Soil Salinity Assessment Using Electromagnetic Induction and Inversion Technique – A Case Study in Portugal

Soil salinization limits agricultural productivity and can ultimately cause desertification and land abandonment. Salinity mapping represents a good contribution to control soil salinization. Recent research is revolutionizing how soil information can be obtained quickly and cheaply. By using a state-of-the-art electromagnetic (EM) instrument and inversion techniques, it is possible now to generate high-resolution EM conductivity images and, in conjunction with soil sampling, to obtain quasi 2D and 3D maps of soil salinity. In this study EM surveys were conducted in four experimental plots located in Portugal, with different levels of salinity. EM models obtained from joint inversion of EM data, collected at different heights and orientations, shows good agreement with soil sample electrical conductivity of the saturation extract (ECe) in the study area. The significant correlation between EM models and ECe permits therefore a rapid characterization of the spatio-temporal variation of soil salinity, allowing to further predict salinization risk under different conditions.