Monitoring Soil Volumes

With respect to the previous post "Handling bacterial and genomic diversity", I have devised an experiment: drill a hole in the soil; put sterile sand in the hole; wait a fixed length of time; do a spectral analysis of the sand before and after.This determines which chemicals have leached into the sand over that time frame - the byproducts of organisms living around the hole.
One person with a mass spectrometer and a microscope could do a lot. Or, instead of spectrum, you could culture the sand as a way of monitoring. They must do this somewhere.
Update: or some kind of probe could be used to take a core sample from living tissue.