The effectiveness of irrigation practices in Australian horticulture is currently limited by the availability of useful information to growers. Water applications are often based on observations i.e. gut feel or in limited instances (approximately 1% of growers in Australia) using data from soil probes. Growers have access to weather information from the Bureau of Meteorology (BOM) to help guide their irrigation decisions; however, the stations are often too far from the site to provide relevant information.

Evapotranspiration (ETo) is an established way to calculate water evaporation from the soil, and the transpiration from the plant, to support irrigation decision making. Whilst the BOM currently provides some ETo information it is only available from ~50% of weather stations, is a historic measure only, and is not overly easy to find and so not easily accessed.

Horticulture Innovation Australia in conjunction with The Yield have completed a two‐year research project. The focus was on improving vegetable grower sustainability and resilience by creating models to support growers with the challenge of when and how much to irrigate. The project intent was to encourage efficiencies in irrigation management through development of these models and associated crop coefficients (Kc curves) for four crop types which consider ETo based on the plant growth stage.

After reviewing the approaches using the decision framework, neither drove significantly improved enough results when compared to static Kc curves currently being used. It became apparent that variation in how water moves through soil is a stronger driver of soil moisture variation than variable Kc curves.