Trees act as minidrills with their root structures sampling very large volumes of soil and in the case of phreatophytes the root structure searches out the water table and may extend hundreds of metres below the surface.

Generally in the case of humus (decaying surface vegetation) the material is dried below 60oC and then macerated in a cutting mill with a 1 mm internal sieve. The ground material can be compressed into a briquette for neutron activation or ashed and analyzed by digestion and ICP or ICP-MS. Vegetation can also be dried and ground in a cutting mill to homogenize it. Subsequently it can be analyzed by compressing into a briquette by ashingand analysis of the ash. The choice of package depends on the elements and detection limits required. The ground vegetation can also be analyzed directly by digestion and analysis by High Resolution ICP-MS or by ICP-MS