Crop Scouting Drones
Dale Cowan attracts a crowd when he sets up beside a cornfield in southwest Ontario. It happens several times a day in peak season, as he takes out his bright yellow eBee for another field scouting trip.
Cowan’s eBee is one of the newest among hundreds of unmanned aerial vehicles (UAVs) for agriculture on the market today in North America.
“I usually draw a crowd when I’m out in a field with a drone,” he says. “Part of the license agreement is that I have to keep people 100 feet away from the foot of the operation, but I’m not there very long. It’s in and out.”
He can easily survey 1,000 acres a day over small Ontario cornfields. Flying at 45 km/hour (just under 30 mph), the drone can cover 100 acres in 20 minutes. Battery life is such that it could cover a full section of land on the wide-open prairies with one flight.
As an agronomist, Cowan began looking at remote-sensing images from satellites and aircraft in 1994. They’re expensive and not very timely, he says, compared with the UAV option.
For $5 an acre, he now provides timely high-resolution (4-inch) NDVI (normalized difference vegetation index) images. A typical flight captures 300 to 350 images in 10 to 20 minutes.
Images are postprocessed in his shop and are available within 48 hours for detailed evaluation. In the old days (before 2013), his image request for a typical 100-acre field would cost $1,500 to $2,000. Sometimes, the image had a cloud over the field. It was almost never available at the right growth stage. It covered three to six sections and had to be processed in his shop for the specific field site.
“Drones all have real-time communication. You pilot these things yourself at a 400-foot elevation. When the nose of a plane gets blown off course, it stops taking pictures and it tells you. When it’s too windy, they return home. Any wind over 20 km/hour (about 12.5 mph) and gusting means you probably can’t fly. Limits are mostly wind and the sky conditions,” he says.
Cowan is senior agronomist for Agris Co-operative Ltd. in Chatham, Ontario. The company purchased a Swiss-made UAV, the Swinglet, in 2013 to test the market, the operation, and the performance. It paid about $25,000 for the 2.2-pound aircraft. In 2014, it traded the Swinglet for a $30,000 eBee.
The eBee has a 33-inch wingspan, a digital camera, and a pile of avionics. Flights are preplanned by the operator using Google Earth, then they are loaded into the eBee’s on-board memory.
In flight, the plane will fly itself but can be redirected by the operator. It needs about 30 yards for takeoff and, with practice and good conditions, will land on the grass beside the operator’s feet.
Flying is the fun part. Finding it when a battery runs out of juice isn’t so bad. Cowan once walked through 8-foot corn to find a drone, following the GPS signal trail.
“You always know where it is,” he says.
Behind the scenes
Preparation for each flight requires legal paperwork. Transport Canada controls authorization of drones, issuing Special Flight Operation certificates. Cowan needed a two-day abbreviated ground school with a qualified flight instructor before his first drone flight.
“I’m always very cautious and very aware of my airspace. I know where every airstrip is in Ontario,” he relates. “I’m sharing the air with licensed pilots. They’re operating with a minimum 500-foot ceiling so I should never run into a licensed plane, except around an airport.”
To fly a drone in a specified area within a control zone, he files a notice with NavCanada stating the drone will be in that area at this altitude between these hours of the day.
After the flight, processing images into a single field shot that is useful takes an hour or two with professional skills.
“You need lots of computer space and a fairly good skill set to do the photo mosaic afterward,” Cowan says.
Put tech to work
Cowan has two cameras for the eBee. He flies each field twice: once with the standard color digital camera and a second time with a camera filming in red and infrared.
“Infrared is where I’m really picking up a lot of the subtle changes in crop development,” he explains. “I see things happening in the field that the color image doesn’t show me. I can see nitrogen deficiency happening maybe a week before I’d pick it up with my naked eye.”
For 2015, he plans to have a camera that picks up infrared plus three bands of light – red, green, and blue (multispectral) – to produce high-quality NDVI images. Because the images overlap, it also will be useful for 3-D elevation maps at a 10-cm vertical accuracy.
His next step is to improve nitrogen management in corn by looking at chlorophyll content with the images.
“I’ll take some flights just prior to tasseling and look in detail for N deficiency. I’ll do some tissue testing to verify the imagery and try to calibrate so I know where to go for extra nitrogen, if I need to,” Cowan says.
Agris Co-operative also found manganese issues in soybean crops by using the drone. “I know exactly where to put manganese and not waste money somewhere else,” he notes. “If I do the flight on a timely basis and have the equipment all organized, I can do a lot more effective job.”
Long term, he says, fields are variable, and management changes are always being considered.
“If I’m looking at different nitrogen rates, I can really nail down the management. If I gain insight, beyond the obvious, as to what’s causing variability, then I can decide whether it’s something I can manage. That’s the value point for ag drones.”
The eBee isn’t the best or the cheapest of the ag drones. Cowan says he can buy a smartphone-controlled helicopter for about $300 and put a camera on it. He also discovered a local company making $90,000 unmanned copters – mainly for the U.S. military.
Copters work well for spot surveillance in the middle of a crop. A fixed-wing drone is better for coverage.
“Raw images now can be processed by private companies and returned the next day,” Cowan says. “John Deere, Monsanto, and others are racing into cloud computing services. They have the layers for GIS, and they sure want your data.”
A 2013 report by the Association for Unmanned Vehicle Systems International identifies 210 companies and 808 platforms in North America. About 70% were fixed-wing products; 20% were rotary. Some are lighter than air, have flapping wings, and come in other configurations. Flight times often are less than an hour.
“UAVs have exploded on the market in the last 24 months,” he notes. “If you’re interested in one for your own farm, talk to a crop consultant first. A few crop consultants in Ontario have them. In the U.S., talk to someone familiar with the FAA. Right now, if you gain value from flying a device, you’re commercial and no longer a hobbyist.”