sUAS Agricultural Aerial Application Operational Field Test

One of the most promising uses of aerial applications by a sUAS is on small farms where traditional crewed aerial applicators were not practical due to the limited size of the operations. This controlled field test aimed to assess the feasibility and cost-effectiveness of using a sUAS spreading system compared to the traditional manual application of weed killer and fertilizer on cranberry bogs in Western Washington that were less than 10 acres. The aerial application took place over two separate days as scheduled by the farmer for maximum product efficiency. A total of sixty-three flights were necessary to apply the grower-defined dosages of 60 pounds per acre of weed killer and 100 pounds per acre of fertilizer across the 7.35-acre cranberry farm. The average flight time required to dispense a full hopper load was 3.7 minutes. Several new terms for efficiency were developed, including Spreading Efficiency (ESP), Flight Efficiency (EFL), Operational Efficiency (EOP), and Payload Efficiency (EPL). The ESP for both trials was higher than expected and yielded returns above 70%, indicating that over 70% of the flight time was spent dispensing material. EFL can be optimized by minimizing reloading time through a quick-flow filling system rather than the manual funnel method. The EOP varied between 34% and 44%. The EFL played a significant role in improving EOP. There were several other factors to consider when comparing manual and UAS aerial applications, including crop damage, precision, time investment, and cost. In the specific case of cranberry farms, any intrusion into the bogs, whether by foot or mechanical means, should be minimized to limit damage to the crop. Each spreading event took a single worker 3-5 days to apply a product to a 10-acre cranberry farm by traditional methods compared to less than 4 hours with an sUAS, which did not require bog intrusion. Keywords: sUAS, drone, precision agriculture, aerial applications, aerial spraying, crop dusting, Part 137 certification.