LOCATING SAMPLING SITES FOR SALINITY MAPPING

An evaluation of the suitability of a commercial long-range navigation (LORAN-C) method to locate and determine mapping coordinates of soil salinity sites was made in California field trials. The LORAN-C-determined position was within 16 m of the true position 90% of the time. This is sufficient accuracy to locate sampling areas identified with Systeme Probatoire d'Obervation de la Terre (SPOT) satellite imagery (pixel resolution of 30 m), but not for locating smaller sampling areas, such as those identified in low-altitude photographs. The LORAN-C method proved suitable for producing regional salinity maps that could resolve soil-salinity differences on a scale of 200 m.