ABSTRACT

Abstract A model using weather forecast for predicting short-term supplementary irrigation demand is described. The model was applied in simulating potato irrigation under UK conditions at three levels of irrigation costs each for a dry year, wet year and average year. The results were compared with the case of scheduling to maintain acceptable level of soil water deficit without the benefit of weather forecast and with the case of no irrigation. The efficiencies of irrigation water use in terms of profit and yield per ha mm of irrigation were higher for irrigation with weather forecasts than without in the wet year at all the irrigation cost levels (1 ha mm = 0.01M1 ). The efficiencies were comparable at each level of irrigation cost for the average year and at the highest irrigation cost for the dry year. It was therefore concluded that short-term weather forecast can be used to improve the management of supplementary irrigation in wet years and in situations of high irrigation cost or water scarcity. Keywords: Demand management, supplementary irrigation, weather forecasting .