YIELD REDUCTION DUE TO NON-UNIFORMITY OF TRAVELLING GUN IRRIGATORS

Previous trials both assessed the performance of travelling gun irrigators and identified how these systems could be fine-tuned to improve uniformity but did not quantify the associated increase in yield. This paper identifies the yield impacts due to non-uniformity of these irrigation systems in the Bundaberg area. Relationships between crop yield and water applied were developed from field tests. The crop water relationships developed were then applied to earlier test results to quantify the impact of uniformity on yield. An 8% reduction in yield was determined for a 10% reduction in uniformity (measured by Christiansen’s Uniformity Coefficient, CU). Previous work demonstrated increases in uniformity were possible under high wind conditions by changing from ring to tapered nozzles. This paper indicates that the measured increases in uniformity would have resulted in yield increases of approximately 15%.