Magnetic Susceptibility in Topsoils and Bulk Cores of Cultivated Calcisols

The magnetic susceptibility (MS) in soils is a fast and non-destructive technique that can be used to infer the concentration of magnetic minerals. The objective of this study was to analyze MS on topsoil and bulk core samples of cultivated Calcisols. Magnetic susceptibility was measured at two different frequencies to assess the variation of magnetic susceptibility when the frequency of the applied magnetic field changed. The low frequency values of mass-specific MS ranged between 16.0 and 57.6 ×10 m kg. High correlation coefficients were found between the MS in topsoil and bulk core samples (r = 0.94). In addition, magnetic susceptibility was measured in situ in the field to compare with the results obtained in the laboratory. The measurements of MS in the field varied from 10.0 to 48.0 ×10 SI. High correlation coefficients were found between MS in laboratory and field measurements (r = 0.88). The methodology applied in this study using a susceptibility meter and a dual frequency sensor for the laboratory measurements and a probe handle for the field measurements has proved to be useful for fast and reliable measurements of MS in the field.