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Our aim was to test if ecological stages may influence the arbuscular mycorrhizal fungi (AMF), nematodes, and the soil chemical properties in agroforestry systems (AF), unassisted forest restoration (UFR), and natural ecosystem (Ne) located in the Brazilian Tropical and Subtropical regions. We collected soil samples to determine AMF, nematodes, soil pH, P, and soil organic carbon (SOC). AMF and nematode richness in the AF and Ne were similar in the tropical region. The redundancy analysis (RDA) indicated that the abundance of AMF and soil nematodes was mainly affected by soil pH, P, and SOC. Differences were associated with (1) ecological stages, as we found differences in AMF and nematode abundance as affected by habitat simplification, and (2) changes in soil pH, SOC, and P. Our work increases the understanding of the AMF and soil nematode community in the rhizosphere of AF and Ne in tropical and subtropical regions.

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This work focuses on evaluating the spatial variability of chemical attributes of soils under different agricultural use and native forest, indicating which are the possible indicator attributes of changes in environmental, through the use and management of the soil. The study was carried out in the southern region of the Amazonas state, in an Argissolo Vermelho-Amarelo (Ultisol). Sampling grids were established measuring: 90 m × 70 m with regular soil collection spacing of 10 m for the guarana and forest areas; 90 m × 56 m spaced at 10 m × 8 m for annatto area; and 54 m × 42 m with spacing between points of 6 m for the cupuaçu area, totaling 80 sampling points in each area, with soil samples collected at depths of 0.0-0.05; 0.05-0.10 m and 0.10-0.20 m. The following attributes were determined: pH, Al3+, K+, Ca2+, Mg2+, P, H + Al, CEC, V% and m%. Descriptive, geostatistical and multivariate statistical analyzes were performed. The results show that it is possible to state that the descriptive, geostatistical and multivariate statistical techniques were able to identify the difference between the spatial variability of the attributes according to each specific use of individual soils. The multivariate analysis made it possible to select the attributes that most contribute to the variability of these soils, and with that, it was found that the forest showed less spatial variability in the surface layer, with higher reach values by scaled semivariograms.

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The south of the Brazilian Amazon is one of the largest cattle-producing regions in Brazil, however, most of the pastures are in low fertility soils. Thus, cattle breeders compensate for the low production of pastures, increasing the size of the areas, generating more deforestation and burning. These practices increase the chemical degradation process of Amazonian soils, making them increasingly infertile when improperly managed. With this, the objective of the work was to evaluate the impacts caused in the chemical attributes of soils, in areas under forest-to-pasture conversion, in the south of the Brazilian Amazon. The study was carried out in the district of União Bandeirantes, in an area of forest and two areas with pastures (brachiaria and mombaça grass). In the field, soil samples were collected at two depths (0.00-0.10 and 0.10-0.20 m), to carry out chemical analyzes. Further, uni, bi and multivariate statistical analyzes were carried out, besides geostatistical analyzes were carried out to study spatial variability and management zones. The conversion of forest to pasture increased the pH and exchangeable bases levels, reducing the availability of exchangeable aluminum and potential acidity, however, it induces losses of phosphorus and organic carbon from the soil. Among the pasture environments, the mombaça grass area presented higher fertility. Greater spatial variability of chemical attributes was observed in the environment with mombaça grass, indicating greater heterogeneity in the distribution of attributes in the area. We attribute this behavior to the higher grazing intensity and the micro-reliefs in the area that direct the flow of water and nutrients.

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Fruticulture in the Amazonian Rainforest is one of the main causes of deforestation, biodiversity loss, and soil erosion. Fruticulture plays a key role in the soil traits and soil organic matter (SOM) compartments by altering the soil ecosystem. Our aim was to assess the influence of Forest-Fruticulture conversion on soil traits, and SOM fractions in Brazil's Legal Amazon. The experiment was carried out in field conditions using four land uses as main treatments: Bixa orellana, Theobroma grandiflorum, Paullinia cupana, and the Amazon Rainforest. The soil physicochemical traits were analyzed using samples that were collected from 0-5, 5-10, and 10-20 cm soil depth by using grids (10 × 10 m) with 36 sampling points. Our results showed that the Fruticulture promoted an increase in bulk density, GMD, aggregate diameter, soil porosity, gravimetric moisture, sand, clay, carbon associated with humic acid, and, the sum of bases (K+, Ca2+, and Mg2+), while the Amazon Rainforest showed the highest values of silt, soil P content, SOC, p-SOC, m-SOC, carbon associated with fulvic acid, humine, and soil C stock. Overall, the fruticulture farming systems have negative effects on SOM compartments. The results of our study highlight the importance of considering fruticulture with endemic plant species by promoting soil fertility and soil aggregation.

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The Amazon rainforest region presents a phytophysiognomy that ranges from savannas to cerrados, all of them intimately associated to climate and soil characteristics. Evidence has been given that plant growth and development are affected by soil quality and seasonality, thus making it crucial to understand them and how they are related to each other in order to grasp the dynamics of the whole ecosystem. In this context, the goal of this research was to assess how seasonality, soil attributes, and root system biomass are related in natural cerrado, cerradão, and forest areas in southern Amazonas State, in Brazil. Soil samples were collected during dry (June/2018) and rainy (December/2018) seasons from three different layers 0.00­0.05m; 0.05­0.15m, and 0.15­0.30m deep. In each area ten sampling points were randomly chosen. Two kinds of soil samples were collected: the first using 4.0 cm height by 5.1cm internal-diameter soil sample rings; and the second were intact soil lumps. Physical and Chemical soil attributes assessed were macro-porosity (MaP), micro-porosity (MiP), total porosity (TP), soil density (SD), aggregates texture and stability (GMD and WAR), gravimetric humidity (HG), organic carbon (OC), exchangeable aluminum (Al3+), potential acidity (H+Al), sum of bases (SB), cation exchange capacity (CEC), and root biomass (RB). All data were analysed via Tukey t test and student T test to compare results between seasons and areas. Increasing vegetation density (cerrado < cerradão < forest) was followed by an increment in CEC and OC, showing the importance of these attributes to maintaining biodiversity in environments. In amazon cerrado, rainy season as well a sandier soil textures provided favourable conditions to the growth and development of plants' root system. Soil attributes were little affected by seasonality, that had greater effect on MiP, TP, SD, and OC, leading to lesser values for these variables during rainy season.

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The main cause of physical degradation in pasture areas is overgrazing, and when combined with poorly productive soils, it causes the loss of millions of hectares of agricultural soils a year. Thus, work is needed to indicate which physical attributes are most sensitive to degradation, generating information so that soil management can be proposed, with a view to economic, social, and environmental aspects. Therefore, the objective of the work was to evaluate the impacts caused on the physical attributes of the soil, in forests converted to pastures in northern Rondônia, Brazil. The study was carried out in three areas within the municipality of Porto Velho, Rondônia, one area with forest and two with pastures (brachiaria and mombaça grass). In the field, deformed soil samples were collected at a depth of 0.00-0.10 and 0.10-0.20 m in the three study areas. In the laboratory, physical analyses of texture, aggregates and porosity, compaction, and an additional analysis of soil organic carbon were carried out. Then, univariate, bivariate, and multivariate analyses were performed, as well as geostatistical analysis. The conversion of forest to pasture had a negative impact on aggregates, compaction, porosity, and accumulation of organic carbon in the soil. The studied environments are influenced by the high levels of sand and clay, which interfere in the aggregation, compaction, porosity, and accumulation of organic carbon in the soil. We observed greater spatial variability of physical attributes in the environment with mombaça grass and attributed this to the greater grazing and trampling intensity of the animals.

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The crop systems adopted in the Amazônia region have been studied several times in terms of the variability and to indicate the soil attributes more sensitive to the different crops. Thus, the objective of this work was to apply multivariate techniques in order to identify the chemical attributes most sensitive to environmental changes in different crop systems in Western Amazonia, Brazil. The research was conducted in five rural properties located in the Humaitá city region, Western Amazonia, Brazil. There were selected four environments with natural characteristics (Native Forest - NF) and five cropping systems (Grazing, Cassava, Açaí, Agroforestry and Reforestation). In the selected areas, soil samples were collected at depths layers of 0.0-0.05 m; 0.05-0.1 m and 0.1-0.2 m and the following chemical analyzes were performed: pH in water, Ca2+, Mg2+, K +, Resin-P, phosphorus bio-available particulate (Pbp), OC, Al3+, H++Al3+ and from these results SB, T, t, m% and V% were calculated. Multivariate statistical techniques were used to verify similarities between the crop systems in the attempt to relate the crops grown and the chemical attributes. The multivariate analysis was essential in the crop systems distinction, as well as to describe the relationship with the chemical properties. The results demonstrate and reinforce the existing variability between crop systems, with emphasis on the variation in crop systems, compared to natural environments. (AU)

Os sistemas de cultivos adotados na região Amazônica vêm sendo utilizados em diversos estudos em termo da variabilidade exercida pelas práticas de manejo e até mesmo indicar aqueles atributos mais sensíveis a esses manejos. Assim, o objetivo deste trabalho foi aplicar técnicas multivariadas a fim de identificar os atributos químicos mais sensíveis às mudanças ambientais em diferentes sistemas de cultivo na Amazônia Ocidental, Brasil. A pesquisa foi realizada em cinco propriedades rurais localizadas na região de Humaitá, Amazônia Ocidental. Foram selecionados quatro ambientes com características naturais (Floresta Nativa ­ FN) e cinco ambientes cultivados (Pastagem, Mandioca, Açaí, Agrofloresta e Reflorestamento). As amostras de solos nas áreas selecionadas foram coletadas nas profundidades de 0,0-0,05 m; 0,05-0,1 m e 0,1- 0,2 m. Foram realizadas as seguintes análises químicas: pH em água, Ca2+, Mg2+, K+, Presina, CO, Al3+,H ++Al3+ e a partir do resultado dessas análises foram calculadas a SB, T, t, m% e V%. Utilizaram-se técnicas de estatística multivariada para verificar semelhanças entre as práticas de manejo na tentativa de agrupar os sistemas de uso/atributos químicos. A análise multivariada foi preponderante na distinção dos sistemas de cultivos estudados, bem como caracterização da relação com as propriedades químicas. Os resultados demonstram e reforçam a variabilidade existente entre os sistemas de cultivo, com ênfase na variação dos sistemas de cultivo, em comparação com os ambientes naturais. (AU)

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This study aimed to ascertain what soil attributes may be an indicator of natural and anthropic pedogenic changes in top grassland (TG), low grassland (LG), ecotone zone (EZ), and forest (F) in Western Amazonia. Twenty samples of the diagnostic horizons were collected from the studied pedoenvironments: TG (A 0.0-14 and Bi 0.30-0.66 m); LG (A 0.0-0.15 and Cg1 0.27-0.80 m); EZ (A 0.0-0.15 and Bi 0.32-0.50 m); and forest (F) (A1 0.0-0.15 and Bt1 0.67-0.10 m). Sand, silt, clay, particle density (PD),soil bulk density (BD),saturated soil hydraulic conductivity, calcium (Ca), magnesium (Mg), exchangeable aluminum (Al3+), potassium (K), sodium (Na), phosphorus (P), pH in water and KCl, and organic matter (OM) contents were calculated and submitted to variance analysis. LG is more related to OM and clay than SHC value. These same attributes characterized TG. EZ is highlighted by its higher values and relationship with Al and K. It was concluded that for TG, LG, EZ, and F top soil layers, 28% of natural and anthropic changes can be identified based on sand, clay, pH in KCl, and OM data; on the other hand, subsurface 23% of determinations can be attributed to pH in H2O, Al, Na, and sand.

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Studying particle size distribution is important to understand soil structure and formation processes. This research aimed to assess the fractal dimension of soil texture in Indian Dark Earth (IDE) areas in southern Amazonas state under different land uses, as follows: two areas in the municipality of Apuí, one growing cocoa and the other coffee; a grassland area in the municipality of Manicoré; and a forest area in the municipality of Novo Aripuanã. A sampling grid containing 88 collection points (intersecting points on the grid) was established in each area, measuring 80 x 42 m for the cocoa and coffee-growing sites, and 80 x 56 m and 60 x 42 m for the grassland and forest areas, respectively. Soil samples were collected in soil core and as clumps at a depth of 0.0-0.20m to determine the structural physical properties and texture of the soil. The following physical attributes were assessed: texture (PSD), bulk density (BD), macroporosity (Macro), microporosity (Micro), total porosity (TP) and aggregate stability (GMD and WMD). The fractal dimension (D) of the soil texture was determined, followed by analysis of variance and comparison of the means using Tukey's test (p≤0.05). Pearson's correlation was applied to assess the correlation between variables. There was a significant difference between the IDEs studied, with a higher D value in the cocoa-growing area in relation to the other sites. Additionally, the larger the clay fraction, the higher the D value. Fractal dimension (D) showed a positive correlation with sand, clay, BD, Macro, GMD and WMD, and a negative correlation with silt, micro, TP. Based on the D values obtained, the ADE cultivated with cocoa showed superior quality in relation to the other areas studied.KEYWORDS: Fractal dimension. Soil physics. Soil use. INTRODUCTION Applications of fractal geometry in soil science have shown that soil exhibits fractal characteristics, being a porous medium having different particle compositions, with irregular shape and self-similar structure (TYLER; WHEATCRAFT, 1989; KRAVCHENKO; ZHANG, 1998). Fractal geometry, proposed and established by Mandelbrot (1982), is a method for describing systems with non-characteristic scales and self-similarity. In recent years, this theory has been used to quantitatively describe the particle size distribution of soil, attracting the interest of pedologists worldwide (DENG et al., 2017). Particle size distribution is one of the most important physical characteristics of soil because of its significant influence on water flow and soil erosion (XU; LI; LI, 2013). In this respect, broad and precise knowledge of particle size distribution is vital to understanding soil structures and formation, since it is closely related to soil erosion, organic matter content and moisture content (DU et al., 2017). Deng et al. (2017) studied the fractal features of soil particle size distribution and found an association between fractal dimensions and the physical and chemical properties of the soil analyzed, indicating that the lower the fractal dimension, the worse the soil physical and chemical properties. Recently, the fractal method was applied to estimate soil structure and proved to be an efficient tool in analyzing soil Received: 01/04/2019 Accepted: 30/01/2020

Estudar a distribuição do tamanho das partículas é importante para entender a estrutura do solo e os processos de formação. Esta pesquisa teve como objetivo avaliar a dimensão fractal da textura do solo em áreas de Terra Preta de Índio (TPI) no sul do Estado do Amazonas sob diferentes usos da terra: duas áreas no município de Apuí, uma com cultivo de cacau e outra de café; uma área de pastagem no município de Manicoré; e uma área florestal no município de Novo Aripuanã. Uma malha de amostragem contendo 88 pontos de coleta (pontos de interseção na grade) foi estabelecida em cada área, medindo 80 x 42 m para as áreas de cacau e café, e 80 x 56 m e 60 x 42 m para as áreas de pastagem e floresta, respectivamente. Amostras de solo foram coletadas em torrões a uma profundidade de 0,0-0,20 m para determinar as propriedades físicas estruturais e a textura do solo. Os seguintes atributos físicos foram avaliados: textura, densidade do solo (DS), macroporosidade (Macro), microporosidade (Micro), porosidade total (PT) e estabilidade de agregados (DMG e DMP). Determinou-se a dimensão fractal da textura do solo (D), seguida da análise de variância e comparação das médias pelo teste de Tukey (p≤0,05). A correlação de Pearson foi aplicada para avaliar a correlação entre as variáveis. Houve uma diferença significativa entre as TPIs estudadas, com um maior valor D na área de cultivo de cacau em relação aos outros locais. Além disso, quanto maior a fração argila, maior o valor de D. A dimensão fractal (D) apresentou correlação positiva com areia, argila, DS, Macro, DMG e DMP, e correlação negativa com silte, micro, PT. Com base nos valores de D obtidos, as TPIs cultivadas com cacau apresentaram qualidade superior em relação às demais áreas estudadas.PALAVRAS-CHAVES: Dimensão Fractal. Física do solo. Uso do solo. REFERENCES ALVARENGA, R. C.; FERNANDES, B.; SILVA, T. C. A.; RESENDE, M. Estabilidade de agregados de um Latossolo Roxo sob diferentes métodos de preparo do solo e de manejo da palha do milho. Revista Brasileira de Ciência do Solo, Viçosa, v. 10, n. 2, p. 273-277, 1986.

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Studies related to the monitoring of soil quality by physical attributes are important for the evaluation and maintenance of the sustainability of agricultural systems, besides indicating the appropriate management of the environment, aiming at its conservation and productivity. The objective of this study was to evaluate the stability of aggregates and organic carbon after the application of gypsum, soil scarification and a succession of crops. The treatments consisted of an absence and addition of gypsum, absence and presence of soil scarification, and three systems of crops in succession. The experimental design was made of randomized blocks, in a 2x2x4 factorial scheme, with eight replications. The aggregates were evaluated as stabled in water and soil organic carbon content. The treatment where gypsum was applied, as well as the soybean/maize/brachiaria/fallow (SMBF) succession system, presented better results in soil aggregation and higher levels of organic carbon.

Estudos relativos ao monitoramento da qualidade do solo pelos atributos físicos são importantes para a avaliação e manutenção da sustentabilidade dos sistemas agrícolas, além de sinalizar o manejo adequado do ambiente, visando à sua conservação e produtividade. Este trabalho teve por objetivo avaliar a estabilidade de agregados e teor de carbono orgânico, após a aplicação de gesso, escarificação do solo e sucessão de culturas. Os tratamentos consistiram na ausência e adição de gesso agrícola, ausência e presença de escarificação do solo, e três sistemas de sucessão de culturas. O delineamento experimental foi em blocos casualizados, em esquema fatorial 2x2x3 com oito repetições. Sendo avaliada a estabilidade dos agregados estáveis em água e teor de carbono orgânico do solo. O tratamento onde foi aplicado gesso agrícola e o sistema de sucessão SMBP apresentaram melhores resultados na agregação do solo e maiores teores de carbono orgânico.

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The soil and vegetation characteristics of the southern Amazonas region include highly weathered soils, high aluminum content and some hydromorphic conditions, its vegetation is composed from grasslands to small isolated trees and forest galleries along the rivers streams. In this way, this work aims to characterize and classify the soil in areas of clean field, dirty field, and forest in Humaitá region AM. Soil trenches were opened in the clean field, dirty field, and forest environments, soil profiles were morphologically characterized, and samples were collected from their horizons. Physical analysis of texture, dispersed clay in water, flocculation, bulk density, particle density and porosity were performed. The chemical analyzes included pH and KCl in water; Ca, Mg, K, Al, and; available P; H+Al and organic C; SiO2, Al2O3 and Fe2O3 sulfuric attack. The soils were classified according to criteria established by the Brazilian System of Soil Classification and Soil Taxonomy. The forest, dirty field (high) and clean field (low) showed different soil types, Typic Dystrudept for the first two environments and Typic Fluvaquents for last. Multivariate techniques expressed the similarity relations presenting between the different environments studied, characterizing, which are of great importance in the relation landscape-soil studies.

As características do solo e da vegetação da região sul do Amazonas incluem solos altamente intemperizados, alto teor de alumínio e algumas condições hidromórficas, sendo sua vegetaçãocomposta por pastos, pequenas árvores isoladas e galerias florestais ao longo dos cursos d'água. Desta forma, este trabalho tem como objetivo caracterizar e classificar o solo em áreas de campo limpo, campo sujo e floresta na região de Humaitá AM. As valas foram abertas no campo limpo, no campo sujo e nos ambientesflorestais, os perfis dos solos foram caracterizados morfologicamente e as amostras foram coletadas de seus horizontes. Análises físicas de textura, argila dispersa em água, floculação, densidade do solo, densidade de partículas e porosidade foram realizadas. As análises químicas incluíram pH e KCl em água; Ca, Mg, K, Al e; P disponível; H + Al e C orgânico; Ataque sulfúrico de SiO2, Al2O3 e Fe2O3. Os solos foram classificados de acordo com critérios estabelecidos pelo Sistema Brasileiro de Classificação de Solos e Taxonomia de Solos. A mata, o campo sujo (alto) e o campo limpo (baixo) apresentaram diferentes tipos de solo, distritos típicos para os dois primeiros ambientes e fluídicos típicos para o último. Técnicas multivariadas expressaram as relações de similaridade que se apresentam entre os diferentes ambientes estudados, caracterizando, que são de grande importância na relação paisagem-solo.

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The Amazon region has a great diversity of landscapes such as forests galleries, natural fields ("Cerrados Amazônicos"), dense forest, these environments made possible the formation of a broad class of soils over time. The aim of this study was to evaluate the physical and chemical properties of soils in different physiographic environments in southern Amazonas, Brazil. Three areas of representative physiographies were selected, all of them in natural conditions: natural field / forest and floodplain / dry land transitions, and corrugated relief areas. Soil samples were collected in layers of 0.0 to 0.20 and 0.80-1.0 m. From the samples collected the following physical analyzes were performed: particle size, bulk density, particle density, total porosity and saturated hydraulic conductivity; and chemical: exchangeable calcium, magnesium, aluminum and potassium available, phosphorus, potential acidity, pH and organic carbon. Based on the results of chemical analysis were calculated the sum of bases and base saturation. The results were submitted to multivariate statistics analysis, at the discretion of the principal component analysis (PCA). From the results it is clear that different physiographic environments studied influence the formation of different soil classes, featuring the diversity of Amazonian soils. The PCA allowed the distinction and formation of differentsimilarity groups, thus enabling to relate the physical and chemical properties with the physiographic formation in which they are inserted.

A região amazônica possui uma grande diversidade de paisagens, como galerias de florestas, campos naturais (Cerrados Amazônicos), floresta densa, possibilitando a formação de uma ampla classe de solos ao longo do tempo. O objetivo deste estudo foi investigar as propriedades físicas e químicas de solos em diferentes ambientes fisiográficos no sul do Amazonas, Brasil. Três áreas de fisiografias representativas foram selecionadas, todas em condições naturais: campo natural / floresta e transições de várzea / terra firme e áreas de relevo corrugado. Amostras de solo foram coletadas em camadas de 0,0 a 0,20 e 0,80-1,0 m. Das amostras coletadas foram realizadas as seguintes análises físicas: tamanho de partícula, densidade do solo, densidade de partículas, porosidade total e condutividade hidráulica saturada; e químico: cálcio trocável, magnésio, alumínio e potássio disponíveis, fósforo, acidez potencial, pH e carbono orgânico. Com base nos resultados da análise química foram calculados a soma das bases e saturação por bases. Os resultados foram submetidos à análise estatística multivariada, a critério da análise de componentes principais (PCA). A partir dos resultados, percebe-se que diferentes ambientes fisiográficos estudados influenciam a formação de diferentes classes de solos, caracterizando a diversidade de solos amazônicos. O PCA permitiu a distinção e formação de diferentes grupos de similaridade, permitindo relacionar as propriedades físico-químicas com a formação fisiográfica em que estão inseridos.

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As Terras Pretas Arqueológicas (TPAs) são solos de fertilidade que notoriamente são superiores à grande maioria dos solos típicos da região amazônica. Assim, o uso das TPAs intensificou-se devido às características químicas apresentadas por esses solos, como a alta concentração de nutrientes (fósforo, cálcio, magnésio). Nesse sentido, o objetivo deste estudo foi avaliar a distribuição espacial dos atributos químicos do solo em uma área de Terra Preta Arqueológica sob cultivo de cacau no município de Apuí (AM). O mapeamento de uma malha de 42 x 88 m, com espaçamento irregular de 6 x 8 m, totalizando 88 pontos, foi realizado e, em seguida, foram coletadas amostras de solo nas profundidades de 0,0-0,05; 0,05-0,10; (pH, O.C, Sto. C, (H + Al), P, K, Ca, Mg, SB, CEC e V%). Os dados foram analisados por meio de técnicas estatísticas descritivas e geoestatísticas. Os valores médios e medianos foram ajustados aos valores próximos, indicando distribuição normal, enquanto os atributos químicos do solo foram ajustados aos modelos de semivariogramas esféricos e exponenciais. A maioria dos atributos apresentou coeficiente de variação (CV) entre 12,1 e 60%, caracterizada como variabilidade média, as variáveis do estudo apresentaram diferentes faixas e a maioria teve forte dependência espacial. As técnicas geoestatísticas utilizadas permitiram os ajustes dos modelos teóricos que melhor representaram a semivariância experimental, possibilitando a construção de mapas temáticos da distribuição espacial dos valores dos atributos da área estudada.

The Black Archaeological Lands (TPAs) are fertility soils that are notoriously superior to the vast majority of typical soils in the Amazon region. Thus, the use of TPAs ​​has intensified due to the chemical characteristics presented by these soils, such as the high concentration of nutrients (phosphorus, calcium, magnesium). In this sense, the objective of this study was to evaluate the spatial distribution of the chemical attributes of the soil in an area of ​​Terra Preta Arqueológica under cocoa cultivation in the city of Apuí (AM). The mapping of a mesh of 42 x 88 m, with irregular spacing of 6 x 8 m, totaling 88 points, was carried out and, then, soil samples were collected at depths of 0.0-0.05; 0.05-0.10; (pH, O.C, Sto. C, (H + Al), P, K, Ca, Mg, SB, CEC and V%). The data were analyzed using descriptive and geostatistical statistical techniques. The mean and median values ​​were adjusted to the close values, indicating normal distribution, while the chemical attributes of the soil were adjusted to the models of spherical and exponential semivariograms. Most of the attributes presented a variation coefficient (CV) between 12.1 and 60%, characterized as average variability, the study variables had different ranges and most had a strong spatial dependence. The geostatistical techniques used allowed the adjustments of the theoretical models that best represented the experimental semivariance, allowing the construction of thematic maps of the spatial distribution of the values ​​of the attributes of the studied area.

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O conhecimento da distribuição espacial da temperatura, umidade do solo e emissão de CO2 é fundamental para entender o solo como fonte ou dreno de CO2, pois as alterações quanto ao uso e manejo influenciam esta dinâmica. O presente trabalho teve como objetivo investigar, a temperatura, umidade do solo e emissão de CO2 em uma área sob pastagem na região de Humaitá, AM. Demarcou-se uma área de 70 x 70 m, com espaçamento regular de 10 m, totalizando 64 pontos, as medições foram realizadas no período chuvoso e seco. Emissão de CO2 e a temperatura do solo foram registradas utilizando-se de câmara de fluxo portátil e sensor de temperatura do sistema LI-COR (LI-8100). A umidade foi avaliada utilizando sistema portátil TDR, em seguida foram realizadas análises estatísticas descritivas e geoestatísticas. A área de pastagem apresentou maior emissão de CO2 do solo no primeiro período de coleta, caracterizado como período chuvoso.  Variações espaciais da emissão de CO2 estão intimamente relacionadas com as variáveis climáticas entre os períodos seco e chuvoso.(AU)

Knowledge of the spatial distribution of temperature, soil moisture and CO2 emissions is essential to understand the soil as a source or drainage of CO2, as changes in use and management influence this dynamic. This study aimed to investigate the temperature, soil moisture and CO2 emissions in an area under pasture in Humaitá, AM. An area was demarcated at 70 x 70 m, with regular spacing of 10 m, totaling 64 points, measurements were carried out in both the rainy and dry season. CO2 emissions and soil temperature were recorded using portable flow chamber and temperature sensor LI-COR system (LI-8100). Moisture was assessed using portable system TDR, with subsequent descriptive statistical and geostatistical analysis. The pasture had higher emission of soil CO2 in the first collection period, characterized as rainy season. Spatial variations of CO2 emissions are closely related to climatic variables between dry and rainy periods.(AU)

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O conhecimento da distribuição espacial da temperatura, umidade do solo e emissão de CO2 é fundamental para entender o solo como fonte ou dreno de CO2, pois as alterações quanto ao uso e manejo influenciam esta dinâmica. O presente trabalho teve como objetivo investigar, a temperatura, umidade do solo e emissão de CO2 em uma área sob pastagem na região de Humaitá, AM. Demarcou-se uma área de 70 x 70 m, com espaçamento regular de 10 m, totalizando 64 pontos, as medições foram realizadas no período chuvoso e seco. Emissão de CO2 e a temperatura do solo foram registradas utilizando-se de câmara de fluxo portátil e sensor de temperatura do sistema LI-COR (LI-8100). A umidade foi avaliada utilizando sistema portátil TDR, em seguida foram realizadas análises estatísticas descritivas e geoestatísticas. A área de pastagem apresentou maior emissão de CO2 do solo no primeiro período de coleta, caracterizado como período chuvoso.  Variações espaciais da emissão de CO2 estão intimamente relacionadas com as variáveis climáticas entre os períodos seco e chuvoso.

Knowledge of the spatial distribution of temperature, soil moisture and CO2 emissions is essential to understand the soil as a source or drainage of CO2, as changes in use and management influence this dynamic. This study aimed to investigate the temperature, soil moisture and CO2 emissions in an area under pasture in Humaitá, AM. An area was demarcated at 70 x 70 m, with regular spacing of 10 m, totaling 64 points, measurements were carried out in both the rainy and dry season. CO2 emissions and soil temperature were recorded using portable flow chamber and temperature sensor LI-COR system (LI-8100). Moisture was assessed using portable system TDR, with subsequent descriptive statistical and geostatistical analysis. The pasture had higher emission of soil CO2 in the first collection period, characterized as rainy season. Spatial variations of CO2 emissions are closely related to climatic variables between dry and rainy periods.

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RESUMO

Sequential extraction or chemical fractionation of heavy metals allows inferences to be made about their origin, occurrence, bioavailability, toxic potential and environmental contamination. Thus, the present study aimed to assess the distribution of Cu, Mn, Ni, Pb and Zn among the different soil fractions and landscape compartments of a yellow latosol cultivated with vegetables. Soil samples were collected from five areas cultivated with tomato (Lycopersicon esculentum, Mill.), lettuce (Lactuca sativa), chili pepper (Capsicum annuum L.) and chard (Beta vulgaris L.) in different slope positions (upper, middle, lower), and four reference areas (native forest), at a depth of 0.00 - 0.20 m. Heavy metal levels were also assessed in water used to irrigate the crops and for human consumption by collecting 200 ml of water samples from reservoirs. The soil samples were sequentially fractionated to quantify the concentrations of adsorbed Cu, Mn, Ni, Pb and Zn in the exchangeable (EF), organic matter (OF), amorphous and crystalline iron oxide fractions (AFeOx and CFeOx). Landscape position only interfered significantly in heavy metal adsorption in the soil for Cu and Ni associated with CFeOx and Zn bound to the EF in the farming areas. The highest Cu, Ni, Pb and Zn levels were found in the fractions with less stable chemical bonds (bound to organic matter), in addition to a strong affinity between Cu, Zn and Mn and the oxide fractions (AFeOx + CFeOx). The low affinity of Pb and Ni for the AFeOx and CFeOx fractions indicates greater contamination potential for the water reservoirs. In the short term, organic matter is the main source of remediation for heavy metal contamination in soil, making it important to adopt conservation practices aimed at reducing OM losses.(AU)

Extrações sequenciadas ou fracionamento químico de metais pesados permitem inferências sobre origem, forma de ocorrência, biodisponibilidade, potencial de toxicidade e contaminação ambiental por esses elementos. Assim, o presente estudo foi desenvolvido com o propósito de avaliar a distribuição de Cu, Mn, Ni, Pb e Zn entre as diferentes frações do solo e compartimento da paisagem, de um Latossolo Amarelo sob cultivo de hortaliças. Foram coletadas amostras de solos de cinco áreas cultivadas com tomate (Lycopersicon esculentum, Mill.), alface (Lactuca sativa), pimentão (Capsicum annuum L.) e acelga (Beta vulgaris L.) em diferentes posições no relevo (topo, encosta, baixio) e quatro áreas de referência (mata nativa), na profundidade de 0,00 - 0,20 m. Também foram avaliados os teores de metais pesados na água destinada à irrigação das lavouras e ao consumo humano, coletando-se para isso, 200 ml de amostras de água dos reservatórios. As amostras de solo foram fracionadas sequencialmente para quantificação dos teores de Cu, Mn, Ni, Pb e Zn adsorvidos às frações trocável (FT), matéria orgânica (FO), óxido de ferro amorfo e cristalino (OxFeA e OxFeC). As posições da paisagem interferiram significativamente na adsorção de metais pesados no solo apenas para o Cu e o Ni ligados à OxFeC e para o Zn ligado à FT, nas áreas cultivadas. Os maiores teores de Cu, Ni, Pb e Zn no solo encontram-se nas frações com ligações químicas menos estáveis (ligados à matéria orgânica) sendo também encontrada forte afinidade de Cu, Zn e Mn às frações oxídicas (AFeOx + CFeOx). A baixa afinidade de Pb e Ni às OxFeA e OxFeC condiciona maior potencial de contaminação dos reservatórios hídricos. A curto prazo, a matéria orgânica é a principal fonte de remediação de metais pesados no solo, sendo importante a adoção de práticas conservacionistas que reduzam suas perdas.(AU)

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RESUMO

The soils of the Brazilian Amazon exhibit large geochemical diversity reflecting the different soil formation processes in an area covering 49% of the Brazilian territory. Soil contamination by heavy metals is one of the threats to the sustainability of this Biome but establishing quality reference values (QRVs) for the region is a challenging owing to the immense territorial area of the Amazon. This study aimed to determine the natural background of heavy metals in soils from the southwestern Brazilian Amazon in order to propose QRVs for Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sb, and Zn for alluvial sedimentary soils. One hundred and twenty-eight soil samples were collected at a depth of 0.0-0.2 m in sites with minimal anthropogenic interference. Soil sample digestion was based on the EPA 3051A method and metal concentrations were determined by ICP-OES. QRVs calculated for the southwestern Brazilian Amazon are among the lowest recorded in Brazil (mg kg-1): Ba (16.5), Cd (0.1), Cr (6.9), Cu (2.8), Fe (15.4), Mn (13.4), Ni (1.7), Pb (4.4), Sb (0.9), and Zn (5.7). The low metal concentration is likely a result of the sedimentary origin of the soils. The results of this study can serve as a basis for defining public policies to investigate the environmental impacts resulting from changes in land use in areas of the Brazilian Amazon.

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RESUMO

Having in mind the importance of knowing the variability and spatial correlation of soil properties in Indian Dark Earth (IDE), we evaluated in this study the variability and the spatial correlation of aggregates and carbon in an Ultisol under coffee cultivation in southern Amazonas. It was established a 48 x 88 m sampling grid spaced 06 x 08 m, totalling 88 sampling points. Then soil samples were collected at: 0.0-.05, 0.05-0.10, and 0.10-0.20 m layers. The spatial variability of the Mean Weighted Diameter (MWD) attributes, aggregates > 2 mm, < 2 mm, bulk density (BD) and organic carbon (OC) was analyzed by adjusting the simple semivariograms, while spatial correlations of the OC with aggregates and BD were analyzed by cross-semivariogram. We could conclude that there was spatial dependence in the variables, wherein the largest ones were observed at 0.0-0.05 m, except for Mean Weighted Diameter (MWD) and aggregates greater than 2.00 mm with larger range of values in depth from 0.05-0.10 and 0.10-0.20 m. The mean weight diameter and aggregate class attributes greater than 2.00 mm had negative spatial correlation with organic carbon at 0.0-0.05 m, while the smaller aggregates than 2.00 mm classes and bulk density correlated positively with organic carbon at 0.0-0.05 m and 0.10-0.20 m.

Considerando a importância do conhecimento da variabilidade e correlação espacial dos atributos do solo em Terra Preta de Índio (TPIs), avaliou-se neste trabalho a variabilidade e a correlação espacial de agregados e carbono em um Argissolo Amarelo eutrófico sob cultivo de café na região sul do Amazonas. Foi estabelecido um grid amostral com dimensões de 48 x 88 m e espaçamentos de 06 x 08 m, totalizando 88 pontos amostrais. Em seguida, foram coletadas amostras de solos nas profundidades: 0,0-0,05, 0,05-0,10, e 0,10-0,20 m. A variabilidade espacial dos atributos diâmetro médio ponderado (DMP), agregados > 2 mm, < 2 mm, densidade do solo (Ds) e carbono orgânico (CO) foi analisada ajustando os semivariogramas simples, enquanto as correlações espaciais do CO com agregados e Ds foram analisadas por semivariogramas cruzados. Concluiu-se que as variáveis apresentaram dependência espacial, e os maiores alcances são constatados na profundidade 0,0-0,05 m, exceto para DMP e agregados maiores que 2,00 mm com maiores valores de alcance na profundidade 0,05-0,10 e 0,10-0,20 m. Os atributos diâmetro médio ponderado e classes de agregados maior que 2,00 mm apresentam correlação espacial negativa com carbono orgânico na profundidade 0,0-0,05 m, enquanto a classes de agregados menor que 2,00 mm e densidade do solo apresentam correlação positiva com carbono orgânico nas profundidades 0,0-0,05 m e 0,10-0,20 m.

Assuntos

RESUMO

Sequential extraction or chemical fractionation of heavy metals allows inferences to be made about their origin, occurrence, bioavailability, toxic potential and environmental contamination. Thus, the present study aimed to assess the distribution of Cu, Mn, Ni, Pb and Zn among the different soil fractions and landscape compartments of a yellow latosol cultivated with vegetables. Soil samples were collected from five areas cultivated with tomato (Lycopersicon esculentum, Mill.), lettuce (Lactuca sativa), chili pepper (Capsicum annuum L.) and chard (Beta vulgaris L.) in different slope positions (upper, middle, lower), and four reference areas (native forest), at a depth of 0.00 - 0.20 m. Heavy metal levels were also assessed in water used to irrigate the crops and for human consumption by collecting 200 ml of water samples from reservoirs. The soil samples were sequentially fractionated to quantify the concentrations of adsorbed Cu, Mn, Ni, Pb and Zn in the exchangeable (EF), organic matter (OF), amorphous and crystalline iron oxide fractions (AFeOx and CFeOx). Landscape position only interfered significantly in heavy metal adsorption in the soil for Cu and Ni associated with CFeOx and Zn bound to the EF in the farming areas. The highest Cu, Ni, Pb and Zn levels were found in the fractions with less stable chemical bonds (bound to organic matter), in addition to a strong affinity between Cu, Zn and Mn and the oxide fractions (AFeOx + CFeOx). The low affinity of Pb and Ni for the AFeOx and CFeOx fractions indicates greater contamination potential for the water reservoirs. In the short term, organic matter is the main source of remediation for heavy metal contamination in soil, making it important to adopt conservation practices aimed at reducing OM losses.

Extrações sequenciadas ou fracionamento químico de metais pesados permitem inferências sobre origem, forma de ocorrência, biodisponibilidade, potencial de toxicidade e contaminação ambiental por esses elementos. Assim, o presente estudo foi desenvolvido com o propósito de avaliar a distribuição de Cu, Mn, Ni, Pb e Zn entre as diferentes frações do solo e compartimento da paisagem, de um Latossolo Amarelo sob cultivo de hortaliças. Foram coletadas amostras de solos de cinco áreas cultivadas com tomate (Lycopersicon esculentum, Mill.), alface (Lactuca sativa), pimentão (Capsicum annuum L.) e acelga (Beta vulgaris L.) em diferentes posições no relevo (topo, encosta, baixio) e quatro áreas de referência (mata nativa), na profundidade de 0,00 - 0,20 m. Também foram avaliados os teores de metais pesados na água destinada à irrigação das lavouras e ao consumo humano, coletando-se para isso, 200 ml de amostras de água dos reservatórios. As amostras de solo foram fracionadas sequencialmente para quantificação dos teores de Cu, Mn, Ni, Pb e Zn adsorvidos às frações trocável (FT), matéria orgânica (FO), óxido de ferro amorfo e cristalino (OxFeA e OxFeC). As posições da paisagem interferiram significativamente na adsorção de metais pesados no solo apenas para o Cu e o Ni ligados à OxFeC e para o Zn ligado à FT, nas áreas cultivadas. Os maiores teores de Cu, Ni, Pb e Zn no solo encontram-se nas frações com ligações químicas menos estáveis (ligados à matéria orgânica) sendo também encontrada forte afinidade de Cu, Zn e Mn às frações oxídicas (AFeOx + CFeOx). A baixa afinidade de Pb e Ni às OxFeA e OxFeC condiciona maior potencial de contaminação dos reservatórios hídricos. A curto prazo, a matéria orgânica é a principal fonte de remediação de metais pesados no solo, sendo importante a adoção de práticas conservacionistas que reduzam suas perdas.

Assuntos

RESUMO

Heavy metals occur naturally in the soil as a product of rock weathering and, are commonly associated with environmental pollution and toxicity to living beings. This association deserves much attention since some heavy metals, such as Fe, Mn, Cu, Zn, and Ni, are essential to plants. Our attention should thus be drawn not only to the element itself, but also to its contents in the soil. This is because its occurrence and quantities are covariates of the geomorphic, geologic, pedologic, and anthropogenic diversity. In this context, the present study aimed to determine the natural contents of heavy metals in the soils of three physiographic regions of the south of Amazonas state, comparing them to natural contents in some other Brazilian soils. Twenty-four soil samples were collected in three physiographic regions (field/forest, animated relief, and flooded/non-flooded areas), in the superficial and subsurface horizons. The digestion of the samples was based on the EPA-3051A method and the determination by atomic absorption spectrophotometry (AAnalyst 800 Perkin Elmer). The results indicate a low potential of soils from the south of Amazonas in supplying heavy metals, which were found in the following decreasing order: Ba>Fe>Cr>Pb>Zn>Cu>Mn>Co>Cd. The natural heavy metal contents vary depending on the type of soil, weathering level, and physiographic regions, and are similar or inferior to those observed in other regions of the country; with Neosols presenting the highest natural contents; and Cambisols, the lowest, for most of the metals evaluated.(AU)

Os metais pesados ocorrem naturalmente no solo como produto do intemperismo das rochas e, comumente, são associados com poluição ambiental e toxidade aos seres vivos. Essa relação merece atenção mais cautelosa, uma vez que alguns são essenciais às plantas como Fe, Mn, Cu, Zn e Ni. Assim, a preocupação deve estar voltada não apenas ao elemento em si, mas aos teores desses no solo, visto que sua ocorrência e quantidade são covariativas da diversidade geomorfológica, geológica, pedológica e antrópica. Neste sentido, objetivou-se determinar os teores naturais dos metais pesados nos solos de três regiões fisiográficas da região Sul do Amazonas, comparando-os com os teores naturais de alguns solos do país. Foram coletadas 24 amostras de solo em três regiões fisiográficas (Campo/Floresta, Relevo Movimentado e Várzea/Terra Firme), nos horizontes superficiais e subsuperficiais. A digestão das amostras baseou-se no método EPA-3051A, e a determinação com espectrofotometria de absorção atômica (AAnalyst 800 Perkin Elmer). Os resultados indicam baixo potencial dos solos do Sul do Amazonas em suprir metais pesados, sendo os maiores teores encontrados na seguinte ordem decrescente: Ba>Fe>Cr>Pb>Zn>Cu>Mn>Co>Cd. Os teores naturais de metais pesados variam em função da classe de solo, grau de intemperismo e das regiões fisiográficas e são semelhantes ou inferiores aos observados em outras regiões do país; com Neossolos apresentando teores naturais mais elevados e, os Cambissolos, os mais baixos, para a maioria dos metais avaliados.(AU)

Assuntos