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| Siqueira,Glecio M.; Silva,Jucicléia S. da; Bezerra,Joel M.; Silva,Ênio F. de F. e; Dafonte,Jorge Dafonte; Melo,Ralini F. de. |
| A hipótese intrínseca é, normalmente, a mais utilizada por ser menos restritiva; quando comparada com as demais hipóteses da geoestatística exige apenas a existência de estacionariedade do semivariograma, sem nenhuma restrição quanto à existência de variância finita. O objetivo deste trabalho foi avaliar a estacionariedade de dados de umidade em um Espodossolo Humilúvico. Os dados foram coletados em um transeto contendo 128 pontos, espaçados a cada 3 m. O conteúdo de água no solo foi determinado nas camadas de 0,0-0,2 m, 0,2-0,4 m e 0,4-0,6 m. A análise estatística demonstrou que os dados apresentaram distribuição de frequência lognormal. Os valores de umidade variaram com as variações de relevo. Houve estacionariedade do semivariograma para as três... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Geoestatística; Física do solo; Amostragem do solo. |
| Ano: 2015 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662015000500439 |
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| Vázquez,Eva Vidal; Bertol,Ildegardis; Siqueira,Glécio Machado; Paz-Ferreiro,Jorge; Dafonte,Jorge Dafonte. |
| The objective of this work was to investigate the decay of initial surface roughness induced by simulated rainfall under different soil residue cover and to compare classical statistical indices with geostatistical parameters. A conventionally tilled loamy soil with low structure stability, thus prone to crusting was placed at 1 m² microplots. Each microplot received three successive rainfall events which bring about cumulative 25 mm, 50 mm and 75 mm at 65 mm h-1 intensity. Five treatments without replication were tested with different corn straw quantities (0, 1, 2, 3 and 4 Mg ha"1). Soil surface microrelief was measured at the initial stage and after each simulated rainfall event. Five treatments and four surface stages were monitored, resulting in 20... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Soil tillage; Roughness index; Surface microrelief; Simulated rain. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052010000500015 |
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| Dafonte,Jorge Dafonte; Guitián,Montserrat Ulloa; Paz-Ferreiro,Jorge; Siqueira,Glécio Machado; Vázquez,Eva Vidal. |
| Nutrient maps based on intensive soil sampling are useful to develop site-specific management practices. Geostatistical methods have been widely used to determine the spatial correlation and the range of spatial dependence at different sampling scales. If spatial dependence is detected, the modelled semivariograms can then be used to map the interested variable by kriging, an interpolation method that produces unbiased estimates with minimal estimation variance. The objectives of this paper were to examine and to map the spatial distribution of the micronutrients Cu, Zn, Fe and Mn on an agricultural area in Galicia, Spain, under European Atlantic climatic conditions. The ordinary kriging was first used to determine the values for the non-sampled locations,... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Soil management; Geostatistics; Spatial variability; Soil chemistry. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052010000500018 |
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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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