FAO Penman-Monteith equation for reference evapotranspiration from missing data
Author
Carvalho,Luiz Gonsaga de
Evangelista,Adão Wagner Pego
Oliveira,Klerisson Milton Gontijo
Silva,Bruno Montoani
Alves,Marcelo de Carvalho
Júnior,Arionaldo de Sá
Miranda,Wezer Lismar
Abstract
The determination of the amount of water needed for crops is one of the main parameters for correct irrigation planning. In this context the FAO Penman-Monteith method (FAO-PM) has been recommended as the best for the reference evapotranspiration (ETo) estimates. However it is not always possible to have all the necessary data for its application; in this case, alternative criteria must be used for this estimation. In this study, the objective was to estimate ETo by the FAO-PM method with only the maximum and minimum temperature values, here called Simplified FAO-PM, and compare it to the standard method (FAO-PM) with all input data, for Lavras, Minas Gerais State, Brazil. It was observed that the alternative method has the tendency to overestimate the standard method, however, this approach is feasible to estimate ETo for irrigation scheduling in localities where not all input data required for FAO-PM is available.