Spray drift towers road tested by Bongeen cotton grower John Cameron

Darling Downs farmer John Cameron had a CRDC prototype tower installed on his Bongeen property which could identify the presence of hazardous temperature inversions, helping him reduce spray drift risk.

A common event on the Downs, hazardous surface temperature inversions occur when air temperature increases with height from the ground surface, leaving a layer of cool air trapped below warm air.

In this situation droplets can remain suspended in the inversion layer in concentrated form and be carried significant distances from the target area.

Mr Cameron, who is a technical panel chair on Cotton Australia's Transgenic Insecticide Management Strategy committee, said the instrument brought a major issue to his attention.

"The scary bit is the towers were showing the actual inversion was there for more hours than what we traditionally thought it was," Mr Cameron said.

"Most days from evening through to sun up the next morning there's a fairly high risk on the Downs of an inversion. There's been a lot of spraying done in those hours for a whole host of reasons. Now we've got a bit of definitive data, I wonder whether that's why we have been having drift issues?"

Most operators in his area are "on the ball", but that doesn't matter in the event of an inversion.

"The unfortunate thing with an inversion is that quite often it's not your neighbour who's going to damage you in an inversion, it could come from 20 kilometres away," he said.

Now, a $5.5 million GRDC, CRDC and Goanna Ag project will see the rollout of 100 'profiling automatic weather stations' across the grain and cotton regions of NSW, southern and central Queensland in time for the 2022-23 summer cropping season.

An AgEcon study found the warning system could help the cotton industry avoid $40 million in losses and costs associated with spray drift over five years.

GRDC chair John Woods said until recently, there had been no reliable and accurate method to determine when inversion conditions were hazardous for agricultural spraying using real time data.

"These hazardous inversion conditions exist most nights of the year for undefined periods, so we need to have the ability to know exactly when they are occurring and stop spraying," Mr Woods said.

CRDC executive director Dr Ian Taylor said the partnership with Goanna Ag built on six years of collaborative research and development from the RDCs.

While the towers were valuable, Mr Cameron at Bongeen said it also came down to best practice at the operator level.

"At the end of the day, our duty of care as farmers is that every chemical we use should stay on the area that it was intended to be applied to. That's what the community expects of us and that's what best practice is," Mr Cameron said.

"There's enough information and science and knowledge out there to define what you should be doing and how to do it and the weakest link in the chain is probably the decision maker."

Read more