A method for performing exploration of the vadose soil zone first obtains samples of the surface vegetation from a region, next the samples are analyzed to determine if a contaminant is present in any of the analyzed samples, and, finally, a determination is made if a vadose soil zone at that region is contaminated based on the analyzed samples. As a result of the contamination determination, further, more-detailed site characterization can be performed at only those regions that are contaminated.