The unmanned aerial system (UAS), is an eight-rotor “octo-copter,” and uses high-tech cameras to assess the status of canopy vigor and relate that to irrigation water use and evaporation from grapevines. The flights are part of a long-term Washington State University (WSU) study on subsurface irrigation in vineyards.
“We can do measurements on the ground, but they’re time-consuming, laborious, and take a while to process,” Lav Khot, assistant professor in the WSU Department of Biological Systems Engineering and affiliate faculty for the Center for Precision & Automated Agricultural System (CPAAS), said. “With the small UAS, we can get real-time measurements in minutes with incredible accuracy. It’s a huge advantage.”
The study Khot is involved in is an effort to reduce the amount of irrigation water used to grow winegrapes by applying water directly to the roots of a vine in the ground, instead of dripping water on the ground near the trunk. The project is led by WSU professors Pete Jacoby and Sindhuja Sankaran, both affiliate faculty members of CPAAS.
In the first year of the study, Khot said one treatment used 60% of the normal amount of water, and the vines had no yield differences. But the three-year project is testing a variety of fields to see what levels of subsurface irrigation, at what intervals, provide the best outcome for growers.
“It’s very early, but it seems subsurface irrigation is working,” he said. “The berry size is the same as (with) control treatments, but we need more data. We’re really excited about the potential.”
The octo-copter can carry up to nine pounds of equipment to measure the temperature of the vine canopy and how water transferred from the roots to the canopy is being used during various growth stages.
The UAS works by flying a few hundred feet above the vines, hovering in preprogrammed locations for a defined time period, then moving to the next location. Khot stitches together the images to get data for an entire vineyard study plot.
The unit has built-in fail-safe features and geofencing capabilities; if it loses contact with its ground pilot, it will return to where it took off. Per FAA guidelines, it can only fly in “line of sight.”
“We don’t want it to crash and we don’t want it to fly off and potentially damage itself, its payload or others’ property,” Khot said.