Background to EMI Scanning
EMI soil scanners are towed behind a quadbike or tractor and uses electromagnetic fields to measure soil's apparent electrical conductivity (ECa) at three different depths in the soil. By mapping the changes in soils ECa we can identify where changes in soil properties occur. Soil ECa is influenced by soil texture, water content, rock content and the presence of salts.
EMI Soil Scanning Applications
By mapping soil ECa we can reduce the number of soil profiles needed for a soil profiling investigations. Furthermore precise boundaries of soil variation can by made for precision fertilizer and irrigation design.
This map can be used for the lifetime of the crop for VRA fertilizer programs.
The instrument is set to measure every 0.2 seconds at three depths (0.25 m, 0,5 m and 0,9 m) while driving in a grid of between 5 to 10 meters to create a high resolutions soil variation maps.
The images below show the three measurement depths, with a sandier area at the Southern tip increasing with depth as well as each old termite heap in the Northern side of the
Problem Area Investigations
Combining soil EMI and crop surveys like drone or satellite imagery we can perform statistical analysis on problem areas to identify if your soil variation is the driver behind weaker areas in crop productivity.
This helps producers decide on the most effective way to deal with the problem areas identified and improve yield and quality.
Crop Vigour Map
Soil ECa Map
In this example the higher ECa measurements indicate weaker growth possibly indicating either too wet or compact soil growing conditions.
New Area Development
For large new investigation areas, EMI soil scanning can be used to identify soil variation and possible soil limiting layers. This helps planning of survey investigations to be as efficient as possible and helps your farm to have an optimised layout.
As two of the major driving major driving forces behind the EMI measurements are soil texture and soil water content, EMI surveys are thus the perfect tool for soil moisture probe placement.