DISE 1O Y FUNCIONAMIENTO DE UN LIS\ucdMETRO HIDR\uc1ULICO PARA MEDICI 3N DE LA EVAPOTRANSPIRACI 3N POTENCIAL

Un lis\uedmetro hidr\ue1ulico relativamente econ\uf3mico fue dise\uf1ado e instalado con el objeto de comprobar su funcionalidad para medir la evapotranspiraci\uf3n potencial (ETP). Tres tanques cil\uedndricos de 57 cm de di\ue1metro y 88 cm de altura se utilizaron como envases receptores de suelo; en ellos se sembr\uf3 pasto pangola (Digitaria swazilandesis) y debajo se colocaron sensores en forma de aro, conectados cada uno a un man\uf3metro de agua. Dos de los lis\uedmetros se usaron para medir evapotranspiraci\uf3n y al tercero se le interrumpi\uf3 la p\ue9rdida o ganancia de agua, con el fin de detectar las variaciones del nivel de agua en su man\uf3metro por el solo efecto de la temperatura y mediante estas variaciones, poder corregir las lecturas. La experiencia en el invernadero demostr\uf3 la buena estabilidad del lis\uedmetro, as\ued como tambi\ue9n su sencillez y f\ue1cil manejo. Los resultados obtenidos demostraron buena confiabilidad en las mediciones del aparato. Se encontr\uf3 un valor de 0,71 para la relaci\uf3n ETP/Evaporaci\uf3n medida en tina. ABSTRACT Design and performance of a hydraulic lysimeter for measurement of potential evapotranspiration A relatively economical hydraulic lysimeter was designed and installed in order to check its performance for measurement of potential evapotranspiration. Three 57 cm-diameter and 88 cm-height cylindrical tanks were used as receptor containers of soil. In these tanks, Swazi grass (Digitaria swazilandensis) was sown. Like-hoop sensors were put under the tanks and connected to water manometers. Two of the lysimeters were used to measure evapotranspiration. In the third one, the loss or gain of water was interrupted in order to detect variations of the water level in its manometer because of the unique temperature effect and these variations were used to correct the lysimeter readings. The glasshouse experience proved the good stability of the lysimeter which showed its simplicity and easy use. The results demonstrated the good reliance of the responses of the apparatus. A value of 0,71 was found for the relationship between ETP and pan evaporatio