EM38 Soil Conductivity Surveying

EM soil survey of a Canterbury river block

An EM Map is created by towing a non-invasive electircal conductivity sensor (Geonics EM38) over an area to create a map similar to that displayed on this page which shows relative spatial differences in soil conductivity.

The EM38 measures soil conductivity (EC), which is influenced by:

porosity/texture
moisture content
salinity (very few soils in New Zealand are influenced by this characteristic)
bulk density (eg, compaction)
other factors including Cation Exchange Capacity and temperature.

In New Zealand, most differences in EC that we see in maps generated by an EM Survey are the result of differences in soil type, moisture content and compaction. With local knowledge of particular areas and some ground-truthing, we can correlate an EM survey findings to other characteristics such as available water-holding capacity (AWC) which allows us to create prescriptions for variable rate irrigation scheduling.

For more information, please contact us using the form below.