The objective of this work was to construct, install, calibrate and evaluate a weighing lysimeter with load cell, in order to estimate reference evapotranspiration (ETo) for the Seropédica region - RJ. The lysimeter, which has the dimensions of 1.0 m x 1.0 m and 0.7 m in depth, was built with galvanized steel and installed over a metallic structure mounted over transversal bars, in order to concentrate all the assembly mass over a load cell localized in the center of the system. The lysimeter was filled with the same soil layers of the local soil. Then a calibration was carried out by means of a linear regression analysis and the whole lysimeter area was planted with Bahia grass. The lysimeter system demonstrated to be suitable for estimating ETo, yielding a standard error of the linear regression of 0.278 kg or 0.278 mm. In addition, it displayed satisfactorily the variation of the main meteorological elements that influence in ETo.
evapotranspiration; lysimeter; load cell
