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| Registros recuperados: 31 | |
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| Seidel,Enio Júnior; Oliveira,Marcelo Silva de. |
| ABSTRACT: In geostatistical studies, spatial dependence can generally be described by means of the semivariogram or, in complementary form, with a single index followed by its categorization to classify the degree of such dependence. The objective of this study was to construct a categorization for the spatial dependence index (SDI) proposed by Seidel and Oliveira (2014) in order to classify spatial variability in terms of weak, moderate, and strong dependence. Theoretical values were constructed from different degrees of spatial dependence, which served as a basis for calculation of the SDI. In view of the form of distribution and SDI descriptive measures, we developed a categorization for posterior classification of spatial dependence, specific to each... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Geostatistics; Spatial dependence; Spatial variability; Semivariogram; Summary measures. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832016000100313 |
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| Vieira,Sidney Rosa; Paz Gonzalez,Antonio. |
| The objective of this study was to assess spatial variability of soil properties and crop yield under no tillage as a function of time, in two soil/climate conditions in São Paulo State, Brazil. The two sites measured approximately one hectare each and were cultivated with crop sequences which included corn, soybean, cotton, oats, black oats, wheat, rye, rice and green manure. Soil fertility, soil physical properties and crop yield were measured in a 10-m grid. The soils were a Dusky Red Latossol (Oxisol) and a Red Yellow Latossol (Ultisol). Soil sampling was performed in each field every two years after harvesting of the summer crop. Crop yield was measured at the end of each crop cycle, in 2 x 2.5 m sub plots. Data were analysed using semivariogram... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Spatial variability; Kriging; Yield map; Semivariogram. |
| Ano: 2003 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052003000100016 |
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| Lambert, Dayton M.; Florax, Raymond J.G.M.; Cho, Seong-Hoon. |
| This research note documents estimation procedures and results for an empirical investigation of the performance of the recently developed spatial, heteroskedasticity and autocorrelation consistent (HAC) covariance estimator calibrated with different kernel bandwidths. The empirical example is concerned with a hedonic price model for residential property values. The first bandwidth approach varies an a priori determined plug-in bandwidth criterion. The second method is a data driven cross-validation approach to determine the optimal neighborhood. The third approach uses a robust semivariogram to determine the range over which residuals are spatially correlated. Inference becomes more conservative as the plug-in bandwidth is increased. The data-driven... |
| Tipo: Working or Discussion Paper |
Palavras-chave: Spatial HAC; Semivariogram; Bandwidth; Hedonic model; Research Methods/ Statistical Methods; C13; C31; R21. |
| Ano: 2008 |
URL: http://purl.umn.edu/45964 |
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| Vendrusculo,Laurimar Gonçalves; Magalhães,Paulo Sérgio Graziano; Vieira,Sidney Rosa; Carvalho,José Ruy Porto de. |
| Geostatistics identifies the spatial structure of variables representing several phenomena and its use is becoming more intense in agricultural activities. This paper describes a computer program, based on Windows Interfaces (Borland Delphi), which performs spatial analyses of datasets through geostatistic tools: Classical statistical calculations, average, cross- and directional semivariograms, simple kriging estimates and jackknifing calculations. A published dataset of soil Carbon and Nitrogen was used to validate the system. The system was useful for the geostatistical analysis process, for the manipulation of the computational routines in a MS-DOS environment. The Windows development approach allowed the user to model the semivariogram graphically... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Spatial variability; Semivariogram; Software. |
| Ano: 2004 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162004000100017 |
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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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| Vázquez,Eva Vidal; Vieira,Sidney Rosa; De Maria,Isabella Clerici; González,Antonio Paz. |
| Surface roughness isinfluenced by type and intensity of soil tillage among other factors, and it changes considerably with rain. In microrelief studies the advantages of using indices such as the fractal dimension, D, and the crossover length, l, is that they allow the partition of the roughness characteristics into properties that depend purely on the scale and on a scale free component, respectively. On the other hand, some geostatistical parameters may provide different ways to understand soil surface variability not addressed with fractal parameters. Changes in fractal dimension and semivariogram parameters for surface roughness evolution were evaluated as a function of cumulative rainfall on Oxisol samples over six tillage treatments, namely, disc... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Oxisol; Tillage; Soil surface roughness; Semivariogram; Crossover length. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162010000100011 |
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| Grego,Célia Regina; Vieira,Sidney Rosa; Antonio,Aline Maria; Della Rosa,Simone Cristina. |
| Experiments in agriculture usually consider the topsoil properties to be uniform in space and, for this reason, often make inadequate use of the results. The objective of this study was to assess the variability for soil moisture content using geostatistical techniques. The experiment was carried out on a Rhodic Ferralsol (typic Haplorthox) in Campinas, SP, Brazil, in an area of 3.42 ha cultivated under the no tillage system, and the sampling was made in a grid of 102 points spaced 10 m x 20 m. Access tubes were inserted down to one meter at each evaluation point in order to measure soil moisture contents (cm³ cm-3) at depths of 30, 60 and 90 cm with a neutron moisture gauge. Samplings were made between the months of August and September of 2003 and in... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Neutron moisture gauge; Semivariogram; Spatial and temporal variability. |
| Ano: 2006 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162006000400005 |
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| Farias,Paulo R.S.; Roberto,Sérgio R.; Lopes,João R.S.; Perecin,Dilermando. |
| The spatial distribution of the three principal species of sharpshooter (Dilobopterus costalimai Young, Acrogonia sp. e Oncometopia facialis Signoret), vectors of Xylella fastidiosa causal agent of Citrus Variegated Chlorosis, was studied by using geostatistics. The evaluations were carried out in a commercial 'Pera' sweet orange (Citrus sinensis [L.] Osb.) grove budded on Rangpur lime (Citrus limonia Osb.) located at Bebedouro, São Paulo state, aiming to establish better means for vector and disease control. The sharpshooters were monitored using with 50 uniformly distributed 3" x 5" yellow sticky traps hanging down in branches at 1.5 m up to the ground, which were replaced monthly. Acrogonia sp. was the prevalent species sampled. The results were used to... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Citrus Variegated Chlorosis; Citrus sinensis; Semivariogram; Kriging. |
| Ano: 2004 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1519-566X2004000100004 |
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| Abreu,Paulo G. de; Dalla Costa,Osmar A.; Feddern,Vivian; Morés,Nelson; Coldebella,Arlei; Ramos,Clóvis M. C.. |
| ABSTRACT The purpose of this study was to evaluate the spatial variation of temperature, relative humidity and black globe humidity temperature (BGHT) index in growing-finishing swine facilities, with and without evaporative air cooler. The experiment was conducted in a 60 x 9 m facility containing 32 pens of 3.20 x 4.00 m each, divided into two sectors. The treatments were without evaporative air cooler (control) and with evaporative air cooler. Temperature and relative humidity data were collected weekly in two periods (morning and afternoon) at 32 different sampling points, encompassing the center of each pen and the outer perimeter of the facility. Animal performance variables were: feed intake, feed conversion, weight out of the nursery, slaughter... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Animal welfare; Spatial analyses; Environment conditions; Semivariogram. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662016001101014 |
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| Almeida,André Quintão de; Souza,Rodolfo Marcondes Silva; Loureiro,Diego Campana; Pereira,Donizete dos Reis; Cruz,Marcus Aurélio Soares; Vieira,Jodnes Sobreira. |
| Abstract: The objective of this work was to model the spatial dependence and to map the rainfall erosivity index (EI30) in the semiarid region of Brazil. Registers of monthly erosivity from 210 rainfall stations were used, with daily time series equal to or greater than 15 years. Based on the values of the EI30, a spatial dependence model was made by adjusting the semivariogram. From the semivariogram models, erosivity isoline maps were generated with a kriging interpolator. According to the historical data series, the maximum monthly average value of the EI30 was observed in March, and the annual value ranged from 1,439 to 5,864 MJ mm ha-1 per year, classified as low and moderate, respectively. The highest EI30 values were obtained in the northern and... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: EI30; Geostatistics; Northeastern Brazil; Semivariogram. |
| Ano: 2017 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2017000600371 |
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| Silva,Kátia Araújo da; Rodrigues,Marcos Sales; Moreira,Filipe Bernard Ramos; Lira,Aíris Layanne Ferreira; Lima,Augusto Miguel Nascimento; Cavalcante,Ítalo Herbert Lucena. |
| Abstract Soil sampling is a fundamental procedure in the decision making regarding the management of the soil, thus, a sampling plan should represent as accurately as possible the evaluated crop field. Therefore, the objectives of this study were to suggest a soil sampling approach and soil sampling point allocation using spatial analyses and compare to the classic statistic method in irrigated mango orchards in the Brazilian semi-arid region. The experiment was carried out in three commercial mango orchards located in the region of the São Francisco Valley, Brazil. Soil samples were collected in 0-0.2 m and 0.2-0.4 m depths following regular grids where the number of samples varied from 50 to 56. Soil texture, soil bulk density, soil total porosity,... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Geostatistics; Mangifera indica L; Semivariogram; Spatial dependence. |
| Ano: 2020 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-29452020000503003 |
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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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| Farias,Paulo R.S.; Barbosa,José C.; Busoli,Antonio C.; Overal,William L.; Miranda,Vicente S.; Ribeiro,Susane M.. |
| The fall armyworm, Spodoptera frugiperda (J.E. Smith), is one of the chief pests of maize in the Americas. The study of its spatial distribution is fundamental for designing correct control strategies, improving sampling methods, determining actual and potential crop losses, and adopting precise agricultural techniques. In São Paulo state, Brazil, a maize field was sampled at weekly intervals, from germination through harvest, for caterpillar densities, using quadrates. In each of 200 quadrates, 10 plants were sampled per week. Harvest weights were obtained in the field for each quadrate, and ear diameters and lengths were also sampled (15 ears per quadrate) and used to estimate potential productivity of the quadrate. Geostatistical analyses of caterpillar... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Zea mays; Fall armyworm; Semivariogram; Kriging. |
| Ano: 2008 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1519-566X2008000300012 |
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| Morales,Luis Alberto; Paz-Ferreiro,Jorge; Vieira,Sidney Rosa; Vázquez,Eva Vidal. |
| The aim of this study was to describe the effect of lime additions on the spatial variability of pH and Eh in a typic Plintacualf cultivated with rice, in Corrientes, Argentina. The 5.1 ha field was divided in three sub plots at which dolomitic lime additions were made at the rates zero, 625 kg ha-1 and 1250 kg ha-1. The soil was sampled at three stages: before sowing thus in aerobic conditions, and then two more times in anaerobiosis. Ninety-six samples per sub plot were taken on each of the three sampling stages on a grid of 11.9 x 20 m. Soil pH and Eh were measured by routine methods. The pH values increased, whereas Eh values decreased, following flooding. The coefficients of variation for pH was rather low during all the three studied periods.... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Semivariogram; Flooded field; Liming; Kriging. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052010000500008 |
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| SILVA,Camila Santos da; MENDONÇA,Bruno Araujo Furtado de; PEREIRA,Marcos Gervasio; ARAÚJO,Emanuel José Gomes de; CASTELLANI,Débora Christina. |
| ABSTRACT Geostatistics is a tool that can be used to produce maps with the distribution of nutrients essential for the development of plants. Therefore, the present study aimed to analyze the spatial variation in chemical attributes of soils under oil palm cultivation in agroforestry systems in the eastern Brazilian Amazon, and their spatial dependence pattern. Sixty spatially standardized and georeferenced soil samples were collected at each of three sampling sites (DU1, DU2, and DU3) at 0-20 cm depth. Evaluated soil chemical attributes were pH, Al3+, H+Al, K+, Ca2+, Mg2+, cation exchange capacity (CEC), P, and organic matter (OM). The spatial dependence of these variables was evaluated with a semivariogram analysis, adjusting three theoretical models... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Cokriging; Ordinary kriging; Semivariogram; Soil properties. |
| Ano: 2018 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59672018000400280 |
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| Registros recuperados: 31 | |
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