Drone spraying is on the rise with broadacre crop spraying becoming more popular as drones get bigger.
Canterbury-based founder of Drone Spray Jono Scott said arable applications are becoming more common as drones grow in size and get more efficient.
“Drone spraying is on the rise across all sectors and agriculture is no exception,” Scott told farmers at a Drone Spray demonstration event organised for arable farmers by the Foundation for Arable Research (FAR) grower group focused on future proofing farm systems.
Built specifically for spraying and seeding, the latest Drone Spray, complete with a 50-litre tank, can cover up to 14 hectares an hour, compared to two years back when Scott said his first drone had just a 16-litre tank.
Lower water rates are a key factor in the efficiency of spraying by drone.
“For some applications we can spray as low as 25% of the water rate of a helicopter operator.
“This is because of the even droplet size of the atomising spray nozzles and precise, even application.”
Drones and their capacity are expected to get bigger as batteries improve, and they will also incorporate more smart technology for applications such as spot spraying of weeds.
While arable farmers will continue to use ground spraying rigs, drones provide an alternative for aerial spraying.
Spraying by drone has strong advantages in paddocks with hedges, trees and high wires or when crop or land damage is best avoided. Drones can also be used at night.
“It is a similar pricing to a helicopter, but more accurate, particularly around the edges.”
While wind can be an issue, as it can with other spraying applications, drone operators have ways to limit drift on the boundaries, such as going slower, flying lower and increasing droplet size.
Before a job is started, an automated flight path is prepared for the drone. This sets a pre-planned route, boundary limits and no-go areas around any obstacles.
Parameters such as height, width, speed and nozzle spray settings can be adjusted during flight.
Drones used by Christchurch-based Scott and his Methven-based colleague Scott Rix can spray a width of 5-8m, depending on the height that the drone is operating.
The drones operate at a height of around 3m for general crop spraying and around 5m on hilly terrain for woody weeds such as gorse and wilding pines, and roof spraying.
The strong downwash from the propeller blades ensures all the spray reaches the target area.
A spreading and seeding attachment is available for slug baiting, spreading and hill seeding.
FAR technology manager Chris Smith said the drones offer another tool in the application toolbox and are particularly useful in areas that are challenging for a ground sprayer – but there are issues to consider.
“While drones have their place and are becoming a commonly used method of application, they may require changes to application rates, which in turn may impact on agchem efficacy and the risk of resistance in pathogen, pest and weed populations.
“Currently, chemical labels are unable to keep up with technology.”
FAR is planning to explore the use of drones for spraying to reduce vehicle use at its Future Farms Systems demonstration site at Chertsey.
A drone will be used on the half of the site that is adopting a more experimental, future-focused approach, while a ground-based boom sprayer will continue to be used on the best practice conventional arable side.
Water-sensitive paper will be used to analyse differences in spray coverage. Agchem efficacy will also be monitored where possible, Smith said.
