Modelling the Irrigation Need

Abstract

On the basis of a model for daily calculation of the actual evapotranspiration and the water balance in the root zone, the irrigation need for grass and barley has been calculated in relation to root zone capacity and climatic conditions. The results show that the irrigation need is higher for grass than for barley. During the period 1956–85 four years have an extremely high irrigation need while in the mid-sixties there was a long period with a very low need. Curves showing the mean irrigation need in relation to root zone capacity have been elaborated. Furthermore, curves have been constructed combining irrigation need with root zone capacity and the frequency of years in which irrigation should be optimal.