Determination of Irrigation Depths using a Numerical Model and Weather Forecast

Abstract

Effect of a scheme of determining irrigation depth using numerical simulation for crop response to irrigation and weather forecast was tested for wheat cultivation in the semi-arid region of Jordan. Drip irrigation system, a monitoring system for change in soil water content, and three different treatments (numerically optimized irrigation with this methodology, automated irrigation using solenoid valve, and rainfed) were prepared for the field experiment. Results showed that incomes of the irrigated-treatments predominated over that of the rainfed, while net incomes of the irrigated-treatments were smaller than that of the rainfed. The discrepancy between the numerically simulated soil water content and the measured one appeared, that is, the numerical simulation model overestimated the change in actual soil water content. Both of the decreases in the net income of the numerically optimized irrigation and the overestimated soil water content would result from the underestimated plant properties (drought tolerance, root zone depth) included in the input parameters of the numerical simulation.