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All publications of “Waldir de Carvalho”

10 results

Mapping Soil Cation Exchange Capacity in a Semiarid Region through Predictive Models and Covariates from Remote Sensing Data

César da Silva Chagas, Waldir de Carvalho Júnior, Helena Saraiva Koenow Pinheiro, Pedro Armentano Mudado Xavier, Silvio Barge Bhering, Nilson Rendeiro Pereira, [...]

15/Oct/2018

ABSTRACT: Planning sustainable use of land resources requires reliable information about spatial distribution of soil physical and chemical properties related to environmental processes and ecosystemic functions. In this context, cation exchange capacity (CEC) is a fundamental soil quality indicator; however, it takes money and time to obtain this data. Although many studies have been conducted to spatially quantify soil properties on various scales and in different environments, not much is known about interactions between soil properties and environmental covariates in […]

Prediction of Topsoil Texture Through Regression Trees and Multiple Linear Regressions

Helena Saraiva Koenow Pinheiro, Waldir de Carvalho, César da Silva Chagas, Lúcia Helena Cunha dos Anjos, Phillip Ray Owens

04/Apr/2018

ABSTRACT: Users of soil survey products are mostly interested in understanding how soil properties vary in space and time. The aim of digital soil mapping (DSM) is to represent the spatial variability of soil properties quantitatively to support decision-making. The goal of this study is to evaluate DSM techniques (Regression Trees – RT and Multiple Linear Regressions – MLR) and the ability of these tools to predict mineral fraction content under a wide variability of landscapes. The study site was […]

Environmental Correlation and Spatial Autocorrelation of Soil Properties in Keller Peninsula, Maritime Antarctica

André Geraldo de Lima Moraes, Marcio Rocha Francelino, Waldir de Carvalho, Marcos Gervasio Pereira, André Thomazini, Carlos Ernesto Gonçalves Reynaud Schaefer

12/Dec/2017

ABSTRACT: The pattern of variation in soil and landform properties in relation to environmental covariates are closely related to soil type distribution. The aim of this study was to apply digital soil mapping techniques to analysis of the pattern of soil property variation in relation to environmental covariates under periglacial conditions at Keller Peninsula, Maritime Antarctica. We considered the hypothesis that covariates normally used for environmental correlation elsewhere can be adequately employed in periglacial areas in Maritime Antarctica. For that […]

Artificial neural networks applied for soil class prediction in mountainous landscape of the Serra do Mar

Braz Calderano Filho, Helena Polivanov, César da Silva Chagas, Waldir de Carvalho Júnior, Emílio Velloso Barroso, Antônio José Teixeira Guerra, [...]

01/Dec/2014

Soil information is needed for managing the agricultural environment. The aim of this study was to apply artificial neural networks (ANNs) for the prediction of soil classes using orbital remote sensing products, terrain attributes derived from a digital elevation model and local geology information as data sources. This approach to digital soil mapping was evaluated in an area with a high degree of lithologic diversity in the Serra do Mar. The neural network simulator used in this study was JavaNNS […]

Evaluation of statistical and geostatistical models of digital soil properties mapping in tropical mountain regions

Waldir de Carvalho Junior, Cesar da Silva Chagas, Philippe Lagacherie, Braz Calderano Filho, Silvio Barge Bhering

01/Jun/2014

Soil properties have an enormous impact on economic and environmental aspects of agricultural production. Quantitative relationships between soil properties and the factors that influence their variability are the basis of digital soil mapping. The predictive models of soil properties evaluated in this work are statistical (multiple linear regression-MLR) and geostatistical (ordinary kriging and co-kriging). The study was conducted in the municipality of Bom Jardim, RJ, using a soil database with 208 sampling points. Predictive models were evaluated for sand, silt […]

Conditioned latin hypercube method for soil sampling in the presence of environmental covariates for digital soil mapping

Waldir de Carvalho Júnior, César da Silva Chagas, Alexandre Muselli, Helena Saraiva Koenow Pinheiro, Nilson Rendeiro Pereira, Silvio Barge Bhering

01/Apr/2014

Soil sampling is one of the most important stages in soil surveys. However, in conventional soil surveys, sampling schemes have proven to be inadequate for digital soil mapping because they may affect the results obtained and, in addition, they do not allow statistical estimations to be performed. This study attempts to evaluate the conditioned Latin Hypercube Sampling (cLHS) method with four environmental covariates (elevation, slope, curvature and land cover/land use map), in comparison to random sampling, in allocating 100 sample […]

Topographic properties to differentiate Argisols

César da Silva Chagas, Ademir Fontana, Waldir de Carvalho Junior, Sandro Marcelo de Caires

01/Dec/2013

The topographic conditions controls many hydrological, geomorphological and pedological processes, affectting the solar radiation, pluvial precipitation, superficial water flow, evaporation, soil moisture and vegetation types, among others. Topographic properties derived from a digital elevation model were used to explain the differentiation between soils with an argillic horizon in the region of ”Mar de Morros” in the northwestern State of Rio de Janeiro. Eight soil profiles (four Red Argisols and four Red-Yellow Argisols) developed from noritic granulites, in the municipalities of […]

Integration of quickbird data and terrain attributes for digital soil mapping by artificial neural networks

César da Silva Chagas, Waldir de Carvalho Júnior, Silvio Barge Bhering

01/Jun/2011

This study evaluated different environmental variables in the digital soil mapping of an area in the northern region of Minas Gerais State, using artificial neural networks. The environmental variables terrain attributes (slope and compound topographic index), the quickbird bands 1, 2 and 3, and lithology were evaluated. The importance of each of the variables in the classification was tested. The “Java Neural Network Simulator” was used with the backpropagation learning algorithm. For each dataset a neural network was created to […]

Multivariate analysis of Argisols of the Brazilian Atlantic coast

Waldir de Carvalho Junior, Carlos Ernesto G.R. Schaefer, César da Silva Chagas, Elpídio Inácio Fernandes Filho

01/Oct/2008

The Brazilian Atlantic coast have has extreme environmental diversity, where is expressive the occurrence of Argisols, described and identified in several studies, that do not have exhausted the possibilities of interpretations. The objective of this study was to evaluate the main differences in the physical and chemical properties of Argisols of the Brazilian Atlantic coast by multivariate analysis, allowing inferences on their genesis and fertility. For this purpose, 91 soil profiles from the soil survey reports of the Project RADAMBRASIL were analyzed, […]

Testing ALES (Automated Land Evaluation System) in the microregions Chapecó and Xanxerê, Western Santa Catarina State, for bean crop

César da Silva Chagas, Waldir de Carvalho Junior, Nilson Rendeiro Pereira, Elpidio Inácio Fernandes Filho

01/Jun/2006

Land evaluation is a process that estimates the land use potential based on its properties. A large variety of analytic models can be used in this process. In Brazil, the two most widely used land evaluation systems are the “Sistema de Classificação da Capacidade de Uso da Terra” and “Sistema FAO/Brasileiro de Aptidão Agrícola das Terras”. Although different in several aspects, both require the crossing of countless environmental variables. ALES (Automated Land Evaluation System) is a computer program that allows […]