Soil Water Balance: A Computer Tool for Teaching Future Irrigation Managers

Critical water shortage problems will face South Africa in the near future. It is extremely important to train future irrigation managers to apply new technologies to the solution of these problems. The Soil Water Balance (SWB) irrigation scheduling computer model was presented to 4th‐year agricultural students in the soil physics and irrigation courses at the University of Pretoria. The SWB model is a mechanistic, real time, user‐friendly model, that predicts crop growth and the soil water balance from available crop management, soil, and weather data. It includes a stand‐alone window in which the FAO (Food and Agricultural Organization) Penman‐Monteith grass reference evapotranspiration can be calculated (ET o calculator). The objectives were to assess the effectiveness of a computer application as a teaching tool, to determine whether a complex integrated model (SWB) is more suitable for educational purposes than a simpler model (ET o calculator), and to investigate the students' perception of the models. The exercise included a lecture where the theory was discussed, and the models were demonstrated making use of realistic examples. Optional homework exercises were then assigned and marked. The average score was 77.1% ± 8.0% for the SWB homework, and 80.8% ± 10.1% for the ET o calculator. The simpler ET o calculator appeared to be better understood than the more complex SWB. Several technical improvements were suggested by the students. Simple computer models are recommended for practical exercises at the end of each lecturing session. The demonstration of complex models integrating various lecturing sessions could then be made at the end of the course.