What is a lysimeter?

By Marco Pena, UA Research Specialist

While sampling for whitefly at the University of Arizona Yuma Ag Center (YAC) I saw this huge block of soil suspended in a tank. When I asked what it was I was told a "lysimeter." Obviously my next question was what is a lysimeter?

A lysimeter is a device which can be used to measure the amount of evapotranspiration - the sum of evaporation and plant transpiration. By recording the amount of precipitation that an area receives and the amount lost through the soil and its vegetation, we can calculate the water lost by evapotranspiration.

There are two types of lysimeters: weighing and non-weighing.

YAC researchers are conducting projects with weighing lysimeters. A weighing lysimeter, which in this case is a big square tank with weight cells on each corner, shows the amount of water that crops use and the loss of water as vapor through stomata.

This is done by constantly weighing the block of soil in a field to detect losses of soil moisture. The crop, in this case cauliflower, is grown in the soil tank which allows the estimation of crop needs.

The rainfall input and water lost through the soil is also calculated. The data is constantly collected and automatically sent to the computers at the YAC. Also the relation between the weather and water usage by different crops is established using the AZMET weather stations.

Finally the water that infiltrates below the root system is collected, then pumped out of the tank, and analyzed for various elements.

For more information, contact Charles Sanchez at the YAC at (928)782-3836 or sanchez@ag.arizona.edu.

Contact Pena: (928)782-3836 or marcop@ag.arizona.edu