IRRIGATION SCHEDULING IN THE CENTRAL REGION: MAKING EVERY DROP COUNT

LIMITED water supplies have a significant impact on sugarcane yields across the Australian sugarcane industry and, in particular, the Central region. Applying irrigation water at the right time, to maximise yield, is a difficult task and traditional irrigation scheduling tools provide little assistance. This paper reports how crop modelling was used to develop ‘best-bet’ irrigation guidelines for the Central region. These guidelines reduce the risk that irrigations will occur either too early or too late and, in doing so, increase the chance of maximising yields for a given allocation. The sugarcane crop model, WaterSense, was used to simulate twelve month old ratoon crops grown on three different soil types, with five irrigation allocations. Four climate zones were used to represent the geographical spread of the region. The modelling clearly shows that irrigators would improve yields if geographic locality and soil water holding capacity was taken into consideration when scheduling limited irrigation. The modelling also highlighted the yield penalty that could result if irrigators took a conservative approach to irrigating by saving irrigation water for a possible drought in the future. Best-bet guidelines have been developed for use in conjunction with the web-based irrigation scheduling crop model, WaterSense.