Lysimeters are a method used to study percolation and leaching losses of soil.  One type is called a plate lysimeter where water first moves down through undisturbed soil, then through sand and gravel on an inclined slope and goes into a collection container.  This leachate is finally pumped to a collection vesicle.  We use a second type of called suction lysimeters.  These suction lysimeters have an advantage over tile-drain systems found with plate lysimeters in that variations in a large area or field are avoided and numerous lysimeters can be used in a controlled experiment in which different soil-plant management systems are compared.  In our case we are able to compare ferilized with unfertilized second growth forest soils at different depths.  Our shallowest lysimeter is a simple pan that collects water after passing through the canopy and the forest floor.  It is generally only a few centimeters below the forest floor surface (Brady and Weill 2002).  

The other lysimeters are deeper and suction (also called negative tension) lysimeters that collect water from 15 cm to 1 m depths.  To investigate the soil and to install lysimeters we first dig a 0.25 meter squared pit (Figure 1).  Soil Weights of soils are determined at different depths as the soil is removed from the cubed pit (Figure 2).  A borer is used to core holes into the sides of the pits and then PVC tubes with porous cups attached are inserted into the cored holes and backfilled with native, sieved (25mm) soil.  

Figure 1


Figure 2                                                              

Figure 3