Lysimeters Support

Frequently asked questions:





Question 1: How deep can I install the lysimeters?




The dual chamber models can be installed at depths of up to several hundred meters (500 feet or more). The single chamber models should be installed no deeper than six meters (about 20 feet).




Question 2: Should I use a contact material to ensure good contact between the porous section of the lysimeter and the surrounding soil or sediment?




Many researchers use sifted fine sand removed from the depth of lysimeter installation as contact material. If such sand is not available, silica flour may be used as contact material. It is best to add water to the contact material first, resulting in a slurry that can be poured down a plastic pipe temporarily placed in the access hole.




Question 3: Are vacuum and pressure sources required for operation of the lysimeters?




Model SW-074 requires a vacuum source (i.e. a vacuum pump) to draw pore water from the surrounding medium into the lysimeter, and from there up into a collection bottle, located on the soil surface.


Model SW-071 can also be operated with just a vacuum source, if it is placed at a relatively shallow depth (i.e. less than 3 to 4 meter), and if a collection bottle is located on the soil surface, as for model SW-074.


However, SW-071 models are usually operated such that the pore water is collected in the lysimeter itself. In that case a pressure pump (hand pump or electric pump) is needed to apply pressure to the vacuum/pressure tube of the lysimeter. This forces the water from the lysimeter up into the collection bottle. A good bicycle can be used for this purpose.


The dual chamber models SW-070 and SW-070A need both vacuum (to draw the pore water into the lysimeter and into the upper chamber of the lysimeter), and pressure. Pressure is needed to force the pore water sample up through the fluid return tube to the collection bottle at the soil surface. For a lysimeter placed at a depth of 30 meters (98 feet) one needs an air pump that can deliver a pressure of at least 30 meters, equivalent to 3 bars or about 45 psi. Note that most bicycle pumps can deliver at least 100 psi or 6.6 bars.




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