SPRAYING agricultural fields with unmanned helicopters may be an option in the near future, or at least that is the hope of University of California-Davis (UC-Davis) researchers.
The U.S. lags behind Japan in using unmanned aircraft systems (UAS) to complete certain agricultural operations like seeding or spraying.
In 1983, the Japanese government asked Yamaha to develop a utility-use unmanned helicopter for crop dusting to help reduce labor and expenses for Japan's rice farming industry. As a result, Yamaha developed the lightweight, remote-controlled RMAX helicopter.
Yamaha RMAX helicopters spray about 2.5 million acres annually in Japan, accounting for 40% of the rice paddies.
The UC-Davis research team is testing the RMAX's aerial application ability over a vineyard in the center of Napa Valley, Cal., to determine the role it could play in U.S. agriculture. The vineyard was selected as the experimental site because it closely resembles Japan's rice fields in size (approximately five acres) and is adjacent to residential areas.
At this point, the UC-Davis team has only applied colored water over the grapevines. In order to study the coverage pattern, a web of water-sensitive test paper was fitted over the grapevines. The helicopter is equipped with two dual tanks, giving it the capacity to carry 16 liters of liquid, and it has a recommended maximum spraying speed of approximately 15 mph.
Preliminarily, UC-Davis reported that the helicopter provides thorough coverage across the vineyard and that the air currents stirred up by the helicopter rotors cause the spray to reach even the undersides of the grapevine leaf canopy. Overall, the researchers have been impressed by the stability of the helicopter, even in gusty winds.
Eventually, the team will shift to aerial application of common pesticides and herbicides used in the agriculture industry. The study will also compare the unmanned helicopters to tractor-driven spray rigs in terms of cost, efficiency and operator safety.
For instance, spraying two acres of the Napa Valley vineyard traditionally takes one hour, but the RMAX can spray 12-15 acres in an hour.
"For the half-hour it takes for the tractor rig to water an acre of crops, the RMAX can do the same space in a fraction of that time," said Ken Giles, a UC-Davis agricultural engineering professor and lead researcher on the project.
Based on research and application use in Japan, the RMAX reduces the hazards for low-flying pilots and increases the accuracy of pesticide application. Further advantages include no soil compaction, limited or no crop damage and the ability to more safely handle challenging terrain, such as slippery hills.
Challenges to UAS
At the moment, the Federal Aviation Administration (FAA) prohibits the commercial use of UAS in U.S. airspace.
However, the FAA Modernization & Reform Act established important provisions for the integration of UAS into the national airspace system by September 2015. If and when FAA approves the low-level, line-of-sight operation for commercial use, agricultural companies can use UAS to monitor and spray crops.
UC-Davis is among five universities that received FAA approval to conduct UAS research. Besides receiving the proper clarification from FAA, Giles had to obtain his commercial pilot license — a requirement for anyone who plans on piloting unmanned aircrafts.
In accordance with FAA requirements, the RMAX can fly only over very specific agricultural areas and cannot operate within five miles of an airport. The operators must give FAA a 48-hour warning of a flight, and the craft may only fly below 20 ft.
In general, the purchase price of UAV will limit its quick adoption by farmers, but it could be considered a cost saver for some commercial businesses serving agriculture.
Specifically, the RMAX's cost can range from $86,000 for a base model suitable for agriculture with a single global positioning system to $1 million for a full-package deal equipped with computers, monitors and four camera systems.
The main hurdle for using UAS to spray U.S. field crops is the size of the average agricultural field. Specialty growers will probably benefit the most from bringing the Japanese model to the U.S. Time will tell if it is as economical and practical to spray an 80-acre field of corn as it is to treat five acres of rice in Japan.