LOW-COST ELECTRONIC WEIGHING LYSIMETERS

Evapotranspiration research lysimeters with 1 m2 area and 1.2 m depth were designed and constructed using commercially available cantilever load cells. These lysimeters were operated continuously for a three-year period at the Drainage Research Farm of Utah State University. Resolution of daily measurements of evapotranspiration (E(t)) from the fescue/forage grass mix was generally better than 0.05 mm or 1%. Accuracy of hourly measurements of E(t) was influenced by numerical resolution of the data logger and slight thermal instabilities within the load cells. Lysimeter measurements agreed well with E(t) estimated with the Penman-Monteith method. The total cost for a two-lysimeter installation including labor was $11,000. Maintenance and operation requirements were low.