A method for installing zero-tension pan and wick lysimeters in soil.

摘要

Zero-tension pan lysimeters and passive capillary fiberglass wick lysimeters are useful in determining water quality and volumetric aspects of subsurface water flow. A crucial aspect of installing pan and wick lysimeters beneath undisturbed soil is preventing cave-in of the tunnels in the soil that house the lysimeters. Equipment and a method were developed for installing zero-tension pan lysimeters and wick lysimeters in field plots, and this new method provides substantial structural strength of the tunnels. The dimensions of the upper horizontal surface of the pan lysimeters that were used were 0.280x0.430 m, and those of the wick lysimeters were 0.300x0.300 m, but the equipment can be modified to accommodate other lysimeter dimensions. The main equipment components are steel boxes which are pushed horizontally from a pit, into soil beneath the field plot, and a guiding frame that pushes the boxes using a hydraulic cylinder powered by a tractor hydraulic system. Following installation of each pair of steel boxes in soil, the soil from within the boxes was excavated, the upper lid of the lysimeter box was removed, and a lysimeter was placed within the box with the upper surface of the lysimeter directly contacting the soil. The equipment and method were used in the sandy loam soil of tall fescue (Fescue arundinacea Schreb.) pasture plots and the equipment and method worked well. The method also helps assure accurate lysimeter depth and levelness. The lysimeters were installed at a depth of 0.500 m beneath the soil surface. Costs and labor requirements for developing the equipment and using the method are presented. There was no evidence that the installation method altered the soil bulk density or the water flow paths above the lysimeters.