Over the last decade, drone spray technology has progressed so much and so fast that it begs the question: Will drones ever replace ground sprayers?

The answer isn’t black and white.

While there’s a consensus among aerial drone advocates that, yes, they will change the way farmers manage crops, the verdict is still out about what that change will look like.

Devin Nohl, owner of Minnesota-based spray drone supplier Tenacity Ag, doubts they’ll ever fully replace ground sprayers for one specific reason.

“Drones are considered ‘aerial application.’ There’s a multitude of chemicals that don’t have a label for ‘aerial application,’ and probably never will,” he says. “If the chemical says, ‘Apply from the ground only,’ it’s illegal to fly it in a drone. I don’t see that changing.”

Those crop protection chemicals Nohl is referring to need to be mixed with large amounts of water — up to 50 or 100 gallons per acre. Conversely, products applied from the air must be highly concentrated, with the most common application rates between 2 to 3 gallons per acre. The largest drones on the marketplace today only have around a 13.5-gallon capacity (compared to around 2,000 gallons for the largest ground sprayers), limiting their practicality, at least for the time being.

Chemical concentration

Would things change if chemicals could be concentrated? Arthur Erickson, CEO of Hylio drones, thinks so. Erickson says chemists are actively working to reduce the droplet size of chemical products so they can be applied in concentrated form.

“Generally, you can get away with less volume — using less carrier — if you have finer droplets. What the industry is now developing with drones is methods of making these droplets smaller and smaller,” Erickson says. “Even though you have less water, you get better absorption into the plant.”

Because it’s so fine, however, wind can blow the concentrated spray off target. Drones inherently solve this problem, according to Erickson. The rotors’ downwash mitigates drift by pushing the lightened chemicals down into the crop.

“Intuitively, just watching it, you can see that the canopy is pushed out of the way,” Erickson says. “The drones aren’t compacting the soil, so you’re not losing yield. And you’re able to penetrate deeper into the canopy.”

Pricing out option

Drones are “so cheap relative to farm equipment — $40,000 to $50,000 for a drone [or less]. Very quickly, a farmer with a few thousand acres can justify that,” Nohl says.

Depending on different factors, he estimates it would take a farmer between one and three years to break even on cost. Practically, drones’ speed and efficiency for some chemical applications are already comparable to ground sprayers. Using a large drone, Nohl says a producer managing 2,000 acres of corn “can expect to cover 300 to 500 acres per day,” reasonably completing the work in a week or two.

Citing a comparative study from Beck’s using Hylio drones, Erickson says researchers “found that, when they did yield calculations at the end of the season, in almost every case the drone outperformed ground operations in terms of ROI.”

Compelling future for drone tech

Drones’ speed and efficiency are only expected to increase as technology advances, according to Andy Kreikemeier, of Nebraska-based drone dealer Infinity Precision Ag.

“The better the batteries become, the better the technology becomes. The better the software and AI that you can get on the drone, the more power we can get. The longer they’ll last, the better they’ll become,” Kreikemeier says. “We’re really talking about a significant increase in coverage that is going to compete with ground application.”

And while production models available today are relatively small, Erickson says larger drones are imminent.

“We’re coming out with a drone that will be in the 30- to 35-gallon size range within two years. I know we’ll have one, and I can only assume that we won’t be alone,” he says, calling the 30- to 50-gallon size range a “sweet spot” for both cost and productivity. “Once they reach that sweet spot, it’ll become a mass-market adoption.”

Ground rigs have a place

Steve Li, an associate professor and Extension weed science specialist at Auburn University, agrees with Nohl’s assessment.

“Will drones ever replace ground rigs? Probably not,” he says. “Not every field is suitable for flying. Not every field is suitable for ground spraying, either. It goes the other way, too.”

Given their massive tank capacity and ability to work beneath obstructions, Li says he believes ground rigs will always have a place on farms. The real question people should be asking, Li says, is can modern farmers “use autonomation and algorithms to replace people?”