Fact Sheet #23 – February 2007
Rick Llewellyn – CSIRO Sustainable Ecosystems, Ben Jones – Mallee Focus,
Garry O’Leary – DPI Horsham Vic., David Roget – CSIRO Sustainable Ecosystems
Most Mallee growers are now aware of electromagnetic induction technology (EM) as a potential tool for mapping variation in soil across paddocks and farms. Many growers are looking to make use of EM-based maps as part of the shift to better targeting of inputs to zones within paddocks based on yield potential.
EM38 measures soil electrical conductivity of water in the soil and the soil itself, which is influenced by the soil salt and water content, and the amount and type of clay in the soil. It can help to identify where important subsoil constraints may be present in Mallee paddocks and in assessing variation in the amount of soil water that can be available to plants.
Largely because of the saline geological history and dune systems of the Mallee landscape, relatively high correlations are usually found across a paddock between EM measurements and soil characteristics that are known to be important for Mallee crops such as subsoil salt, boron, texture and plant unavailable water.
It needs to be recognised that the EM responds to a combination of soil water, salinity, texture and temperature in varying proportions. Correlation with one characteristic can be poor and interpretation is not always simple.
This farmtalk uses results from over 30 paddocks across the Vic., SA and NSW Mallee to:
• Give a guide to how reliably EM mapping captures the soil waterrelated characteristics of most interest to growers.
• Look at what this means for getting most value from EM information in the Mallee environment.