Drones are now being used for spray applications in countries around the world. And while not commercially commonplace in Canada yet, companies and ag-service providers continue investing time and resources in the technology.
Despite ongoing technical issues and unanswered practical questions, some think sprayer drones can bring a variety of agronomic, health, and human resource advantages – given the right circumstance.
Why it matters: UAVs might offer a practical alternative for some spraying jobs, if regulations and technical barriers can be worked out.
“From a best management practice standpoint, we shouldn’t be spraying parts of the field if we don’t need to,” says Chuck Baresich, general manager of Haggerty Creek Ltd, a crop inputs and marketing company based in Bothwell.
As custom service providers, Baresich and his colleagues have been looking into drone sprayers for several years. They see the technology as a (potentially) cost-effective and agronomically sensible tool, and have first-hand experience test-driving different designs.
Agronomically, Baresich says the ability to strategically spray specific areas – as opposed to covering the entire field – makes sense from an environmental and precision management perspective. An insecticide, for example, may only be needed in one place, thus sparing beneficial insects in another. Drones, he says, can be a useful tool in such cases.
Strategic spraying can be accomplished with ground application equipment, but that equipment still must be driven into the field. In some circumstances this can damage crops and increase compaction risk. In his experience, too, farmers and custom operator customers prefer to keep product flowing since the machine is driving through anyway.
“It’s also not much fun from an applicator perspective. [We’re] out there for the same amount of time but spraying way less. We could theoretically send the drone out and do zero crop damage and spray only where we need to,” he says.
Lower costs and HR pressures
Baresich also thinks drones offer a cheaper solution compared to other spray technologies. If the number of hours squeezed from a drone equal those of a large self-propelled sprayer, the economics for the smaller, cheaper solution become obvious (with costs for drones from $7,000 to $50,000 in his experience).
He adds the same principle could apply from a human resources perspective. As the size and weight of machinery continues to swell, Baresich says finding qualified operators can be a challenge. Drones can often be transported via pickup, while pre-programed flight operations and built-in safeguards can reduce the risk of human-derived error.
“There are lots of people who can get a pilot’s license to fly a drone,” says Baresich. “The same person driving the drone could do different things as well. It’s not eliminating a person, just changing what they’re doing.
“The whole opening of the labour pool thing I think is underrated.”
Technical and safety barriers
Interesting as drone sprayers might be, Baresich reiterates there are some notable practical challenges. Drones generally can’t hold a lot of liquid, for example, meaning more frequent refill stops. Having to premix the entire solution for quick refilling might also be a challenge in some circumstances.
Differences in mapping can be an issue too. Baresich says this is because many drone technologies rely on more generic images (often derived from Google maps) compared to those used by agronomists and service operators. In such cases the boundaries and areas within the field may not line up. This means the field must be measured again, adding another step to the overall process.
Additionally, he says drone props generate downdraft, which is good for applying some chemicals – but not others. There are also instances where downdraft can harm more fragile crops such as grapes. Baresich says these issues are ongoing and still being investigated, but efforts are being made to eliminate this problem through improved designs.
Jason Deveau, application technology specialist with the Ontario Ministry of Agriculture, Food, and Rural Affairs, also says current drone technology suffers from greatly reduced carrier volumes. Other issues include relatively limited range when it comes to power, as well as significant drift concerns.
“We’re still working to find a fit for it in agriculture,” said Deveau in a recent email. “Beyond some grape work that went on at UC Davis there are big questions surrounding drones in horticulture. Broad acre applications are highly unlikely. Possibly spot sprays.”
In a recent Sprayers 101 article, Tom Wolfe, spray technology expert based in Saskatoon, reiterates that drift is a major concern.
Because a drone payload is relatively small (often between 15 to 24 kg depending on the unit), application volumes have to be lower. This, he says, means spray droplet size must be reduced to achieve the required coverage.
“It’s a simple concept: the less water is used, the smaller the droplets need to be to provide the necessary droplet density on the target,” says Wolfe in the article. “Drift control with coarser sprays requires higher volumes, and true droplet-size-based low-drift spraying can’t really happen at volumes less than, say five to seven US gpa.
“These fine droplets are also more prone to the aerodynamic eccentricities of aircraft.”
Regardless, Baresich says he’s seen spray drop coverage tests that worked well.
“I’ve seen with first-hand experience the technology can work,” he says, adding he does not think drones will completely replace ground application.
Hashing through regulations
Like Deveau, Wolfe says spot-spraying might be the best current use for drone sprayers, with anything larger posing significant practical challenges.
Deveau adds any widespread commercial activity is still, for the most part, hypothetical. This is because regulations around UAV-applications are still being hashed out by the Pest Management Regulatory Agency (PMRA).
“The PMRA is open to the possibility but it requires ag-chem to provide the data. This research is happening,” says Deveau.
While the PMRA deliberates, some companies are trying to get ahead of regulations with designs that specifically address major concerns. Meng Wei, chief executive officer for Ontario drone company Forward Robotics Inc., says their plane-like drone design – called the U7AG – incorporates larger droplets (medium and coarse) and a fixed-wing schematic to reduce drift issues.
“Fixed wing aircraft have different air fluid patterns,” he says. “[It’s]more like a traditional aircraft, thus fitting with traditional aircraft spray regulations.
“We designed our system from the beginning to fit within the PMRA model [for aerial application].”
But larger droplets mean liquid is used more quickly, and there are tank capacity limits to consider. For this reason, and rather then trying to incorporate a larger tank, Wei says they are focusing on shortening refill times and refining maneuverability. Currently, he says the U7AG can refill in about one minute. The overall goal is to commercialize a craft suitable for use on larger acreage Canadian farms.