title: Using multivariate geostatistics to assess patterns of spatial dependence of apparent soil electrical conductivity and selected soil properties.
abstract: The apparent soil electrical conductivity (ECa) was continuously recorded in three successive dates using electromagnetic induction in horizontal (ECa-H) and vertical (ECa-V) dipole modes at a 6 ha plot located in Northwestern Spain. One of the ECa data sets was used to devise an optimized sampling scheme consisting of 40 points. Soil was sampled at the 0.0-0.3 m depth, in these 40 points, and analyzed for sand, silt, and clay content; gravimetric water content; and electrical conductivity of saturated soil paste. Coefficients of correlation between ECa and gravimetric soil water content (0.685 for ECa-V and 0.649 for ECa-H) were higher than those between ECa and clay content (ranging from 0.197 to 0.495, when different ECa recording dates were taken into account). Ordinary and universal kriging have been used to assess the patterns of spatial variability of the ECa data sets recorded at successive dates and the analyzed soil properties. Ordinary and universal cokriging methods have improved the estimation of gravimetric soil water content using the data of ECa as secondary variable with respect to the use of ordinary kriging.
authors.affiliation: Centro de Ciências Agrárias e Ambientais, Universidade Federal do Maranhão, BR-222, Km 04, s/n, Boa Vista, 65500-000 Chapadinha, MA, Brazil.
authors.forename: Glécio Machado
authors.initials: GM
authors.lastname: Siqueira
authors.affiliation: Departamento de Ingeniería Agroforestal, Escuela Politécnica Superior, Universidad de Santiago de Compostela, Campus Universitario, s/n, 27002 Lugo, Spain.
authors.forename: Jorge Dafonte
authors.initials: JD
authors.lastname: Dafonte
authors.affiliation: Departamento de Ingeniería Agroforestal, Escuela Politécnica Superior, Universidad de Santiago de Compostela, Campus Universitario, s/n, 27002 Lugo, Spain.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Valcárcel Armesto
authors.affiliation: Departamento de Engenharia Agrícola, Universidade Federal Rural de Pernambuco, Dois Irmãos, 52171-900 Recife, PE, Brazil.
authors.forename: Ênio Farias
authors.initials: ÊF
authors.lastname: França e Silva
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D000077215:Clay; D004553:Electric Conductivity; D012987:Soil / Q000737:chemistry*; D013030:Spain; D014867:Water / Q000737:chemistry*
chemical_list: D000538:Aluminum Silicates; D012987:Soil; D014867:Water; D000077215:Clay