The gamma density probe is a useful instrument for measuring water content in small volumes of soil. Essentially, the gamma probe measures the density of the soil and water between a source and a detector. To transpose the gamma densities into water content, the dry bulk density of the soil is needed. A nondestructive method for estimating dry bulk densities for use with the gamma probe is proposed. The procedure is based on the assumption that water content values in a field dry condition were more stable than the dry bulk density values and could be transferred from one point to another. The procedure was successfully used on three areas in Reynolds Creek Experimental Watershed in Southwest Idaho.