Methods of characterizing subsurface conditions in a selected geographic region previously associated as a whole with a specific subsurface material characteristic reference profile such as from a USDA-NRCS soil survey. The method includes deploying a sensing tool at selected positions within the geographic region to determine a depth-referenced subsurface material characteristic such as soil type or strata, comparing the determined subsurface material characteristic to the subsurface material characteristic reference profile associated with the geographic region to determine a correlation between the subsurface material characteristic reference profile and the depth-referenced subsurface material characteristic, and then deciding whether to deploy the tool at another position, and at what optimum position to deploy the tool, by considering the correlation.