EM38

The EM (electormagnetic meter) is used to measure the conductivity of the soil. The device is equipped with two coils. The emitting coil generates a magnetic field which is transmitted into the subsoil. In response the earth emits a second magnetic field. This reaction is measured by the second coil. The difference between the first and the second  magnetic field gives information about the conductivity (or resistance) of the soil.

From this data the variation in soil properties can be determined, for example moisture content, salinity and porosity. The EM is also used in conducting archeological and geological research.