ABSTRACT
Soil microbiology traditionally has been preoccupied with soil fertility related to agricultural practices. Prior to the 1970s, there were virtually no microbiologic studies that extended below the root zone of the plants. Beginning in the 1970s, there was an increasing awareness of subsurface contamination, caused by various waste-disposal or waste-management practices. At that time, considerable concern was also raised about the effects of contamination on groundwater quality, and this concern began to draw microbiologists toward studying subsurface environments. The microbiology of shallow aquifers became an active topic of investigation.
