نبذة مختصرة : The frequency domain electromagnetic induction (FDEM) method is a widely used tool for geophysical soil exploration. Field surveys using FDEM provide apparent electrical conductivity (ECa), which is typically used for qualitative interpretations. Quantitative estimations of soil properties remain challenging, especially in heterogeneous fields. Quantitative approaches are based on either deterministic or empirical modeling. While the deterministic approach faces limitations related to instrumental drift, data calibration, inversion, and pedophysical modeling, the empirical approach requires developing a local model, which involves extensive field sampling. This study aims to evaluate the effectiveness of FDEM modeling based on either a deterministic or empirical approach, identify its limitations, and search for optimal field protocols. We provide practical guidelines for end users to quantitatively predict soil water content, bulk density, clay content, cation exchange capacity, and water EC in heterogeneous fields. Two field surveys were conducted in Belgium, where FDEM data were collected using Dualem-421S and Dualem-21HS sensors, along with data taken from electrical resistivity tomography (ERT) measurements and an impedance moisture probe and soil sampling. A comprehensive sensitivity analysis revealed that deterministic modeling procedures could not predict water content more accurately than a mean value approximation (negative R2). This analysis also highlighted the sensitivity of the minimization method used in FDEM data inversion and the applied pedophysical model. Empirical modeling, which does not require FDEM data calibration or inversion, outperformed the deterministic approach. However, its prediction accuracy is limited, particularly if soil sample depth is not considered.
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