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| Registros recuperados: 159 | |
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| Siqueira,Glécio Machado; Dafonte,Jorge Dafonte; González,Antonio Paz; Vázquez,Eva Vidal; Armesto,Monteserrat Valcarcel; Guedes Filho,Osvaldo. |
| ABSTRACT Soil sampling is an important stage of digital soil mapping. The objective of this study was to characterize the spatial design of soil sampling using soil apparent electrical conductivity (ECa) and its optimized spatial sampling. For the characterization, it was used the Spatial Simulated Annealing (SSA) technique, incorporated on the software SANOS 0.1, and the method of response surface sampling design on the software ESAP 2.35. The ECa was measured at 1,887 points in an area of 6 ha located in the northwestern region of Spain. The EM38-DD equipment (Geonics Limited 2005) was used at 2 depths: vertical dipole (1.5 m effective measurement depth) and horizontal dipole (0.75 m effective measurement depth). Semivariogram showed trend for ECa in... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Geostatistics; Semivariogram; Spatial variability; Optimization; Soil sampling. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052016000400459 |
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| Machado,Roriz Luciano; Ceddia,Marcos Bacis; Carvalho,Daniel Fonseca de; Cruz,Eleandro Silva da; Francelino,Marcio Rocha. |
| Knowledge of maximum daily rain and its return period in a region is an important tool to soil conservation, hydraulic engineering and preservation of road projects. The objective of this work was to evaluate the spatial variability of maximum annual daily rain considering different return periods, at the Rio de Janeiro State. The data set was composed by historical series of 119 rain gauges, for 36 years of observation. The return periods, estimated by Gumbel distribution, were 2, 5, 10, 25, 50 and 100 years. The spatial variability of the return periods was evaluated by semivariograms. All the return periods presented spatial dependence, with exponential and spherical model fitted to the experimental semivariograms. The parameters of the fitted... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Runoff; Extreme rainfall; Geostatistics; Kriging. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052010000500009 |
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| Chiba,Marcio Koiti; Vieira,Sidney Rosa; González,Antonio Paz; Dechen,Sonia Carmela Falci; Maria,Isabella Clerici de. |
| This study was carried out in order to assess the spatial variability of some soil properties after adoption of no tillage system (NTS). A 19,200 m² plot was marked with a 20 x 20 m spacing grid. Crop yield and soil attributes, at 0-0.2 m deep layer, were measured in 63 points in 1985, 1987 and 1988. The spatial variability was assessed by semivariogram calculation using geostatistics. Soil base saturation index (BS) was interpolated by kriging and also, using a bivariate geostatistical method, the collocated cokriging (CLCK) using terrain elevation as ancillary data. Although, the coefficient of variation (Cv) for soil organic matter content decreased from 1985 (20.4%) to 1988 (10.7%), its mean value increased 32% in the same period. The soil fertility in... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Geostatistics; Kriging; Cokriging. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052010000500005 |
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| Orjuela-Matta,Helber Milton; Rubiano Sanabria,Yolanda; Camacho-Tamayo,Jesus H. |
| Studies that involve soil attributes variability help the analysis of the behavior of hydrophysical attributes in space, to support the decision-making process within the conception of precision agriculture. The aim of the present paper was to characterize the spatial variability of the surface infiltration and its relation to some soil physical attributes. The sampling was done with a rectangular mesh of 64 points with perpendicular distances of 52 m x 45 m between sampling points. The attributes studied were bulk density, contents of sand, silt and clay, soil moisture, cumulative infiltration, basic infiltration, sorptivity, and saturated hydraulic conductivity (Ks). Data were analyzed using descriptive statistics and geostatistics, identifying the... |
| Tipo: Journal article |
Palavras-chave: Geostatistics; Hydraulic conductivity; Infiltration; Sorptivity. |
| Ano: 2012 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392012000300015 |
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| Camacho-Tamayo,Jesús H; Luengas,Carlos A; Leiva,Fabio R. |
| Growing demand for food exerts pressure on natural resources and may lead to the expansion of agricultural frontiers in developing countries. Most of this pressure appears in tropical zones, in native savannahs, with naturally infertile soils prone to degradation. Crop management in these regions is based on generalized estimates, leaving aside the inherent soil variability, leading to low production efficiency and high risk of environmental damage. This study aims at determining the spatial variability of some chemical properties, including organic carbon, pH, exchangeable acidity, exchangeable aluminum, P, Ca, Mg, K and Na for two Oxisols with different levels of agricultural intervention, in Puerto Lopez, Colombia, in order to identify guidelines for... |
| Tipo: Journal article |
Palavras-chave: Geostatistics; Kriging; Soil management; Precision agriculture; Kriging. |
| Ano: 2008 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392008000100005 |
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| Silva Cruz,Joedna; de Assis Júnior,Raimundo Nonato; Rocha Matias,Sammy Sidney; Camacho-Tamayo,Jesús Hernán. |
| Soil variability occurs due to natural and anthropogenic factors acting at various spatial and temporal scales. The purpose of this study was to evaluate the spatial variability as well as the relation of some chemical attributes using different statistical techniques. The study was conducted in the municipality of Maracanaú (CE, Brazil) in the commercial area of sugar cane in a typic Hapludalf. Soils were sampled in a 100 x 100 m grid every 10 m and at a depth between 0 and 20 cm for determination of exchangeable acidity, pH (KCl), Ca, Na, K, Mg, P, N, sum of bases, cationic exchange capacity, base saturation and organic matter. Data were subjected to analysis of descriptive statistics, multivariate analysis and geostatistics. Attributes showed low and... |
| Tipo: Journal article |
Palavras-chave: Geostatistics; Principal components; Cluster analysis. |
| Ano: 2011 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-16202011000100015 |
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| Nicolau,Rafaela F; Mercante,Erivelto; Maggi,Marcio F; de Souza,Eduardo G; Gasparin,Eloi. |
| The purpose of this study was to analyze the spatial variability of soil properties and productivity and the chemical and physical properties of oranges (Monte Parnaso variety) in their geographical quadrants. This experiment was conducted in a commercial orange orchard in the municipality of Nova Laranjeiras in the State of Paraná, Brazil. A GPS receiver and a total station were used to measure the spatial location of the fruit and to determine which quadrant they were located in. In this experiment, 13 trees were studied. Twelve fruits were evaluated in each geographical quadrant, and 156 fruits were considered. After harvest, the productivity was expressed as kg per quadrant (kg quadrant-1). Next, physical tests (equatorial diameter (EqD), total fruit... |
| Tipo: Journal article |
Palavras-chave: Citriculture; Geostatistics; Spatial variability. |
| Ano: 2014 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-16202014000300006 |
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| Santos,Eduardo Lucas Ensslin dos; Seidel,Enio Júnior; Pazini,Juliano de Bastos; Oliveira,Marcelo Silva de; Appel Neto,Edemar; Barbosa,Ismael Canabarro. |
| ABSTRACT: The main purpose of this article was to evaluate the behavior and relationship of the range and components of SDI (Spatial Dependence Index) in general and in function of field factors such as soil types, type of attribute and soil layers. This evaluation was based on real data collected in national journals. It was noticed that the parameter range, in general and for different field factors, presented asymmetric positive behavior. The components of the SDI showed approximately symmetrical behavior. The SDI can capture the range behavior more intensely (the spatial variability behavior in the horizontal direction of the semivariogram), and, in a less intense way, the behavior of the contribution and sill parameters (the spatial dependence... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Spatial dependence; Geostatistics; Semivariogram; Field factors. |
| Ano: 2018 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84782018000600252 |
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| Acerbi Júnior,Fausto Weimar; Silveira,Eduarda Martiniano de Oliveira; Mello,José Márcio de; Mello,Carlos Rogério de; Scolforo,José Roberto Soares. |
| The Normalized Difference Vegetation Index (NDVI) is often used to extract information from vegetated areas since it is directly related to vegetation parameters such as percent of ground cover, photosynthetic activity of the plant and leaf area index. The aim of this paper was to analyze the potencial of semivariograms generated from NDVI values to detect changes in vegetated areas, analyzing their behavior (shape) and derived metrics (range, sill and nugget). Semivariograms were generated from NDVI values derived from Landsat TM images of May 2010, June 2010 and July 2011. The study area is located in the northern state of Minas Gerais, Brazil, and is covered by Brazilian savannas vegetation, totalizing 1,596 ha. Semivariograms were generated after the... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Deforestation; Geostatistics; Remote sensing. |
| Ano: 2015 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-70542015000200103 |
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| Hurtado,Sandro Manuel Carmelino; Silva,Carlos Alberto; Resende,Álvaro Vilela de; Von Pinho,Renzo Garcia; Inácio,Euzelina dos Santos Borges; Higashikawa,Fábio Satoshi. |
| In Brazil, technicians, in most cases, ignore the aspects related to the spatial variability of the soil acidity attributes when liming requirement is calculated. The objective of this study was to validate the liming practice, evaluating the presence of spatial variability of the soil acidity attributes and the existence of areas with differentiated liming requirement, which were calculated by different methods. The experiment was carried out in an area cultivated with corn under conventional management and irrigation. The soil (0-0.2 m) was sampled in a conventional way (composite soil sample) and in a systematic scheme, by use of a grid sampling. In sequence to the soil fertility attributes analysis, it was calculated the liming requirement, according... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Precision agriculture; Geostatistics; Zea mays (L); Liming application zones. |
| Ano: 2009 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-70542009000500022 |
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| Batista,Pedro Velloso Gomes; Silva,Marx Leandro Naves; Avalos,Fabio Arnaldo Pomar; Oliveira,Marcelo Silva de; Menezes,Michele Duarte de; Curi,Nilton. |
| ABSTRACT Terrain models that represent riverbed topography are used for analyzing geomorphologic changes, calculating water storage capacity, and making hydrologic simulations. These models are generated by interpolating bathymetry points. River bathymetry is usually surveyed through cross-sections, which may lead to a sparse sampling pattern. Hybrid kriging methods, such as regression kriging (RK) and co-kriging (CK) employ the correlation with auxiliary predictors, as well as inter-variable correlation, to improve the predictions of the target variable. In this study, we use the orthogonal distance of a (x, y) point to the river centerline as a covariate for RK and CK. Given that riverbed elevation variability is abrupt transversely to the flow... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Geostatistics; Spatial prediction; Regression kriging; Riverbed morphology. |
| Ano: 2017 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-70542017000400402 |
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| Jaramillo-Barrios,Camilo Ignacio; Ortiz-Rico,Andrés Felipe; Carrillo,Gustavo Alfonso Araujo; Varón-Ramírez,Viviana Marcela. |
| ABSTRACT Soils have the ability to maintain plant growth and biological activity due to their physical and chemical properties. The aim of this study was to observe the spatial distribution of some chemical properties of the soil, such as pH, organic matter (OM), electrical conductivity (EC), effective cation exchange capacity (ECEC), sulfur (S) and aluminum (Al) content and to establish zones with homogeneous chemical characteristics using the MULTISPATI-PCA technique and the fuzzy c-means algorithm. The study area was located in the Tundama and Sugamuxi Valleys (Boyacá, Colombia) with an area of 8,017 ha. Chemical properties such as pH, OM, EC, S, Al, and ECEC were indicators of the chemical degradation of these soils. Four homogeneous zones were... |
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Palavras-chave: Geostatistics; Semivariogram; Soil degradation; Multispati-PCA; Spatial distribution.. |
| Ano: 2019 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-70542019000100216 |
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| Santos,Marcela de Castro Nunes; Mello,José Marcio de; Mello,Carlos Rogério de; Ávila,Léo Fernandes. |
| The spatial characterization of soil attributes is fundamental for the understanding of forest ecosystems. The objective of this work was to develop a geostatistical study of chemical and physical soil attributes at three depths (D1 - 0-20 cm; D2 - 20-50 cm; D3 - 50-100 cm), in an Experimental Hydrographic Micro-catchment entirely covered by Atlantic Forest, in the Mantiqueira Range region, Minas Gerais. All the considered variables presented spatial dependence structure in the three depths, and the largest degrees of spatial dependence were observed for pH in the three depths, soil cation exchange capacity potential in D3, soil organic matter in D1 and D3 and clay and soil bulk density in D2. The method most used for the adjustments of semi-variogram... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Brazilian native forest; Geostatistics; Soil features. |
| Ano: 2013 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-70542013000100008 |
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| Registros recuperados: 159 | |
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