Soil Compaction above Long-Term Lysimeter Installations

Equilibrium tension lysimeters are useful tools for monitoring soil water and solute fluxes. The potential residual effects of lysimeter installation procedures are unknown, however. During summer 2006, 12 lysimeters were excavated after long-term installation, and soil deformations above the lysimeters and installation materials were observed and documented. Bulk density of soil clods collected from above lysimeters and of clods confined in the lysimeters' pans increased 11 and 8%, respectively, between 1995 and 1999 (grouped together) and 2001 installations. This compaction probably introduced some increasing amount of error to water flux measurements as the installations aged, although this could not be assessed. Minor modifications to installation methods including supporting the soil at the front of the excavated cavity, increasing support spring length, and eliminating the use of soil slurry above the lysimeter's porous plate may reduce the potential for soil compaction above lysimeters and increase performance longevity in field installations.