RESEARCHERS have taken to the skies in an effort to reduce the impact of barley grass on the upper Eyre Peninsula.
Minnipa Agricultural Centre-based SARDI senior research officer Amanda Cook said while barley grass continued to be a major weed in the region, unmanned aerial vehicle imagery could offer an alternative tool to identify, monitor and manage the weed in paddocks.
A three-year SAGIT-funded project monitoring barley grass in broadacre paddocks has shown UAV imagery potentially offers growers a quick, reliable and affordable option to verify grass weed density in paddocks.
“The drone will be flown over each season to establish where barley grass is an issue in the paddock and if we have resistant weeds, and track if they are spreading or if they are remaining in the same area,” Mrs Cook said.
“UAV technology may be useful for farmers as a cost-effective tool to enable regular collection and analysis of paddock data.”
Barley grass weed density was monitored in three paddocks – two paddocks at Minnipa and one at Yaninee, in barley and pasture crops.
A UAV was flown three times during the 2017 growing season. The first flight at a height of 118 metres was on August 14, followed by September 28 and October 3, with two types of UAVs used – a DJI Matrice 100 and a Mavic Pro.
At the same time as each UAV flight, grass weeds were measured in-crop at more than 30 GPS sample points.
Mrs Cook said weed seed germination trays were used to verify barley grass germination patterns and determine if it was an early germinating population or later germinating, after the crop was established – making it more difficult to manage.
To analyse weed locations at a paddock level using the UAV imagery, geospacial analysis tools were used to automate the section of likely weed impacted areas.
“UAV technology has the potential to help farmers with making weed management decisions,” Mrs Cook said. “Many farmers are using UAVs and we are looking at ways to apply that technology usefully in farming systems.”
Grass behaviour pattern revealed
A THREE-YEAR trial to monitor barley grass in broadacre paddocks on the Eyre Peninsula using unmanned aerial vehicle imagery produced interesting results in its first year, SARDI researcher Amanda Cook says.
“The poor season meant the first flight time on August 14 took images of crops at only the four leaf stage, and lower than expected grass weed germination,” she said.
One paddock was confirmed to have resistance to Group A herbicides as the imagery determined barley grass weed patches were circular and spreading.
In the barley crop at Minnipa, it was difficult to detect areas high in barley grass numbers because the photos showed a large percentage of weeds were within crop rows. But, results showed pasture areas provided clearer weed signatures for data analysis.
“A Minnipa paddock was intensively grazed which changed the appearance of grass weeds in the imagery, but at Yaninee there were obvious barley grass patches,” Mrs Cook said.
Wisdom Data and Mapping’s Scott Gillett, Loxton, analysed the UAV imagery.
He said the weed patches were identified with a colour spectrum, then software identified the weed throughout the images.
“It determines where the weeds are located in the paddock and it also creates a likelihood map of how accurate the prediction is,” he said. “UAV imagery has made paddock analysis more accessible to all farmers.”