Research HighlightsDrones: An In-Season Application Option
In this article, you’ll find details on:
- Drones can effectively make in-season applications in soybean and corn rotations, and farmers should consider many factors when deciding if that option makes sense for an operation.
- When calibrated and using optimum spray volume, drones can apply in-season fungicides as well as or better than helicopters.
- Drones can effectively fly small-seeded cover crops into standing corn to ensure strong establishment ahead of soybeans.
By Laura Temple
When it comes to ag technology, the line between practical tools and cool toys can be fuzzy. Unmanned aerial vehicles, commonly known as drones, can fall on either side of that line.
“We started looking at the feasibility of drones for in-season input applications in 2019, when no data was available,” says Andy Kness, senior agent for University of Maryland Extension. “Despite predictions about the value of drones, farmers who had them weren’t necessarily replacing them, and a business model for custom application with drones had yet to be proven.”
Kness received Soy Checkoff support from the Maryland Soybean Board to gather unbiased data on how drones might serve as an application tool for farmers. He looked at two common in-season inputs for soybean and corn rotations: fungicide applications and cover crop seeding.
“It’s impossible to do all the fungicide application that needs to be done at the same time with just ground rigs,” he says. “And timing to ensure cover crop establishment can also be a challenge. We wanted to see if drones could be a viable tool for some farmers.”
Carrier and Calibration Key for Coverage
For fungicide applications, Kness quantified drone spray coverage. Using commercial drones, he sprayed both soybeans and corn with water-sensitive cards at the top, middle and bottom of crop canopies.
“As expected, coverage was better higher in the canopy than lower,” he reports. “In soybeans, in-season fungicides just need to reach the upper third of the canopy, so that isn’t an issue.”
Initial trials found that drones typically sprayed about 12 to 25 droplets per centimeter, which was below the recommended 20 to 40 or 50 droplets per centimeter. In following years, he learned that increasing spray volume from 1.5 gallons to between 2 and 3 gallons per acre allowed drones to deliver the target droplet density.
“Now, product labels specify minimum carrier volumes,” Kness says.
“We also learned that drone operators need to proactively calibrate for swath width to ensure even coverage,” he continues. “With the models we used, a 20-foot swath was the sweet spot.”
In related trials, also funded by the Maryland Soybean Board, Kness compared drones to helicopters for in-season fungicide applications. He observed that drones spray finer droplets, and that helicopter droplets are larger due to machine speed.
“Drones are at least as good as helicopters, with potential to do better,” he reports. “If farmers are satisfied with helicopter applications, they will be satisfied with drone applications – as long as the drones are set up properly.”
Seeding Cover Crops Ahead of Soybeans
Kness used the same drone models with different application equipment for cover crop seeding trials. Flying cover crop seed into standing corn to establish a cover crop ahead of soybeans was already a common practice, and that’s what he did with the drones. Past experience showed that cover crop seed doesn’t penetrate the soybean canopy well when it is flown on.
His trials used radish seed as the cover crop, as it is smaller and has a lower seeding rate, so drones can efficiently fly it on. He believes clovers and annual ryegrass could also be considered for drone seeding. Because of the size and seeding rate associated with grasses like cereal rye and wheat, flying them on isn’t economical.
“Drones can work for cover crop seeding,” Kness says. “The data collected from these trials helped validate that, and Maryland cover crop programs now accept drone seeding.”
He noted that one field in the trials contained two different corn hybrids, and the cover crop established better in the shorter hybrid. That’s something for farmers to consider for areas where drone seeding makes sense.
“The propeller wash from drones also helps push seed further into the crop canopy for better seed to soil contact,” he adds.
Finding the Fit for Drone Applications
Kness says that as drone technology advances, their efficiency for these uses is improving. Larger drones can carry more fungicide or seed, reducing refill time.
Farmers should consider a variety of factors when deciding if drone application is a tool that fits their operation.
- Scheduling timely custom ground or aerial application can be challenging.
- Drones may initially be cheaper than ground rigs, but consider durability, expected lifespan for each option and the acres that need to be covered.
- Both drones and ground rigs need an accompanying support system for filling. Both require a truck or trailer with tanks, but drones also require batteries and a generator. That should be accounted for in cost.
- In hilly fields, it’s challenging to operate ground rigs without running over quite a bit of the crop. Drones offer a significant advantage in these fields.
- Drones can apply products more precisely than airplanes or helicopters around field edges. They can also get closer to trees and power lines.
- Drones carry licensing and calibration requirements.
To share the practical information gathered from this research, Kness hosted an agronomic crop drone school during the 2024 season, with plans to do the same in 2025, both with Soy Checkoff support. The day of classroom instruction and in-field demonstrations equips growers and custom drone applicators to effectively use drones for in-season fungicide applications and cover crop seeding.
Additional Resources
Can Fungicide Applications via Drones Effectively Control Soybean Foliar Diseases? – SRIN article
Drone Seeding Cover Crops into Standing Soybeans – GROW article
Drones, Cameras, Droplets, and More -YouTube video
Using Drones to More Effectively Target Weed Escapes – SRIN article
Meet the Researcher: Andy Kness
Published: Aug 4, 2025
The materials on SRIN were funded with checkoff dollars from United Soybean Board and the North Central Soybean Research Program. To find checkoff funded research related to this research highlight or to see other checkoff research projects, please visit the National Soybean Checkoff Research Database.
