Effects of Spray Parameters of Drone on the Droplet Deposition in Sugarcane Canopy

Sugarcane is an important sugar crop in China and the world. Manual sprayer is the main method for pesticide application in sugarcane in China, the spray efficiency of which is low and chemical waste is enormous. Aerial spray by drone has the advantages of high efficiency and flexibility. However, effects of spray parameters of drone on the droplet distribution on sugarcane canopy have not been reported. In the present study, spray experiments were conducted with orthogonal design with three factors (spray volume, flight height, and flight velocity) and three levels by quad-rotor drone. For droplet deposition density, it was found optimal when 15 L/ha of spray volume, 3 m of flight height, and 4 m/s of flight velocity were used for the upper layer. For the mid-layer and lower layers, it was found suitable using 15 L/ha of spray volume, 2 m of flight height, and 4 m/s of flight velocity. For droplet deposition uniformity, it was found optimal for the upper layer when using 15 L/ha of spray volume, 4 m of flight height, and 4 m/s of flight velocity, and that 15 L/ha of spray volume, 3 m of flight height, and 4 m/s of flight velocity for the mid-layer, and 12 L/ha of spray volume, 3 m of flight height, and 5 m/s of flight velocity for the lower layer. For droplet deposition penetration, it was appropriate using 12 L/ha of spray volume, 4 m of flight height, and 4 m/s of flight velocity. Under comprehensive consideration of the density, uniformity, and penetration of droplet deposition, the optimal spraying parameters were 15 L/ha of spray volume, 3 m of flight height, and 4 m/s of flight velocity, which could be used as a reference parameter of drone when applied in sugarcane crop.