U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


Date of this Version



Geoderma 223–225 (2014) 33–45; http://dx.doi.org/10.1016/j.geoderma.2014.01.027


U.S. Government Work


Electromagnetic induction (EMI) has been used to characterize the spatial variability of soil properties since the late 1970s. Initially used to assess soil salinity, the use of EMI in soil studies has expanded to include:mapping soil types; characterizing soil water content and flow patterns; assessing variations in soil texture, compaction, organicmatter content, and pH; and determining the depth to subsurface horizons, stratigraphic layers or bedrock, among other uses. In all cases the soil property being investigatedmust influence soil apparent electrical conductivity (ECa) either directly or indirectly for EMI techniques to be effective. An increasing number and diversity of EMI sensors have been developed in response to users' needs and the availability of allied technologies, which have greatly improved the functionality of these tools. EMI investigations provide several benefits for soil studies. The large amount of georeferenced data that can be rapidly and inexpensively collected with EMI providesmore complete characterization of the spatial variations in soil properties than traditional sampling techniques. In addition, compared to traditional soil survey methods, EMI can more effectively characterize diffuse soil boundaries and identify areas of dissimilar soilswithin mapped soil units, giving soil scientists greater confidencewhen collecting spatial soil information. EMI techniques do have limitations; results are site-specific and can vary depending on the complex interactions amongmultiple and variable soil properties. Despite this,EMI techniques are increasingly being used to investigate the spatial variability of soil properties at field and landscape scales.