Evaluating the performance of automated bay irrigation

Previous evaluations of bay (or border check) irrigation in northern Victoria have shown that higher irrigation flows offer very much improved (volumetric) application efficiencies, well above those currently achieved. However, having the correct irrigation duration (or time to cut-off) is critical in reaching those efficiencies. Automation of bay irrigation provides the needed precision in managing the shorter irrigation durations that result from the higher flows. Hence, the objective of the study was to demonstrate the application efficiencies achievable through the use of automated, high-flow bay irrigation. Nine existing automated farms were selected for the trial that together represent the range of soils, bay geometries, irrigation management, and crops typical of the region. A total of 46 irrigations across the various sites were evaluated. Analysis of each event included calibration of the surface irrigation hydraulic simulation model SISCO from the measured flow rate, advance and depth data, and simulation of each event using SISCO to give the required performance parameters. The results from the evaluations demonstrate that application efficiencies in excess of 90 % are indeed achievable and being achieved through correct and precise management of automated surface irrigation. The prime reason for lower efficiency on some farms was incorrect choice of irrigation duration, resulting in significant losses to tail-water run-off. For those farms, strategies to improve performance have been suggested.