Farmer and agronomist knowledge
Farmers and agronomists have a wealth of knowledge about their fields. This can provide key information regarding why a soil type behaves as it does. For example, two identical soil types within a field can yield completely differently.
Those managing the farm may already know why.
Ground truthing
Obtaining a soil sample from a high and low millisiemens area will provide an exact soil type that provides an accurate indication of soil type across the field. In the example within the electronic data above, the lightest areas of the field are sandy clay loam and the darkest are clay loam. This data can be used to compare fields across the farm rather than just variation within the field (additional cost).
EM management zones decided:
These zones are created using some or all the following - soil type contour, raw variation data and elevation data.