Optimizing Air-Assistance for an Electrostatic Sprayer Integrated with Intelligent Spray Control in a Greenhouse Environment

• Air-assisted electrostatic spraying increased canopy deposition by up to 302.7%. • An air-blower velocity of 10 m s -1 maximized performance in low-wind environments. • Air-assisted electrostatic spraying improved greenhouse coverage by up to 49.1%. • Variable-rate electrostatic spraying resulted in deep canopy penetration. • Intelligent systems achieved superior uniformity while reducing agrochemical waste. An air-assisted electrostatic spraying system was optimized in a wind tunnel across a range of air-blower speeds and electrostatic charging conditions, and the optimized configuration was subsequently evaluated in a full-scale greenhouse environment. Wind tunnel results showed that under still-air conditions, an air-blower speed of 10 m s -1 optimized charge-to-mass ratio (CMR) and spray performance, achieving a peak average canopy coverage of 15.4% and deposition of 1.52 µg cm -2 . Under moderate wind conditions of 2.24 m s -1 , the optimal operational parameters shifted; maximum canopy deposition was observed at an air-blower speed of 15 m s -1 , while maximum coverage occurred at 20 m s -1 . Subsequent greenhouse experiments compared conventional and variable-rate ‘intelligent’ spraying systems, both with and without electrostatic charging, to quantify canopy coverage, spray uniformity, and overspray potential. Electrostatic charging enhanced average coverage by 21.5% and 26.8% for conventional and intelligent systems, respectively, compared to the non-electrostatic counterparts. When combined with air-assistance, electrostatic charging increased coverage by 49.1% for the conventional system and 35.5% for the intelligent variable-rate system relative to the conventional non-electrostatic system. Additionally, the intelligent system significantly improved the spray uniformity index and minimized overspray potential in the tested scenarios. These findings suggest that integrating intelligent variable-rate control with air-assisted electrostatic spraying shows promise for improving canopy penetration and reducing excessive upper-canopy deposition in greenhouse environments. Further validation against biological pest control endpoints is needed to confirm the agronomic significance of these improvements.