Journal of Agricultural Meteorology

Journal of Agricultural Meteorology

Evaluation of reference evapotranspiration calculation methods and determination of Pistachio evapotranspiration in Rafsanjan

Authors
H. Noory
A. Badiehneshin
A. Mohammadi Mohammad Abadi
Abstract
The aim of this study was determination of Pestachio evapotrspitaion in Rafsanjan plain, south of Iran. For this purpose, the results of the six reference evapotranspiration (ETo) estimation equations was compared by ETo grass lysimetric measurements. Among the selected methods, Penman-Monteith FAO was found to be the best one with root mean square error (RMSE) of 1.3 mm.mm-1 and percent absolute error (PAE) equals to 17%, Kimberly-Penman, radiation and Blaney-Criddle methods were ranked next to PM equation with acceptable accuracy. Hargreaves and modified Penman method showed poor performance. Pistachio crop evapotranspiration (ETc) was determined using pistachio crop coefficients and 4 years average of lysimeteric values ETo. Based on the results, the mean Pistachio ETc was 9600 cubic meters per hectare during April to November during. Maximum of ETo and ETc occurred in July. More than 50% of ETc was observed in June, July and August which confirms the importance of maintaining sufficient water for irrigation during this period.
Keywords
Lysimeter
FAO Penman-Monteith
Pistachio
Water requirement