Spatial variability of chemical indicators of Amazon agricultural soils through geomultivariate statistics, Brazil.

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.

Epidemiological indicators of Chagas disease in the metropolitan region of Salvador, Bahia, Brazil.

BACKGROUND: Chagas disease (CD) is caused by Trypanosoma cruzi and transmitted by triatomines. Historical information from the 20th century demonstrates T. cruzi records in the metropolitan region of Salvador (MRS), the third largest urban agglomeration in the Brazilian Northeast and the eighth largest in Brazil, an area with intense migratory activity from CD-endemic regions. Therefore, this study aimed to evaluate CD indicators (prevalence and mortality) in the MRS. METHODS: A mixed ecological and descriptive study was conducted using secondary data. We analyzed data from 2008 to 2015: deaths due to CD, self-reported cases of CD, and blood donors that were non-negative for T. cruzi infection. RESULTS: São Francisco do Conde was one of the municipalities with the highest mortality rates due to CD. The seroprevalence rates varied by year and municipality; those with the highest values were 2008: Vera Cruz, 2009: Mata de São João, 2010: Dias D'Ávila, 2011 and 2015: São Francisco do Conde, 2012: São Sebastião do Passé, and 2013 and 2014: Pojuca. Spatial correlations between the municipalities were not detected. CONCLUSIONS: We conclude that CD is present in the MRS. The indicators analyzed in the MRS are below-state-level data. Given the importance of indicator analysis for the surveillance and control of CD at the state and national levels, it is important to strengthen the surveillance program at the municipal level, including the regions classified as low risk for T. cruzi vector transmission.

Epidemiological indicators of Chagas disease in the metropolitan region of Salvador, Bahia, Brazil

ABSTRACT Background: Chagas disease (CD) is caused by Trypanosoma cruzi and transmitted by triatomines. Historical information from the 20th century demonstrates T. cruzi records in the metropolitan region of Salvador (MRS), the third largest urban agglomeration in the Brazilian Northeast and the eighth largest in Brazil, an area with intense migratory activity from CD-endemic regions. Therefore, this study aimed to evaluate CD indicators (prevalence and mortality) in the MRS. Methods: A mixed ecological and descriptive study was conducted using secondary data. We analyzed data from 2008 to 2015: deaths due to CD, self-reported cases of CD, and blood donors that were non-negative for T. cruzi infection. Results: São Francisco do Conde was one of the municipalities with the highest mortality rates due to CD. The seroprevalence rates varied by year and municipality; those with the highest values were 2008: Vera Cruz, 2009: Mata de São João, 2010: Dias D'Ávila, 2011 and 2015: São Francisco do Conde, 2012: São Sebastião do Passé, and 2013 and 2014: Pojuca. Spatial correlations between the municipalities were not detected. Conclusions: We conclude that CD is present in the MRS. The indicators analyzed in the MRS are below-state-level data. Given the importance of indicator analysis for the surveillance and control of CD at the state and national levels, it is important to strengthen the surveillance program at the municipal level, including the regions classified as low risk for T. cruzi vector transmission.

Soil chemical attributes in areas under conversion from forest to pasture in southern Brazilian Amazon.

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.

Forest-Fruticulture Conversion Alters Soil Traits and Soil Organic Matter Compartments.

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.

Ecdysone modulates both ultrastructural arrangement of hindgut and attachment of Trypanosoma cruzi DM 28c to the rectum cuticle of Rhodnius prolixus fifth-instar nymph.

Studies on the effects of azadirachtin treatment, ecdysone supplementation and ecdysone therapy on both the ultrastructural organization of the rectum in 5th-instar nymph of Rhodnius prolixus and the ex vivo attachment behavior of Trypanosoma cruzi under these experimental conditions were carried out. Control insects had a typical and significant organization of the rectum cuticle consisted of four main layers (procuticle, inner epicuticle, outer epicuticle, and wax layer) during the entire period of the experiment. Both azadirachtin treatment and ecdysone supplementation avoid the development of both outer epicuticle and wax layer. Oral therapy with ecdysone partially reversed the altered organization and induce the development of the four main rectal cuticle layers. In the same way, the ex vivo attachment of T. cruzi to rectal cuticle was blocked by azadirachtin treatment but ecdysone therapy also partially recovered the parasite adhesion rates to almost those detected in control insects. These results point out that ecdysone may be a factor responsible - directly or indirectly - by the modulation of rectum ultrastructural arrangement providing a superficial wax layer to the attachment followed by metacyclogenesis of T. cruzi in the rectum of its invertebrate hosts.

Seasonality, soil attributes and root biomass in cerrado, cerradão and forest environments, western Amazon

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.

Physical soil attributes in areas under forest/pasture conversion in northern Rondônia, Brazil.

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.

Pedotransfer functions to estimate some soil properties in Indian Black Earth, south of Amazonas State.

Agriculture needs methodologies that assist in the determination of soil attributes and variability mapping attributes with greater levels of detail. Therefore, the objective of this research was to evaluate magnetic susceptibility as auxiliary variable for estimating soil attributes in areas of Indian Black Earths in the south of Amazonas State. Three Indian Black Earth areas are located in the municipalities of Apuí and Manicoré - Amazonas, under uses with coffee, cocoa and pasture. The soils were collected at the crossing points in the depth of 0.00 - 0.20 m, making a total of 88 sampling points/area, and totaling 264 samples. The points were georeferenced for geostatistical modeling. After that, physical and chemical analyzes were performed to obtain the values ​​of soil and magnetic susceptibility attributes. Descriptive statistics, Pearson correlation, linear regression and geostatistical analyzes were applied for Pedotransfer Function modeling and the spatial variability of the analyzed attributes. Magnetic susceptibility showed a high degree of spatial dependence in the study areas, high range values, correlating with most of the assessed attributes, mainly physical, indicating potential in the prediction of the attributes in these environments. Pedotransfer functions vary among IBE's sites in attribute prediction, ensuring moderate estimates for predicting soil attributes in IBE's areas.

Attributes of pedoindicator soils in areas cultivated with typical crops in the Western Amazon, Brazil / Atributos de solos pedoindicadores em áreas cultivadas com culturas típicas na Amazônia Ocidental, Brasil

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)

Óbitos evitáveis em crianças menores de cinco anos em Passos/MG / Avoidable deaths in children under five years in Passos/MG / Muertes evitables de niños menores de cinco años Passos/MG

Objetivo: Descrever as principais causas de óbitos evitáveis em crianças menores de cinco anos no município de Passos, Minas Gerais, entre os anos de 2010 a 2018, segundo a "Lista Brasileira de Causas de Mortes Evitáveis". Método: Pesquisa descritiva, retrospectiva, com abordagem quantitativa, por meio dos dados coletados pela base de dados do Sistema de Informação sobre Mortalidade (SIM), posteriormente digitados em planilhas do Excel 2010 e analisados por estatística descritiva simples. Resultados: Houve maior ocorrência de óbitos em crianças do sexo masculino, no período neonatal precoce. As causas mais prevalentes foram as reduzíveis por adequada atenção à mulher na gestação, seguida por adequada atenção ao recém-nascido. Conclusão: Há necessidade de maior envolvimento dos gestores em saúde quanto à assistência pré-natal, com implementação de ações que promovam a saúde e a prevenção de doenças e agravos, garantindo assim serviços de excelência para o atendimento destes grupos vulneráveis.(AU)

Objective: To describe the main causes of preventable deaths in children under five years of age in the municipality of Passos, Minas Gerais, between 2010 and 2018, according to the "Brazilian List of Causes of Avoidable Deaths". Method: Descriptive, retrospective research, with a quantitative approach, using data collected from the Mortality Information System (SIM) database, which were later entered into Excel 2010 spreadsheets and analyzed using simple descriptive statistics. Results: There was a higher occurrence of deaths in male children in the early neonatal period. The most prevalent causes were those that could be reduced by adequate care for women during pregnancy, followed by adequate care for the newborn. Conclusion: There is a need for greater involvement of health managers in terms of prenatal care, with the implementation of actions that promote health and the prevention of diseases and injuries, thus guaranteeing excellent services for the care of these vulnerable groups.(AU)

Objetivo: Describir las principales causas de muertes evitables en menores de cinco años en el municipio de Passos, Minas Gerais, entre 2010 y 2018, según la "Lista Brasileña de Causas de Muertes Evitables". Método: Investigación descriptiva, retrospectiva, con enfoque cuantitativo, utilizando datos recolectados de la base de datos del Sistema de Información de Mortalidad (SIM), que luego fueron ingresados en hojas de cálculo Excel 2010 y analizados mediante estadística descriptiva simple. Resultados: Hubo una mayor incidencia de muertes en niños varones en el período neonatal temprano. Las causas más prevalentes fueron las que podrían reducirse con una atención adecuada a la mujer durante el embarazo, seguida de una atención adecuada al recién nacido. Conclusión: Existe la necesidad de una mayor participación de los gestores de salud en materia de atención prenatal, con la implementación de acciones que promuevan la salud y la prevención de enfermedades y lesiones, garantizando así excelentes servicios para la atención de estos grupos vulnerables.(AU)

Fractal features of soil texture and physical attributes in indian dark earth under different uses in Western Amazon / Características fractais da textura e atributos físicos do solo em áreas com terra preta de índio sob diferentes usos na Amazônia Ocidental

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.

The stability of aggregates and organic carbon content after the application of gypsum, soil scarification and a succession of agricultural crops / A estabilidade dos agregados e do teor de carbono orgânico após a aplicação de gesso, escarificação do solo e uma sucessão de culturas agrícolas

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.

Soils characterization and classification in clean field, dirty field and forest areas in amazonian environments / Caracterização e classificação de solos em área de campo limpo, campo sujo e floresta em ambientes amazônicos

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.

Physical and chemical properties of soils in different physiographic environments in the southern Amazonas region / Atributos físicos e químicos de solos em diferentes ambientes fisiográficos na região sul do Amazonas, Brasil

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.

Spatial variation of chemical attributes in archaeological dark earth under cocoa cultivation in Western Amazon / Variação espacial de atributos químicos em terra pr eta arqueológica sob cultivo de cacau na amazonia ocide ntal

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.

Variability and spatial correlation of aggregates and organic carbon in indian dark earth in Apuí region, AM / Variabilidade e correlação espacial de agregados e carbono orgânico em terra preta de índio na região do Apuí, AM

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.

Spatial variability of aggregates and organic carbon under three different uses of indian black earth in southern Amazonas / Variabilidade espacial de agregados e carbono orgânico sob três diferentes usos de terra preta de índio no sul do Amazonas

Indian Black Earths (IBEs) are distributed throughout the Amazon. They are characterized by their high chemical fertility and agricultural potential. IBEs have high organic carbon, favouring the improvement of soil structure. This work aimed to evaluate the aggregates and organic carbon (OC) spatial variability in different IBEs in southern Amazonas. We evaluated the organic carbon spatial variability, mean weight diameter (MWD), soil bulk density (b) and aggregate classes under three uses of soil: pasture, cocoa, and coffee. We collected 528 soil samples in a point grid according to its use at two depths: 0.0-0.05 m and 0.10-0.20 m. Results were subjected to variance, descriptive, and geostatistical analyses. We concluded that the soil use influenced the IBEs physical attributes soil behavior, concentrating the higher values of CO, aggregates > 2.00 mm, and MWD at 0.0-0.05 m in relation to b and aggregates < 2.00 mm where the higher values were the ones at 0.10-0.20 m. Aggregates < 2.00 mm (0.10-0.20 m) and OC (0.0-0.05 m) did not show spatial dependence, while the class of aggregates > 2.00 mm was the only attribute which represented to be a natural characteristic of the soil, with a strong spatial dependence, independently the land use and depth. There was no spatial relationship between the attributes studied and the geomorphic diversity.

As Terras Pretas de Índio (TPIs) encontram-se distribuídas por toda a Amazônia. Elas são caracterizadas pela alta fertilidade química e potencial agrícola. As TPIs possuem alto carbono orgânico, favorecendo a melhoria da estrutura do solo. Este trabalho teve como objetivo avaliar a variabilidade espacial dos agregados e do carbono orgânico (CO) em diferentes usos de TPIs no sul do Amazonas. Foi avaliado a variabilidade espacial do carbono orgânico, diâmetro médio ponderado (DMP), densidade do solo (b) e as classes de agregados sob três usos do solo: pastagem, cacau e café. Nas áreas estudas construiu-se um grid regular de pontos, de acordo com o uso do solo e nas profundidades, 0-0,05 m e 0,10-0,20 m, totalizando 528 amostras de solo. Os resultados foram submetidos à análise de variância, descritiva e geoestatística. O uso do solo influenciou o comportamento dos atributos físicos das TPIs, concentrando os valores mais altos de CO, agregados > 2.00 mm e DMP na profundidade 0,0-0.05 m em relação a b e agregados <2.00 mm, que assumiram valores mais altos na profundidade 0,10-0,20 m. Agregados < 2,00 mm (0,10-0,20 m) e CO (0,0-0,05 m) não apresentaram dependência espacial, enquanto a classe de agregados > 2,00 mm foi o único atributo que representou uma característica natural do solo, com forte dependência espacial, independentemente do uso e profundidade do solo. Não houve relação espacial entre os atributos estudados e a diversidade geomórfica.

Physical and geospatial attributes of inceptisols and ultisols under native vegetation in Humaitá, AM, Brazil / Atributos físicos e geoespaciais de cambissolo e argissolo de mata nativa em Humaitá, AM

Natural grasslands with savannah-like characteristics associated to forest mosaics are found within Southern and Eastern Amazonas, Western Rondônia and Northern Roraima, being conditioned to local edaphic factors. The aim of this study was to assess both physical and geospatial attributes of an Cambisol under natural grasslands and an Ultisol under a forest fragment in Humaitá - AM, Brazil. In each area, we established a sampling grid in the dimensions of 70 × 70 m, with regular sampling spacing of 10 m and three collection depths: 0.0-0.05, 0.05-0.10 and 0.10-0.20 m, totaling 192 sampling points. Macroporosity (MaP), microporosity (MiP), bulk density (Ds) and total porosity (TP) were determined by soil samples with preserved structure, using a volumetric ring. Soil resistance to penetration (SRP) was measured by an automatic penetrometer after being subjected to a 0.006 MPa tension. Data were submitted to descriptive statistics and geostatistics analysis. The soil under natural grasslands showed values considered critical of Ds, SRP, MaP at all evaluated depths, with significant values at 0.10-0.20 m layer of 1.54 kg dm-3; 2.08 MPa and 0.05 m3 m-3, respectively. Ultisol under the forest fragments showed higher range values and consequently greater geospatial continuity due to the assessed physical attributes, since this soil has a greater stability of its physical structure. Based on the physical properties of the soil, structural function ineffectiveness of the Ultisol is a key factor for the occurrence of grassland in this region.

Na porção sul e leste do Amazonas, oeste de Rondônia e norte de Roraima há ocorrência de campos naturais com características savânicas associadas a mosaicos florestais, condicionadas aos fatores edáficos locais. O objetivo deste estudo foi avaliar os atributos físicos e geoespaciais de um Cambissolo sob campos naturais e Argissolo sob fragmento florestal em Humaitá, AM. Em cada área foi estabelecida uma malha amostral nas dimensões de 70 × 70 m, com espaçamentos regulares de amostragem de 10 m e três profundidades de coleta: 0,0-0,05; 0,05-0,10 e 0,10-0,20 m, totalizando 192 pontos de coleta. Para as determinações da macroporosidade (MaP), microporosidade (MiP), densidade do solo (Ds) e volume total de poros (VTP) foram coletadas amostras com estrutura preservada, utilizando-se anéis volumétricos. Após serem submetidos a uma tensão de 0,006 MPa, as mesmas amostras foram utilizadas para medir a resistência do solo à penetração (RP), utilizando um penetrógrafo eletrônico. Os resultados foram submetidos às análises estatística descritiva e geoestatística. O solo sob campo natural apresentou valores considerados críticos de Ds, RP, MaP em todas as profundidades avaliadas, obtendo-se valores mais expressivos na profundidade de 0,10-0,20 m, da ordem de 1,54 kg dm-3; 2,08 MPa; e 0,05 m3 m-3, respectivamente. O Argissolo do fragmento florestal apresentou maiores alcances e consequente maior continuidade geoespacial correlativa aos atributos físicos avaliados, mediante a maior estabilidade da estrutura física desse solo. Com base nas características físicas do solo, a ineficiência das funções estruturais do Cambissolo é o fator determinante da ocorrência de vegetação campestre nessa região.

Chemical soil attributes evaluated by multivariate techniques and geostatistics in the area with agroforestry and sugarcane in Humaitá, AM, Brazil / Atributos químicos do solo avaliados por técnicas multivariadas e geoestatísticas em área com agrofloresta e cana-de-açúcar em Humaitá, AM, Brasil

Studies on the spatial behavior of soil attributes in the Amazon region are still very incipient. In this sense, the objective of this work was to evaluate the chemical attributes through multivariate techniques and geoestatistics in the area with agroforestry and sugarcane in Humaitá, AM, Brazil. The study was carried out in a farm in Humaitá city, Amazonas State. The studied area was divided into 70.00 m x 70.00 m meshes with a regular spacing of 10 m, totaling 64 points and then, soil samples were collected at 0.0-0.2 m and 0.4-0.6 m depths. We performed chemical analyses of the attributes of soil. Then, it was applied descriptive statistics, multivariate and geostatistics. In conclusion, our findings suggest that for most of the chemical attributes was observed spatial dependence in both areas, with DSD varying from weak to moderate, with prevalence of the weak one. The multivariate analysis was efficient in the selection of chemical soil attributes that best represented the agroforestry environments and sugarcane. The results of this study will serve as a basis for further studies on these environments and other systems within the region; moreover serving as a basis for agricultural planning aiming a better environmental sustainability.

Existe uma carência de estudos enfocando o comportamento espacial de atributos químicos no Amazonas. Neste sentido o objetivo deste trabalho foi avaliar os atributos químicos do solo por meio de técnicas multivariadas e geoestatística em área com agrofloresta e cana-de-açúcar em Humaitá, AM, Brasil. O estudo foi realizado em uma propriedade rural em Humaitá, Amazonas. Nestas áreas foram estabelecidas malhas de 70,00 m x 70,00 m, com espaçamento regular de 10,00 x 10,00 m totalizando 64 pontos e em seguida, coletadas amostras de solos na profundidade de 0,0-0,20 e 0,40 ­ 0,60 m. Foram determinados os atributos químicos (pH, MO, P, K, Ca, Mg, SB, CTC, V% e H+Al). Utilizaram-se técnicas de estatística descritiva, multivariada e geoestatística. Em conclusão, nossos resultados sugerem que, para a maioria dos atributos químicos foi observada dependência espacial em ambas as áreas, com DSD variando de fraca a moderada, com prevalência de um fraco e a análise multivariada foi eficiente na seleção de atributos químicos do solo que melhor representou os ambientes de agrofloresta e cana de açúcar.