Researchers at University of California, Davis, in cooperation with the Yamaha Motor Corporation, are testing UAV crop dusting on the Oakville Experimental Vineyard at the UC Oakville Station using a Yamaha RMax remote-controlled helicopter. The purpose is to study the adaptation of Japanese UAV crop dusting techniques for US agriculture, but not all the hurdles they face are technological.

The use of aircraft for crop dusting and seeding is over a century old, but it’s not a panacea. Flying aircraft low over farmland is best suited for areas like the Great Plains of North America, which are flat and relatively free of obstacles like trees or power lines. In built-up areas, rugged terrain, or mixed-use regions, it isn't feasible to distribute chemicals from a plane or helicopter and even under ideal conditions, flying close to the ground can be hazardous. There’s also the risk of the pilot and people on the ground being exposed to dangerous chemicals.

If you wanted to find a place not suited to crop dusting, it would be hard to beat Japan. It’s a mountainous, heavily populated country with lots of trees and buildings where farms with small fields are interspersed closely with settlements and all manner of other things like a semi-rural crazy quilt. But it’s also a country with an aging population providing fewer young people to work the land, so there’s a strong imperative to automate as much as possible.

The idea of using drones as crop dusters and seeders may be a novelty in the West, but in Japan it’s old news. Unmanned helicopters have been on the job for over 20 years since Japan’s Ministry of Agriculture started promoting the idea in the 1980s. In 1991, small remote-controlled helicopters were used to spray rice fields and today UAVs spray 40 percent of the nation’s rice crops. In addition, unmanned helicopters are used to spray, wheat, oats, soybeans, lotus roots, daikon radishes, chestnut groves and continues to expand to other kinds of orchards and vegetable fields.

One of the major players in this, and the center of the UC Davis study, is the Yamaha RMax. Controlled by a ground operator, the motorcycle-sized helicopter is powered by a two-stroke, two-cylinder 2.4-liter engine and is capable of lifting a payload of 28 kg (61 lb). It’s fitted with a spray applicator system and can spray at about 15 mph (24 km/h). There are 2,400 RMax helicopters currently flying in Japan and through they’re used mainly for spraying and seeding, they’re also employed in remote sensing, precision agriculture and frost mitigation.

California agriculture has similar problems to Japan with a some areas marked by a quilt of small holdings in a complex geography, so since November 2012 UC Davis has been running a program to adapt Japanese UAV methods to American needs.

Test papers being fitted to grape vines

“We have more than two decades of data on the performance of the RMAX in Japan, but we don’t yet have that kind of information on its use in the United States,” says Steve Markofski, a Yamaha business planner and trained RMAX operator.

Bringing the Japanese model to the United States has a number of obvious benefits. It brings a degree of precision to agriculture over using tractors while removing the hazards of a low-flying pilot. Pesticides can be applied with greater accuracy, which reduces not only costs, but also exposure of farm workers as well as reducing the environmental impact.

Currently, UC Davis is studying the distribution of spray over a vineyard by using the RMax to spray colored water over grape vines kitted out with water-sensitive test paper. The paper shows up water droplets as blue specks, which can be recorded and analyzed by computer.

Preliminary results show that the helicopter is stable even in gusty conditions and that the turbulence thrown up by the rotors distributes the spray even under the leaves. The hope is that the study will eventually show how safe and efficient helicopter spraying is and how well it compares to tractor spraying. Another benefit may be close-quarters crop monitoring with some Napa farmers expressing an interest in using unmanned helicopters to take images of vineyards to monitor vine health and determine harvest schedules.

You would think that with decades of Japanese experience we’ll be seeing helicopters buzzing around the Napa Valley very soon, but not all the problems revolve around technology. The US government still doesn't recognize the use of UAVs by civilians and until the law is changed in 2015, they must operate under very severe restrictions. UC Davis as a limited FAA permit, which very few other universities have, that took its two pilots five months to obtain.

The Rmax can only fly over very specific agricultural areas, cannot operate within five miles of an airport. the operators must give the FAA 48 hours warning of a flight, and even then it can only fly at below 20 feet (6 m).

UC Davis stresses that the entire vineyard has been declared an emergency landing area and that the helicopter is designed to hover and land automatically if it loses its control signal. “This site not only offers a working-vineyard situation, it also meets all of our federal requirements for flight zones for remote-controlled aircraft,” says Ken Giles, a UC Davis agricultural engineering professor and lead researcher on the project.

Giles also addresses privacy and safety concerns stating, “As a citizen, I share those reservations and agree that we need to be very careful about how we use unmanned aircraft. But with the color, size and noise of a motorcycle, this helicopter that we’re testing is anything but stealthy and would be a great disappointment to anyone hoping to use it for espionage or other covert purposes. And, our work is being conducted with the anticipation that the aircraft would be flown by the landowner or by someone hired by the landowner. In other words, that person would want the aircraft to be flying over his or her land.”

If all goes well with the current round of tests, UC Davis plans to expand the program to almond groves in the California Central valley.

The video below outlines the UC Davis study.

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