Volume 37, Number 2, 2013

A good knowledge of the spatial distribution of clay minerals in the landscape facilitates the understanding of the influence of relief on the content and crystallographic attributes of soil minerals such as goethite, hematite, kaolinite and gibbsite. This study aimed at describing the relationships between the mineral properties of the clay fraction and landscape shapes by determining the mineral properties of goethite, hematite, kaolinite and gibbsite, and assessing their dependence and spatial variability, in two slope curvatures. To this end, […]

Although the influence of clay mineralogy on soil physical properties has been widely studied, spatial relationships between these features in Alfisols have rarely been examined. The purpose of this work was to relate the clay minerals and physical properties of an Alfisol of sandstone origin in two slope curvatures. The crystallographic properties such as mean crystallite size (MCS) and width at half height (WHH) of hematite, goethite, kaolinite and gibbsite; contents of hematite and goethite; aluminium substitution (AS) and specific […]

The floodplains of the Solimões River are areas periodically flooded with predominance of Gleisols,where have lived a large number of small farmers of the region. The purpose of this study was to characterize and classify five profiles of Gleysoils distributed in three floodplain areas of the Middle Amazon basin, located in the municipalities of Manacapuru and Iranduba. After the morphological description, the soil horizons were sampled to perform physical, chemical and mineralogical analyses. Similarly, significant gleization was observed in all […]

Digital mapping techniques can help reduce the lack of soil information in areas where no 1st and 2nd order soil surveys were performed. The aim of this study was to obtain a digital soil map (DSM) by artificial neural networks (ANN) using the correlation between soil mapping units and environmental covariates. The study area of approximately 11,000 ha is located in Barra Bonita, SP, Brazil. Based on a cluster analysis of environmental covariates, five reference areas were chosen for conventional […]

Soil surveys are the main source of spatial information on soils and have a range of different applications, mainly in agriculture. The continuity of this activity has however been severely compromised, mainly due to a lack of governmental funding. The purpose of this study was to evaluate the feasibility of two different classifiers (artificial neural networks and a maximum likelihood algorithm) in the prediction of soil classes in the northwest of the state of Rio de Janeiro. Terrain attributes such […]

Statistical modeling of spatial attributes aims to estimate dependence parameters, used to interpolate values at unsampled locations within the study area. Thus, the modeling process is conducted with some statistical criteria that ensure reliable predictions representing the actual local variability. This study evaluates different formulations of the Gaussian geostatistical model to reconstruct the surface of phosphorus over the area from the available measurements on 48 experimental plots located in Xanxerê/SC with emphasis on the methodological framework. Choices of covariates in […]

Digital information generates the possibility of a high degree of redundancy in the data available for fitting predictive models used for Digital Soil Mapping (DSM). Among these models, the Decision Tree (DT) technique has been increasingly applied due to its capacity of dealing with large datasets. The purpose of this study was to evaluate the impact of the data volume used to generate the DT models on the quality of soil maps. An area of 889.33 km² was chosen in […]

Seeds of common bean (Phaseolus vulgaris) with high molybdenum (Mo) concentration can supply Mo plant demands, but to date no studies have concomitantly evaluated the effects of Mo-enriched seeds on plants inoculated with rhizobia or treated with N fertilizer. This work evaluated the effects of seed Mo on growth and N acquisition of bean plants fertilized either by symbiotic N or mineral N, by measuring the activities of nitrogenase and nitrate reductase and the contribution of biological N2 fixation at […]

Pedotransfer functions (PTF) were developed to estimate the parameters (α, n, θr and θs) of the van Genuchten model (1980) to describe soil water retention curves. The data came from various sources, mainly from studies conducted by universities in Northeast Brazil, by the Brazilian Agricultural Research Corporation (Embrapa) and by a corporation for the development of the São Francisco and Parnaíba river basins (Codevasf), totaling 786 retention curves, which were divided into two data sets: 85 % for the development […]

Studies of soil-water dynamics using toposequences are essential to improve the understanding of soil-water-vegetation relationships. This study assessed the hydro-physical and morphological characteristics of soils of Atlantic Rainforest in the Parque Estadual de Carlos Botelho, state of São Paulo, Brazil. The study area of 10.24 ha (320 x 320 m) was covered by dense tropical rainforest (Atlantic Rainforest). Based on soil maps and topographic maps of the area, a representative transect of the soil in this plot was chosen and […]