Reduction of UAV pesticide drift through adaptive wind speed and flight altitude strategies

Abstract

Pesticide application is vital in modern agriculture, with global use reaching 3.70 million tonnes in 2022. UAVs have emerged as a more efficient, precise, and cost-effective method for pesticide spraying, surpassing traditional methods. However, concerns about pesticide drift and worker health risks remain significant despite advancements. This study evaluated adaptive UAV pesticide spray protocols aimed at minimizing drift in rice fields. Utilizing the DJI Agras T10 drone sprayer equipped with XR11001 flat spray nozzles, experiments were conducted under varying wind speeds and flight altitudes. Spray performance was assessed using water-sensitive paper, measuring percent coverage, droplet density, and deposition within (on-target) and beyond (off-target) the spray swath. Results indicated that flight altitude significantly influenced on-target deposition, with its quadratic effects impacting on-target droplet density and on-target spray uniformity. When combined with flight altitude, wind speed affected off-target droplet density and significantly altered off-target drift behavior. Most off-target pesticide drift occurred within 4 meters outside the swath width and decreased significantly beyond this distance. Using Response Surface Methodology, optimal conditions were identified, achieving over 99.72% desirability at 1.2 meters flight altitude and wind speed ranging from 2.0 to 2.99 m/s. The confirmation test resulted in an actual off-target percent coverage of 0.03%, off-target droplet density of 0.4 droplets/cm², and off-target deposition of 0.0016 µL/cm², all of which are within the acceptable range. Therefore, the model is validated and deemed reliable for predicting off-target drift.