Estimating ETO and scheduling crop irrigation using Blaney–Criddle equation when only air-temperature data are available and solving the issue of missing meteorological data in Egypt

Abstract

Accurate assessment of evapotranspiration is essential for crop irrigation planning. In developing countries and given the cost of evaluating evapotranspiration based on the Penman-Monteith equation, this research is an attempt to provide a simple equation that depends only on temperature to estimate evapotranspiration and serve as an alternative method to FAO56-PM when only air temperature data are available and the problem of missing meteorological data is solved. Four reference methods for evapotranspiration (ET) were compared under the local climatic conditions of the El-Nobaria region in northern Egypt. The Blaney–Criddle method was found to have the highest correlation with the FAO56-PM method. Using the simple equations to calculate ETo for irrigation scheduling of peanuts had a positive effect on the yield and yield components of peanuts. The highest productivity value was obtained when the Blaney–Criddle equation was used to estimate peanut irrigation scheduling, while equation resulted in lower productivity. When the equation was used, the differences in productivity between the equations were highly significant. It is worth noting that when the Blaney–Criddle and Thorthwaite equations were used, followed by the FAO56-PM equation, the superiority of the water productivity value became evident, as the increase in nutrient concentration in the root zone led to increased nutrient uptake, resulting in an increase in the productivity of peanut yield, oil and protein.