Siqueira Glécio Machado, Dafonte Jorge Dafonte, Valcárcel Armesto Montserrat, França e Silva Ênio Farias
Centro de Ciências Agrárias e Ambientais, Universidade Federal do Maranhão, BR-222, Km 04, s/n, Boa Vista, 65500-000 Chapadinha, MA, Brazil.
Departamento de Ingeniería Agroforestal, Escuela Politécnica Superior, Universidad de Santiago de Compostela, Campus Universitario, s/n, 27002 Lugo, Spain.
ScientificWorldJournal. 2014;2014:712403. doi: 10.1155/2014/712403. Epub 2014 Dec 31.
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.
在西班牙西北部一块6公顷的地块上，使用电磁感应以水平（ECa-H）和垂直（ECa-V）偶极模式连续三天记录表观土壤电导率（ECa）。其中一组ECa数据集用于设计一个由40个点组成的优化采样方案。在这40个点的0.0 - 0.3米深度处采集土壤样本，分析其砂、粉砂和黏土含量、重量含水量以及饱和土壤糊的电导率。ECa与重量土壤含水量之间的相关系数（ECa-V为0.685，ECa-H为0.649）高于ECa与黏土含量之间的相关系数（考虑不同的ECa记录日期时，范围为0.197至0.495）。普通克里金法和泛克里金法已用于评估连续日期记录的ECa数据集以及分析的土壤性质的空间变异性模式。相对于使用普通克里金法，普通协同克里金法和泛协同克里金法使用ECa数据作为辅助变量改进了重量土壤含水量的估计。
