Correlation of EM38 and Veris apparent electrical conductivity to soil properties of agricultural fields

Authors: WODAJO, LETI - University Of Mississippi; Locke, Martin; Steinriede, Robert; MD ABDUS, SAMAD - University Of Mississippi; HICKEY, CRAIG - University Of Mississippi

Submitted to: Symposium on Application of Geophysics to Engineering and Environmental Problems Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 2/24/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: In agricultural fields, collecting and processing soil samples provide the most accurate data on soil properties. However, they are usually collected in a coarse grid, time-consuming to process, and could miss variabilities between sampling locations. On the other hand, geophysical measurements such as electromagnetic induction (EMI) surveys can be done at a much higher sampling rate and provide high-resolution spatial maps with detailed field variability. A better understanding of the correlation between geophysical and soil properties is required for an improved interpretation of geophysical results. In this study, apparent electrical conductivity (ECa) measurements were collected on an agricultural field using a Geonics EM38 and a Veris U series survey instruments. The study site in Sunflower, Mississippi, is part of United States Department of Agriculture Conservation Effects Assessment Project (CEAP) network, where soil physical properties were evaluated over multiple years. Correlation analysis was performed between apparent electrical conductivity (ECa) obtained from both survey methods and United States Department of Agricultures soil properties data (clay, water content, and soil electrical conductivity. A comparison of EM38 and Veris ECa maps showed that, while there are differences in the magnitude of the measured apparent electrical conductivity (ECa) values, the spatial distribution of apparent electrical conductivity (ECa) in the field is quite similar. Apparent electrical conductivity (ECa) measurements from EM38 and Veris showed good correlations with measured clay content. However, apparent electrical conductivity's (ECa) correlation with water content was low, probably because the soil water content and the survey assessments were done at different times and in different field conditions. Overall, this study showed that the application of rapid geophysical methods and establishing correlations with soil properties could lead to better soil and crop management decisions through the identification of farm field variability, improved soil sampling as opposed to grid-based soil sampling, and generating spatial variability maps of parameters relevant to plant growth (for example, clay content, soil salinity, soil texture, soil moisture).