Soil salinity assessment using the EM38: Field operating instructions and data interpretation

Abstract

The Geonics EM38® is a portable instrument designed to take in situ field measurements of soil conductivity to about 1.5 m depth. If used correctly, the EM38 allows rapid, reliable estimates of soil salinity to be obtained from large areas without intensive soil sampling. The meter is very useful for delineating the extent and relative severity of saline areas. Although soil salinity has the dominant effect on the EM38 signal, other soil physical factors such as clay content, moisture content and temperature can affect the response. If the EM38 measurements are to be related to plant performance and used for detailed diagnostic purposes over a range of soil types, they must be calibrated with laboratory determined salinity measurements. This report describes the correct operating, surveying and calibration procedures for the EM38