Mapping soil heterogeneity using spatially constrained inversion of electromagnetic induction data

Precision agriculture applications rely on highly detailed information on variations in soil properties. This demand has led to recent developments in EMI instrumentation, resulting in stable and high data quality. The reliability of the data enables real non-linear inversion providing true formation resistivity with depth. With the aim of mapping soil heterogeneity, an EMI survey has been carried out in the central part of Jutland, Denmark. The collected data were carefully processed prior to inversion in order to remove any couplings from man-made conductors such as buried electrical cables, which can cause errors in the lithological interpretation. The data were subsequently modelled with a 1D layered spatially constrained inversion which takes the entire EMI data geometry into account. The inversion results gives a detailed quasi tree-dimensional image of the survey area, revealing several small scale resistivity variations which corresponds well with existing geological knowledge.