Ground conductivity meters are used in a number of precision agriculture applications, including the estimation of water content, nutrient levels, salinity and depth of topsoil. Typically the Geonics EM38 conductivity meter, and to a lesser extent the EM31, are used for soil surveys. Most conductivity surveys involve towing a ground conductivity meter behind an all-terrain vehicle (ATV). In some situations, such as rutted or sloping fields, it is preferable to mount the conductivity meter directly to the ATV. In this case the conductivity meter must be attached to the ATV in such a way that interference from the metal in the ATV is minimal.

In some cases a soil survey requires collecting data from two conductivity meters, each of which has a different depth of penetration. Attaching both instruments to the ATV, and carrying out the survey in one pass, can substantially reduce survey time and expense.

In order to carry out such a survey, not only must the interference from the ATV be minimal, but the two instruments must not interfere with one another. We have developed methods that allow us to use booms to attach, with minimal interference, an EM38 and EM31 to an ATV. We have also developed interference correction methods to remove residual interference from the ATV on both the EM38 and EM31 instruments. In addition, we have measured the interference effects of the EM38 and EM31 on each other, and determined inter-instrument spacing and transmitter-receiver orientations that reduce mutual interference to a low level. These techniques allow us to attach one or both instruments to an ATV and survey a field in a single pass.