Spray deposition from a remotely piloted aircraft on the corn crop

Abstract

The use of remotely piloted aircraft (RPA) has grown in agricultural spraying around the world, but there is a lack of research data to assist users in making more assertive decisions due to its recent nature. This study aimed to evaluate spray deposition in corn using an RPA DJI AGRAS-MG-1 at two application heights compared to the application using a knapsack sprayer. Sprayings were carried out in the corn crop at the phenological stage V5–V6. The experiment consisted of three treatments and eight replications, applied with an RPA at heights of 1.5 and 3.0 m and a CO₂-pressurized knapsack sprayer. The application rate was 10 L ha⁻¹ for RPA and 115 L ha⁻¹ for the knapsack sprayer. Flat fan spray tips were used for all treatments. Tracer deposition in the corn canopy and spray loss to the soil were evaluated using spectrophotometric detection, while coverage, density, and droplet spectrum were evaluated on water-sensitive paper. Total and effective deposition swath were also evaluated for RPA. Although droplet density provided by RPA varied between 26 and 39 droplets cm⁻², the coverage was lower than 1.3%. Application using RPA at the height of 1.5 m provided tracer deposition on corn leaves similar to that carried out with the knapsack sprayer. The increase in application height to 3.0 m promoted a reduction in the deposition. Ground spraying promoted higher spray loss to the soil. The effective deposition swath consisted of 5.7 and 7.6 m for application heights of 1.5 and 3.0 m, respectively.