Measuring electromagnetic fields from an aeroplane is one way of tracking down accumulations of salt in the soil, and thereby mapping risks for agriculture.
Dr Richard Cresswell, who works at the Australian ministry of agriculture, and Dr David Dent of ISRIC used the data to construct a 3-D map of salt occurrence. They traced the salt deposits to a depth of 150 metres. To drill this deep would be very expensive and time-consuming. Nevertheless some field measurements of salt accumulations are necessary for calibration. Without these it is impossible to determine reliable absolute values for measuring salt quantities.
By combining these values and the 3-D map made from aerial measurements, the researchers say that a detailed salt-risk map can be drawn up for agriculture. This will help the government to implement more efficient measures. / HB