History of Lysimeter Design and Use for Evapotranspiration Measurements

Abstract

Lysimeters are devices for measuring percolation of water through soils and sampling soil water for chemical analyses. Lysimeters have been used for over 300 years to determine water use by vegetation. Precision lysimetry for measuring evapotranspiration (ET) has developed mainly within the past 50 years. Weighing lysimeter designs are quite varied to suite individual research requirements. Surface areas from 1.0 m 2 to over 29 m 2 have been used. ET accuracy depends directly on the lysimeter area, mass, and the type of scale, but many lysimeters have accuracies better than 0.05 mm. Few weighing lysimeters exceed 2.5-m profile depth. Mechanical, floating, hydraulic, and electronic scales have been used in weighing lysimeters with varying types of data recording methods. Lysimeter wall construction can affect heat transfer to the lysimeter and water flow along the walls. ET accuracy of weighing lysimeters can be affected by many additional factors (personnel traffic, cultural operations, crop height, etc.).