Air-assisted sprayer airflow interaction with traditional olive orchard canopies and its effect on spray distribution

• Airflow behavior inside traditional olive canopies was characterized under different sprayer gearbox settings. • LiDAR-derived point clouds of each tree provided accurate geometric data and allowed canopy density classification. • Application parameters strongly affected canopy air velocity attenuation, enabling accurate modeling of this variable. • Canopy areas associated with lower air velocity corresponded to lower spray coverage and deposition. Air-assisted sprayers currently incorporate mechanisms that allow modification of airflow outlet characteristics, which is a key factor in product distribution quality. However, limited information exists on how airflow interacts with complex tree canopies, particularly in traditional olive orchards. The aim of this study was to model the behavior of airflow velocity generated by a previously laboratory characterized air assisted sprayer in a traditional olive orchard, as a function of air flow configuration (fan gearbox) and operational and canopy structural parameters. Five olive trees were selected, and a three-dimensional grid of 64 measurement points (4 depths × 4 sections × 4 heights) was defined, where airflow velocity (m s −1 ) was recorded with a vane probe anemometer under two sprayer configurations. Canopy characterization was carried out using Light Detection and Ranging (LiDAR) measurements, from which both canopy volume (m 3 ) and density based on the number of impacts (NI) at each sampling location were determined. In addition, manual defoliations of 0.008 m 3 cubes were performed at 8 positions per canopy, allowing a correlation between impacts and leaf area density (LAD, m 2 m −3 ) to be established (R 2 = 0.61). Airflow within the canopy was characterized, and a model including sprayer gear setting, measurement depth, height, and categorized vegetation density (low or high density, LD or HD, respectively, based on the accumulated number of impacts across trees, NIa) explained 72% of the observed variability in air velocity inside the tree canopy. Spray performance was evaluated at the same sampling points using water-sensitive papers (WSP) and tracer collectors (manganese, Mn), allowing the effects of application parameters on coverage (%) and deposition (µg cm −2 ) to be quantified. These effects were largely consistent with those influencing air velocity, which was strongly correlated with both coverage and deposition. Notably, adequate coverage and deposition levels were predominantly associated with air velocities inside the canopy exceeding 2 m s −1 , providing valuable insight for optimizing sprayer adjustment and operating conditions.