Unmanned aircraft, also known as drones, have several uses in farming operations. One use that continues to increase is the application of pesticides and plant growth regulators. Drones can apply crop products precisely in areas where aircraft travel is difficult. There are regulations governing the use of drones in agriculture.
An agricultural spray drone applies ripener to sugarcane.
Aircraft weighing less than 55 pounds when loaded
Aircraft weighing 55 pounds or greater when loaded
In both cases, business insurance is necessary for drift claims and property loss.
Operators must be aware of several factors that influence the effectiveness and limitations of a spray drone. Like spraying with a tractor, spray nozzles can impact pesticide drift and effectiveness for targeting a potential pest. It is important to conduct pattern testing prior to pesticide application to evaluate the effective spray width of the spray drone, which varies from model to model, application height, application rate per acre, nozzle type and weather conditions. Some drones have rotary or centrifugal nozzles that spin a serrated disk below a liquid outlet and create an adjustable droplet size depending upon rotation speed of the disk and the disk design (double cutter, etc.). These nozzles have more concise, smaller droplet sizes (<300 um) than standard nozzles but may require higher flying altitudes (10 to 15 feet above the crop surface) to create uniform coverage. It is recommended to fly crosswind, if possible, to preserve application patterns.
Long-distance drift (>300 feet) seems to be negligible with drones, but they can have quite significant side drift (20 to 50 feet) dependent upon wind conditions and nozzle type. Lowering the travel speed around borders can help reduce this effect.
A limitation of spray drones is battery life. Batteries typically last for 10 to 12 minutes per flight before needing to be recharged. Extra batteries and a generator that is appropriately sized to recharge the batteries is important. To gain maximum efficiency with spray drones, spray the longest distances possible at the fastest speeds, which still allows timely returns (i.e., large fields may need to be broken into smaller sections, etc.). Research has shown faster speeds create wider swath widths. Some refills may require driving to the drone on the turn row or headland, as opposed to flying the drone to a distant refilling location. Chargers need 220 to 240 volts at 30 to 50 amps to provide fast 10-minute charging. For sugarcane and other tall crops, an elevated platform may be necessary to visually observe the drone during use. The elevated platform can also be used for landing and take-off, which saves energy to climb up and over the crop. Every turn or unnecessary flight movement decreases the amount of time the aircraft can fly.
If you have any questions or need help pattern testing a spray drone, Randy R. Price can be reached at the LSU AgCenter Dean Lee Extension and Research Center, 8105 Tom Bowman Drive, Alexandria, Louisiana. Price can also be emailed at rprice@agcenter.lsu.edu.
An agricultural spray drone applies ripener to sugarcane.
A drone sits on a headland prior to flying a mission.
An agricultural spray drone sits on the bedcover of a truck.
Drone with florescent dye sprayed on the soil.