As the irrigation season ramps up across Tasmania, researchers at the Tasmanian Institute of Agriculture (TIA) are preparing to measure exactly what happens to water on irrigated soils - how much goes in and how much runs off.
Dr Ana Avila has recently joined TIA working on the $1.6 million Growing Value from Irrigation for Tasmanian Agriculture project, funded by the Tasmanian Government through the Agricultural Innovation Fund. Her research will focus on water losses from run-off and deep drainage in the outer spans of pivot irrigators, helping farmers improve pivot design and irrigation scheduling.
The research team is working closely with Tasmanian Irrigation, which manages 19 schemes statewide. These schemes have transformed farming regions into high-value production areas thanks to high reliability irrigation water.
"We are addressing a key knowledge gap in irrigation science. Despite decades of research there is still no clear quantification of the real effectiveness of centre-pivot irrigation systems in the field," Dr Avila said.
"Our aim is to measure how much of the applied water actually infiltrates and remains available to plants in the root zone, rather than being lost through run-off, evaporation, or deep drainage."
With a PhD in soil science and expertise in soil physics, Dr Avila is well placed to investigate how soils respond when shifting from dryland to irrigated farming. While it's well known that large pivot irrigators can experience run-off, leading to bogging, nutrient loss, and reduced crop growth, the actual volume of water lost remains unclear.
"Measurements will combine field data, using catch-cans, runoff meters, soil-moisture probes and infiltration tests, with modelling tools to analyse water balance efficiency and effectiveness," Dr Avila said.
Dr Avila has been refining research methods at the University of Tasmania Farm at Cambridge in southern Tasmania and will soon begin trials across Tasmania. Her team will also explore how soil variability, particularly in duplex soils, affects irrigation performance. Five case study sites will be established in 2026–2027 across major growing regions to demonstrate these impacts.
Beyond the field trials, the project is also assessing the economic benefits of irrigation investment. Associate Professor Dan Daugaard from the Tasmanian School of Business and Economics has been leading this work, which will inform practical irrigation management scenarios to support on-farm decision-making.
"The soil research trials link to the economic investigations by translating measured water losses into financial terms, by establishing the real irrigation efficiency under Tasmanian conditions, the project will identify how much water and cost can be saved through better management, providing a financial rationale for adopting more effective irrigation practices," Dr Avila said.
"Our goal is to quantify how much of the water applied by centre pivots truly reaches the crop root zone. By understanding where and why losses occur, we can help farmers make every megalitre count."
Researchers are also working closely with the TAS Farm Innovation Hub to engage farmer groups and agricultural organisations.
