This irrigation scheduling model uses a water balance approach to determine when to irrigate using a trickle irrigation system to apply the water. The model describes the flow of water entering a cube from the left side, filling ellipsoides until water reaches the center of the cube where water from the next emitter combines with the modeled emitter to cause downward flow of water to deep drainage.

The irrigation model applies water to maintain a predetermined soil moisture range within the crop root zone. Rainfall enters the cube as one dimensional flow. Transpiration is calculated using Penman’s equation and a crop curve based on growing-degree-days. Evaporation is calculated based on potential evaporation and a leaf area index function for stage-one evaporation and a time base function for stage-two evaporation. The model has not been tested against field data. Testing of the model should be completed before this model is used to schedule trickle irrigations on a production field.