Can APSIM be used by advisory staff at a local level?: a case study of irrigation in the Proserpine area

Despite validation by a number of workers in the Australian sugar industry, crop simulation tools have not been widely adopted by industry advisors. This paper aims to demonstrate that local advisory staff could employ the production system model, APSIM (Agricultural Production Systems SiMulator) to explore a number of irrigation attributes. APSIM was configured to determine effective rainfall, crop irrigation demand, crop response to irrigation and cane water index for different soil types and irrigation allocations in the Proserpine area. Crop simulations were conducted for a 40-year period between 1957 and 1997 from composite climate data collected at the Proserpine Post Office and Proserpine Airport. Results demonstrate that effective rainfall varied between 400 mm and 1200 mm depending on year and soil type. Irrigation was also shown to significantly reduce effective rainfall. The average irrigation demand for sugarcane in the Proserpine area was estimated to be between 4 and 6 ML/ha. However, this was sensitive to soil type and the Southern Oscillation Index (SOl) rainfall regime. Average crop response from the first two megalitres per hectare allocation was 13.5 t/ha, which decreased with each additional 2 ML/ha allocation. Cane Water Index (CWI) benchmarks determined at 100% irrigation application efficiency varied between years, soil type and allocation. Results demonstrate that APSIM was able to estimate credible values for district average and yearly variation in crop response to irrigation, water use efficiency, irrigation demand and effective rainfall. The study concluded APSIM was a useful tool that could be used by local advisory staff to assist in the planning and operation of irrigation systems.