The objective of this work was to test the "Irrigâmetro" to estimate the reference evapotranspiration in comparison to the Penman-Monteith method - FAO 56, and to compare its potential with the modified methods of Penman - FAO 24, Radiation - FAO 24, Class A Pan and Hargreaves-Samani (1985). The Irrigameter is an evapo-pluviometric apparatus recently developed at the Federal University of Viçosa to be used in irrigation water management. The reference evapotranspiration data obtained from the apparatus are compared with the data obtained from the method of Penman-Monteith, in intervals of one, three, five and seven days. According to the results, the Irrigameter presented satisfactory data to estimate ETo in all time intervals studied. Its low cost, high practicairty and inexistence of any additional calculations make it very suitable for irrigation water management in agriculture. The methods of modified Penman, Radiation and Hagreaves-Samani overestimated the ETo values obtained by the method of Penman-Monteith, while the Class A Pan presented the opposite behavior.
evaporation; evaporimeter; irrigation water management
