Advancements in Variable Rate Spraying for Precise Spray Requirements in Precision Agriculture Using Unmanned Aerial Spraying Systems: A Review

Pesticides suppress pest populations and maintain agricultural yield; however, their overuse causes ecological damage. To mitigate the ecological damage caused by the overuse of pesticides, this paper explores the application of a precise and adaptable technique known as unmanned aerial spraying system (UASS)-based variable rate spraying (VRS). Herein, the current state of precision agriculture is examined, and the application of UASS in variable rate spraying is discussed. Then, the role of advanced sensors, including multispectral and hyperspectral technologies, in optimizing UASS-based VRS missions is studied, followed by the challenges in UASS-based spraying, ranging from technical intricacies to regulatory considerations, and related solutions. In addition to delving into pesticides, the paper explores alternative solutions such as herbicides, encompassing an integrated approach that aligns with sustainable farming practices for more effective pest management. VRS has advantages, including increased yields, reduced resource usage, and environmental sustainability. This paper concludes by delineating current challenges and envisioning future innovations, spotlighting ongoing studies on sensor technology and AI-driven flow rate optimization. This review provides insights into UASS-based VRS for precision agriculture.