For nearly 30 years, Agriculture Victoria has been supplying Sunraysia irrigators with weekly information on evapotranspiration (Eto).
Now, according to its irrigation extension officer Maxine Schache, things are about to be turned on their head.
Maxine says evapotranspiration is an estimate of the loss of water from both plants and the soil.
She says the main drivers of evapotranspiration are sunlight, wind, humidity and temperature.
“Evapotranspiration information is used by farmers to more accurately schedule irrigations to help achieve top yields and improve water productivity,’ she says.
“For many years, Agriculture Victoria has provided weekly Eto information on a graph for Mildura, Red Cliffs and Robinvale irrigators, who can then overlay the generic graph to reflect the water use of the crop(s) grown on their property.”
However, one of the issues has been the out-of-date data flow – decisions are being made retrospectively, based on figures from the previous seven days.
“With better predictive information now being available we will be including the coming week’s daily Eto values as well, for both Mildura and Robinvale,’ she says.
“This will help irrigators make better decisions on when to order water, particularly as there is more drip irrigation in the vineyards and orchards that need to be irrigated more frequently than weekly.
“The Eto values are calculated from weather station readings of solar radiation, temperature, humidity and wind.”
Maxine also noted as Mildura and Red Cliffs are close both geographically and meteorologically, Agriculture Victoria will no longer supply information for Red Cliffs as part of the information upgrade.
This is because the Eto values for Mildura are almost identical to Red Cliffs, and can be used with a great deal of confidence.
However, she cautions irrigators shouldn’t rely on the evapotranspiration graph alone to schedule their irrigations.
“The best results are obtained when used in combination with soil inspection, soil moisture sensors and growers’ own experience, as well as other indications of crop stress.”
