Drone Spraying Considerations
Weather tracking by climatologists shows fewer days in the year suitable for field work than a decade ago. Due to poor ground conditions, these limited windows of opportunity reduce the likelihood of timely pesticide application in field crops with traditional spray equipment. Until recently, the only alternative was using a crop duster with an airplane or helicopter. The development of Unmanned Aerial Vehicles (UAVs), more commonly known as drones, has the potential to be an alternative application technology.
Alan Leininger, OSU Extension Educator in Henry County, Ohio, says that there are several potential applications that UAVs provide to production agriculture. Still, there are also some hoops to jump through. Using drones to spray should be considered another “tool in the toolbox” for farmers. Drones may not be practical to apply a burndown application across an entire field; however, areas that may be a good fit for using drones to spot spray include weedy areas, areas that frequently lay wet or are hard to get along tree lines.
“There are many challenges that exist with this emerging technology,” said Leininger. “Should a drone sprayer be treated like a crop duster or like a low flying boom? The answer to that question impacts how the rules and regulations are interpreted by the Federal Aviation Administration (FAA). Currently, they are viewed as a crop duster which requires special licenses (Part 107 and Part 137 license) in addition to the private or commercial pesticide applicator license.”
Another regulatory challenge is that no drones can be flown commercially that weigh over 55 pounds without an exemption. “Those exemptions are difficult to get,” said Leininger. “Without an exemption, then the payload capacity is limited to the difference between the weight of the drone with spray equipment and the 55-pound limit. Once that amount is calculated, then based on the pesticide product label and the required minimum application rate, that will dictate how much product and how many acres can be covered.”
Traditional chemical application factors also apply. The rate of travel, ground speed, and boom height impact the effectiveness of the spray application. “Everything that we know from ground sprayers needs to be considered when applying pesticides with a drone,” said Leininger. “We have a lot of good documentation from ground sprayers, but the same may not apply when using a drone. What tips should be used, and what boom pressure is needed to get the correct droplet size? We don’t know if we can apply the same knowledge from ground sprayers to drone sprayers.”
Other regulations include the need for a “line of sight” by drone operators to have a constant view of the drone when flying. “This can be a challenge based on the field size and layout with tree lines, terrain, and woodlots,” said Leininger. “I think in many ways, this technology is so new that the FAA doesn’t know what to do with it yet. I think that a lot of things that we are studying and several groups are working to gather data that the FAA can use to re-evaluate the technology and the numerous applications it has. Many of those applications are not agricultural.”
Another factor being evaluated is the ability of one operator to fly multiple drones simultaneously, making it much more efficient for a farmer or operator to cover more acres by operating multiple drones in unison. The other factor in efficiency is reloading and recharging the drones to keep them flying and applying product, requiring a truck or trailer to serve as a tender and allowing for mixing the products before loading the drone and changing the battery. With multiple drones flying and making applications simultaneously, it will be essential to have a support system to reload, recharge, and keep them flying efficiently.
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