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Improving irrigation management by modelling the irrigation schedule

Abstract:

Three different treatments on corn, grown in Egyptian soil with shallow water table, on a cracked clay-loam soil subjected to swelling and shrinking, and in soil with a shallow water table have been evaluated using the simulation model SWATRE. With this field water balance model the in- and outgoing water fluxes, the soil moisture profile and the water-table depth of the three irrigation treatments monitored were simulated daily throughout the 1983 growing season. For validation the simulated water-table depths were compared to the observed water-table fluctuation. The validated field water balance model was then used to evaluate a number of hypothetical irrigation schedules in order to improve the actual irrigation practice. The simulation runs indicated that the water-table contribution through capillary rise varies between 25 and 30% of the actual crop water consumption, and that this amount is barely affected by the screened irrigation schedules. In addition it was found that plant transpiration and yield respond accurately to modifications in the irrigation timing applied. © 1988.