conditions, the environmental covariates normally used for digital terrain mapping of soil properties worldwide can be successfully employed for understanding the main variations in soil properties and soil-forming factors in this region.
Impact of land use on Histosols properties in urban agriculture ecosystems of Rio de Janeiro, Brazil
(Sociedade Brasileira de Ciência do Solo, 2020-06-03) Santos, Otavio Augusto Queiroz dos; Neto, Eduardo Carvalho da Silva; García, Andrés Calderín; Fagundes, Hugo de Souza; Diniz, Yan Vidal de Figueiredo Gomes; Ferreira, Robert; Pereira, Marcos Gervasio
Histosols provide several ecosystem services, related mainly to their reserves of carbon and nitrogen. Management practices in these soils can increase the mineralization of organic matter and contribute to the emission of greenhouse gases. This study aimed to investigate the effect of tillage with plowing and drainage on Histosol properties in three land use systems located in the municipality of Rio de Janeiro, Brazil. Three areas subjected to different land use systems over the last twenty years were chosen: Area 1, secondary forest with natural regeneration; Area 2, conventional tillage of cassava with plowing; and Area 3, intercropped coconut + cassava with an artificial drainage system. The chemical characterization, von Post scale of organic matter decomposition, percentage of rubbed fiber, organic matter, percentage of mineral material, bulk density, electrical conductivity, soluble phosphate, total organic carbon (TOC) and nitrogen (NT), organic carbon fractions, and C and N stocks were analyzed. Our results showed the critical, nearly irreversible effects of agricultural practices comprising drainage and plowing of the soil. Over twenty years, in Area 2, the TOC and NT values decreased by 33 and 20 %, respectively in the histic horizon, and by about 17 and 8 %, respectively in the gley horizon. In Area 3, the TOC and NT values decreased by 31 and 18 %, respectively, in the histic horizon, and by 27 and 21 % in the gley horizon. Our findings also showed that the loss of C is related to the labile organic carbon, which is more sensitive to environmental changes, even at deeper depths. The plowing of the soil decreases the organic matter content due to the accelerated oxidation of organic matter, increasing the bulk density. Drainage, besides the loss of organic matter by subsidence, promotes the sulfidization of the soil with a high content of SO4 2-, due to the oxidation of soil materials containing sulfides.
Physicogenic and biogenic aggregates under different management systems in the Cerrado region, Brazil
(Sociedade Brasileira de Ciência do Solo, 2021-01-28) Pinto, Luiz Alberto da Silva Rodrigues; Torres, José Luiz Rodrigues; Morais, Igor de Sousa; Ferreira, Robert; Júnior, Wanderson Farias da Silva; Lima, Sandra de Santana; Beutler, Sidinei Júlio; Pereira, Marcos Gervasio
An important strategy for the sustainable management of Cerrado soils is no-till (NT) systems, which may improve soil properties, particularly aggregation. Soil aggregates can be categorized according to their formation pathways into physicogenic (Phy) and biogenic (Bio). This study aimed (i) to quantify the relative proportion of physicogenic and biogenic aggregates and (ii) evaluate the levels of total organic carbon and their respective humic and physical fractions in the aggregates’ formation pathways. The following managed and unmanaged sites were evaluated: a 6-year no-till site (6NT), an 18-year no-till site (18NT), a conventional tillage site (CT), and a reference Cerrado site (RS). Retained aggregates were analyzed morphologically, separated into Phy and Bio, and quantified. Subsequently, aggregates were subjected to total organic carbon (TOC) determination, fulvic acid carbon, humic acid carbon, humin carbon, particulate organic carbon (POC), mineral-associated organic carbon, and free light fraction carbon (FLFC). The proportion of Bio aggregates increased with decreasing management intensity. When TOC and humic acid carbon levels were compared between sites, it was found that Bio aggregates from 18NT and 6NT contained higher carbon content than Bio aggregates from CT. Particulate organic carbon and FLFC differed between aggregate types, with higher POC values observed in Bio aggregates from CT and 18NT and higher FLFC values in Bio aggregates from CT, 6NT, and 18NT. The practices adopted in the conservation management system favored biogenic aggregation in the Cerrado region, which can be proven through the study of the fractions of soil organic matter contained in these aggregates. The biogenic aggregation changed the SOM dynamics. Principal component analysis showed a clear distinction between conventional and conservationist management systems.
Produção de matéria seca, crescimento radicular e absorção de cálcio, fósforo e alumínio por coffea canephora e coffea arabica sob influência da atividade do alumínio em solução
(Revista Brasileira de Ciência do Solo, 2007-10) Mattiello, Edson Marcio; Pereira, Marcos Gervasio; Zonta, Everaldo; Mauri, Jocimar; Matiello, José Dioenis; Meireles, Paulo Geovane; Silva, Ivo Ribeiro da
Este trabalho teve como objetivo avaliar a produção de matéria seca, o crescimento radicular e a absorção e distribuição do Ca, P e Al nas folhas, no caule e nas raízes de dois clones de café conilon (Coffea canephora) (Mtl 25 e Mtl 27) e de uma variedade de café Catuaí Amarelo (Coffea arabica), cultivados em solução nutritiva com atividade crescente de Al^3+. As plantas foram cultivadas em vasos com capacidade para 5 L, contendo solução nutritiva de Hoagland & Arnon, modificada. Após oito dias de adaptação, as plantas foram submetidas a concentrações de Al de 0, 500, 1.000 e 2.000 µmol L^-1, que corresponderam a atividades de Al^3+ em solução, estimadas pelo software GEOCHEM, de 20,68, 50,59, 132,9 e 330,4 µmol L^-1, respectivamente. Foram determinados os teores de Ca, Al e P na planta. O sistema radicular foi separado, para determinação da área e do comprimento. A variedade Catuaí Amarelo (Coffea arabica) apresentou-se menos sensível ao Al^3+, quando comparada aos clones de conilon (Coffea canephora). O clone de conilon Mtl 25 foi menos sensível ao Al^3+ em relação ao Mtl 27. O aumento da atividade de Al^3+ promoveu redução nos teores de P e Ca nas folhas e raízes do cafeeiro, especialmente nos clones Mtl 25 e Mtl 27. O acúmulo de Al no sistema radicular e a restrição do transporte para a parte aérea são importantes fatores na tolerância de plantas ao Al^3+.
Relação solo/vegetação em ambiente de cerrado sobre influência do grupo Urucuia
(Ciência Florestal, 2015-04) Francelino, Márcio Rocha; Silva, Renata Botelho Machado da; Moura, Pedro Adnet; Moura, Tom Adnet; Pereira, Marcos Gervasio; Oliveira, Camila Paula de
A vegetação de Cerrado brasileiro compreende um mosaico natural de fisionomias, de campos abertos a savanas e florestas. Acredita-se que a presença de diferentes fitofisionomias em uma região pode ser explicada em parte pela relação direta com os atributos do solo presentes na mesma. O presente trabalho objetivou estudar a relação entre solo e vegetação em uma área do Bioma Cerrado sobre influência do Grupo Urucuia. Para tanto, foi realizado um levantamento de solos e vegetação na escala 1:50.000 em uma área de aproximadamente 32 mil hectares localizada na região da tríplice divisa entre Minas Gerais, Goiás e Bahia, tendo como substrato o arenito do Grupo Urucuia. Os resultados analíticos das classes de solos foram relacionados com os dados das fitofisionomias presentes através de análise estatística comum e pela determinação dos componentes principais. Os solos da região refletiram bem o material de origem, apresentando elevados teores de areia, com predomínio de Latossolo Vermelho Amarelo distrófico típico e Latossolo Amarelo Distrófico psamítico, presentes em mais de 35% de toda a área de estudo. A fitofisionomia mais comum foi o Cerrado sentido restrito típico. A análise dos componentes principais indicou que a areia fina, a argila e o alumínio responderam por 93,7% da variabilidade da relação entre solos e as fitofisionomia.
Soil classes and properties explain the occurrence and fruit production of Brazil nut
(Revista Brasileira de Ciência do Solo, 2021-05-12) Silva, Camila Santos da; Silva, Lucielio Manoel da; Wadt, Lucia Helena de Oliveira; Miqueloni, Daniela Popim; Silva, Katia Emidio da; Pereira, Marcos Gervasio
Soil properties and classes can influence the occurrence of plants and the production of Brazil nut fruits and may have a different distribution between sites. This study aimed to evaluate the relationship of plants’ occurrence, production of Brazil nut fruits, and spatial variability of the properties in different soil classes in two Brazil nut stand in the state of Acre, Brazil. The study was conducted in two plots in two native Brazil nut stand, Cachoeira (CP01 and CP02 - plots 1 and 2) and Filipinas (FP01 and FP02 - plots 1 and 2). The soil profiles were described morphologically. Sixty soil samples were collected in each plot. The chemical properties, granulometry, soil density, particle density, and estimated total porosity were determined. The average fruit production was calculated by counting the fruits in a sample of Brazil nut trees. Subsequently, the trees were divided into three classes of production: low (≤1.5 can; the can unit has 18-L, which is able to hold 59 and 77 fruits, respectively, for Cachoeira and Filipinas), medium (1.6 to 3.9 cans), and high (≥4.0 cans). The can unit is the traditional measure of volume in the region and varies according to the locality. Cluster analysis was performed to determine whether there was a difference between Brazil nut stands and soil profiles, and geostatistics was used to evaluate the spatial dependence of soil properties. The highest occurrence of Brazil nut trees with high fruit production (≥4.0 cans) was found in the Latossolo Vermelho Distrófico argissólico (Oxisol) and Argissolo Vermelho-Amarelo Distrófico típico (Ultisol). However, the Argisol also hosted the plants with the lowest productions (≤1.5 can). The pH, total organic carbon, sum of bases, P, N, granulometry, and porosity showed a greater spatial variability, and FP02 showed a greater number of properties with high spatial variability compared to the other areas. Although the occurrence of plants and the production of Brazil nut fruits (Bertholletia excelsa) were associated with the classes and the physical and chemical properties of the soil, pyxidium production differed between areas. In general, soil physical properties were limiting factors for Brazil nut production and/or higher tree occurrence. Filipinas environment showed a low fruit production and a greater spatial variability of soil properties compared to Cachoeira.
Soils with dark subsurface horizons in saline basins in the Brazilian Pantanal
(Sociedade Brasileira de Ciência do Solo, 2021-11-30) Menezes, Andressa Rosas de; Fontana, Ademir; Anjos, Lúcia Helena Cunha dos; Pereira, Marcos Gervasio; Schiavo, Jolimar Antônio
Soils in the Brazilian Pantanal classified as Espodossolos and registered in the literature diverge from the central concept of pedogenesis by podzolization, especially due to the high values of pH and basic cations, although the morphology is similar to that of spodic horizons. In this sense, this study hypothesized that the neutral to alkaline conditions along the edges of the saline basins in the Lower Nhecolândia region do not inhibit the podzolization process nor the development of spodic soils. The objectives were to analyze the attributes of soils with spodic features and evaluate whether they correspond to a podzolization process. Four profiles in a transect in Lower Nhecolândia were selected, where the morphology indicated the presence of a spodic horizon. Three profiles (P1, P2 and P4) were located in a bay and one in the transition between a bay and a “cordilheira” (small elevation between lagoons) (P3). The soils were analyzed for particle size, chemistry and X-ray fluorescence (XRF), as well as organic carbon (C org), total carbon (TC) and XRF of the nodules. The complexity of features and characteristics of soil profiles in the Lower Nhecolândia region indicate multiple pedogenetic processes in this environment. The characteristics of all profiles denote a redoximorphic process: poor profile development (except for P3), mottles formed by precipitation of Fe and Mn oxides, as well as presence of Fe and Mn nodules. The organic matter content of these nodules is mostly greater than or equal to that of the surrounding material, and aluminum is relatively not higher than in the fine earth. This reinforces a rexodimorphic process in the horizons with spodic features. The occurrence of sodic and solodic characters, as well as clay accumulation in P3 also characterize the sodification process. The neutral to alkaline pH values in water, high sum of bases and low C org and Al oxide contents of the studied soils all contradict the occurrence of a podzolization process. However, Fe, Al and C org accumulation in the nodules and some B horizons indicate a spodic character. Also, the fact that SiBCS criteria classify the studied soils as Espodossolos indicates the relevance of establishing limits for chemical attributes, which would adjust the taxonomy of soils with a spodic character according to their pedogenesis.
Taxonomia de solos desenvolvidos sobre depósitos sedimentares da formação Solimões no estado do Acre
(Bragantia, 2013-04-16) Santos, Lauana Lopes dos; Bernini, Thiago de Andrade; Pereira, Marcos Gervasio; Fontana, Ademir; Anjos, Lúcia Helena Cunha dos; Calderano, Sebastião Barreiros; Wadt, Paulo Guilherme Salvador; Moraes, André Geraldo de Lima
Os solos do Estado do Acre na maioria são formados sobre material de origem com grande influência da orogênese Andina, com elevados teores de Ca^2+, Mg^2+ e Al^3+ concomitantemente, associado às combinações diferenciadas dos valores da CTC, V e m. O objetivo deste trabalho foi caracterizar e classificar os solos de uma topossequência sobre material sedimentar da Formação Solimões, no município de Feijó, Acre. Foram abertas trincheiras em três pontos de uma topossequência: terço superior (P1), terço médio (P2) e terço inferior (P3). Os solos foram analisados quanto a morfologia, granulometria (areia, silte e argila), complexo sortivo (Ca^2+, Mg^2+, Na^+, K^+ e Al^3+), acidez potencial (H+Al), P assimilável, pH (água e KCl), superfície específica, ataque sulfúrico (óxidos de Fe, Al, Ti e Si), mineralogia (frações areia, silte e argila). Os solos foram classificados segundo o Sistema Brasileiro de Classificação de Solos (SiBCS, 2006) e apresentada uma proposta de classificação considerando as peculiaridades do solos da região. Os solos têm baixo grau de desenvolvimento pedogenético, com minerais da fração argila de alta atividade, além da presença de minerais primários, como feldspatos e plagioclásios, nas frações areia e silte. Os solos foram classificados segundo o SiBCS atual como Argissolo Vermelho Álitico plíntico (P1), Argissolo Acinzentado Distrófico plíntico (P2) e Cambissolo Háplico Ta Eutrófico típico (P3).