Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: May 6, 2004
Publication Date: January 10, 2005
Citation: Corwin, D.L. 2005. Geospatial measurements of apparent soil electrical conductivity for characterizing soil spatial variability. Chap. 18. In: J. Alvarez-Benedi and R. Munoz-Carpena (eds.), Soil-Water-Solute Process Characterization. CRC Press, Boca Raton, FL. pp. 639-672. Interpretive Summary: Soil is extremely heterogeneous. The heterogeneity of soil is reflected in its spatial variability or change in physical and chemical properties over distance both horizontally and vertically. It is the extreme complexity of soil spatial variability that makes the study of soils so difficult. Soil spatial variability influences any soil-related issue at field and landscape scales including, to mention a few, the fate and movement of contaminants in soil, the quality or health of soil, and within-field variation in crop production, which is the focus of precision agriculture concerns. One of the most powerful and reliable tools for characterizing soil spatial variability is the mapping of apparent soil electrical conductivity (ECa). Maps of ECa can be used to direct soil sampling and the soil samples are analyzed for the chemical and physical properties of concern to establish maps of their spatial variability. From the maps of spatial variability landscape-scale problems can be tackled. It is the goal of this book chapter to provide an overview of the characterization of soil spatial variability using ECa-directed soil sampling for three different landscape-scale applications: (i) the modeling of soil pollutants, (ii) precision agriculture, and (iii) soil quality. Guidelines, methodology, and strengths and limitations are presented for characterizing spatial and temporal variation in soil physical and chemical properties using ECa-directed soil sampling.
Technical Abstract: The significance of soil spatial variability lies in the fact that it is a key component of any landscape-scale soil-related issue including solute transport in the vadose zone, site-specific crop management, and soil quality assessment, to mention a few. There are a variety of methods for potentially characterizing soil spatial variability, but, none of these approaches has been as extensively investigated as the use of apparent soil electrical conductivity (ECa). Since its early agricultural use for measuring soil salinity, the application of ECa has evolved into a widely accepted means of establishing the spatial variability of several soil physico-chemical properties that influence the ECa measurement. Geospatial measurements of ECa are well-suited for characterizing spatial variability for several reasons. Geospatial measurements of ECa are reliable, quick, and easy to take. The mobilization of ECa measurement equipment is easy and can be accomplished at a reasonable cost. Finally, and most importantly, ECa is influenced by a variety of soil properties for which the spatial variability of each could be potentially established. It is the goal of this chapter to provide an overview of the characterization of soil spatial variability using ECa-directed soil sampling for three different landscape-scale applications: (i) solute transport modeling in the vadose zone, (ii) site-specific crop management, and (iii) soil quality assessment. Guidelines, methodology, and strengths and limitations are presented for characterizing spatial and temporal variation in soil physico-chemical properties using ECa-directed soil sampling.