During July, twelve frost fans were installed on the almond orchards at the Mooral property in NSW. Together with the “anti-frost” sprinkler system, the fans help to protect the high value almond crop for investors and lessees.
Frost protection is an important component of effective orchard management, particularly during spring when the orchard’s fruitlets have just emerged from the flower casing after pollination. During this time, periods of subzero temperature can freeze the small fruitlets – damaging the embryo inside.
Spring frosts can occur when an inversion layer traps cold air at ground level. The frost fans are designed to combat this by drawing warmer air from above into the orchard. Initial testing has demonstrated that the fans can lift ground temperatures by two to three degrees, with up to four degrees expected during full operation.
Each frost fan, like the one pictured here, is 12 metres high and has a slightly downward pointed six metre wide fan blade. Powered by a 180 horsepower diesel engine, the fan head slowly rotates to cover 360 degrees and has an effective radius of around 130 meters.
The orchards owned by the Rural Funds Group are located on two properties – Yilgah and Mooral both near Hillston, NSW. RFM weather data analysis of Mooral has shown that the prevailing wind drift has most effect on this property’s western side. There, cold air accumulates on the ground and gets pushed into the orchard. The frost fans were installed on this side of the property to maximise their effectiveness.
Previously, RFM also installed sprinklers on Mooral to assist protect against frost. By drawing ten to twelve degree water, and spreading it across the orchard, localised temperatures could be raised by approximately one degree.
The effectiveness of the sprinkler system is dependent on water delivery capacity and output. Given the western side of the property is now protected by the fan system, sprinkler water resources can be focused on the east. The result is a more complete and effective anti-frost system for the almond orchards.