An EM survey highlights the variability in soil type, this variability is then ground truthed by soil coring and lab analysis of the soil cores. In this example a strong correlation between increasing conductivity and soil pH exists in both the top soil 0-10cm and the mid soil 10-30cm. Traditionally a lime application on this farm would have involved the whole farm having a standard application rate of 1T/ha, however through an EM survey and soil coring only 124 hectares out of 324 hectares or 38% requires lime. Radiometrics is also providing good correlations to soil pH and we often use the Potassium, Thorium and Total Count maps to create variable rate lime prescriptions.
Zone map for variable rate lime application where the 1T/ha rate is targeting areas with acidic top soil, whilst the 1.5T/ha rate is targeting areas of acidic top soil and mid soil.