Development of fertilizer spreading mechanism for UAV-based fertilizer applicator

Efficient fertilizer application is vital for crop productivity, but conventional broadcasting is labor-intensive, time-consuming and often leads to uneven distribution, whereas UAVs offer a precise alternative. This study developed and evaluated a UAV-mounted spreading disc mechanism for urea application to improve distribution uniformity and optimize operational parameters. The system comprises a rectangular hopper (39° slope), a flow control unit, and interchangeable discs with 2–6 vanes. Laboratory trials followed a factorial design with flight height (1–3 m) and vane number (2–6), assessing fertilizer deposition using tray collectors and evaluating uniformity via coefficient of variation (CV). Deposition patterns were consistently right-skewed. Increasing vane number improved uniformity, reducing CV from 55.80% (2 vanes) to 38.21% (6 vanes). Higher flight height and lateral distance decreased uniformity, with CV increasing from 36.04% at 1 m to 56.03% at 3 m, and from 21.08% at 2 m to 70.83% at 20 m. Optimal performance occurred at 2 m flight height with 6 vanes, achieving a CV of 30.37% at 4 m lateral distance. The study demonstrates that UAV-mounted spreading disc mechanisms can effectively complement conventional ground equipment by enhancing efficiency and precision in fertilizer management.