Pesticide spray drift has been a worldwide concern in terms of potential environmental pollution and ecosystem damage. This study defined the main drift reduction agent (DRA) characteristics that help to understand the drift formation process in agricultural spraying. Seven various DRAs and water were evaluated. Three solutions were created based on the following materials: calcium dodecylbenzenesulfonate, benzenesulfonic acid, C10-13-alkyl derivatives, and calcium salt. Drift measurements were performed by means of the open circuit-type wind tunnel and in the field under conditionally controlled conditions. Air-injector flat spray nozzles and standard flat spray nozzles were used during trials. The spray pressure was 4.0 bar. Solutions were sprayed at different wind speeds (from 2 m s⁻¹ to 10 m s⁻¹, increasing every 2 m s⁻¹). Studies have shown that wind speed and nozzle design have the greatest influence on spray drift. For all DRA solutions studied, the standard flat spray nozzles resulted in ground spray drift, both in the wind tunnel and in the field, which was about two times higher than that of air-injector flat spray nozzles. The spraying of water and all DRA solutions with the air-injector flat spray nozzle showed that all new solutions statistically significantly reduced the drift both in the tunnel and in the field. Ground-drift studies in the wind tunnel showed a trend towards a less intense drift reduction in DRA droplets with increasing wind speed. With DRA7e, the drift can be reduced by up to 56% (at a wind speed of 4 m s⁻¹) and up to 30% (at 10 m s⁻¹). The effect of the solutions on the reduction in spray drift is significantly lower when spraying with standard flat spray nozzles. Spray drift can then be reduced by up to 30% (at a wind speed of 4 m s⁻¹) and up to 12% (at 10 m s⁻¹) for DRA7e.

During the spraying operation, it is important to consider the environmental conditions, particularly the wind velocity. Droplets carried by the wind out of the spray zone may be carried onto nearby plants, soil, water bodies, residential areas, etc. Various measures have been developed and used to reduce droplet drift to address this problem. Robotic spraying systems, such as unmanned aerial vehicles and spraying robots, are now increasingly being used. The influence of lateral winds on the spraying processes of these systems has not yet been extensively investigated. In this study, spray coverage and spray drift of manufactured artificial plants were investigated. Spraying was carried out with an XAG R150 spraying robot and a lateral wind from 2 m s⁻¹ to 8 m s⁻¹ was generated with an air flow generation stand by varying the air flow velocity every 2 m s⁻¹. Spray coverage on the artificial plants was measured at two heights (0.5 and 1 m). The droplet coverage measurements were significantly influenced by the lateral wind velocity and the height of the plant coverage measurement site. The results showed that even in the presence of a high lateral wind velocity (v = 6–8 m s⁻¹), the droplet spray had better coverage of the middle part of the artificial plant (0.5 m from the ground) than the upper part (1 m from the ground). For the spray drift studies, three solutions with low concentrations (0.1%) of chemical drift reduction agents (DRAs) were sprayed, with water as control. It was found that the proportion of drifting droplets also increased with increasing lateral wind velocity. The spray coverage at 3 m from the spray zone (spray drift) was 1.6% at a lateral wind velocity of v = 2 m s⁻¹, 4.2% at v = 4 m s⁻¹, 5.3% at v = 6 m s⁻¹, and 8.1% at v = 8 m s⁻¹. The use of DRAs was able to reduce spray drift in strong (v = 8 m s⁻¹) lateral winds. It was found that at 3 m from the spray zone, at a spray height of 1 m, the spray coverage was about 40.7% lower than that of water for DRA1, 44.4% for DRA2, and 43.2% for DRA3.

Perennial crop systems (e.g., orchards) require frequent spraying with plant protection products. Equipment plays a crucial role in assessing energy efficiency, productivity, economic performance, and the environmental impact of orchard production. In recent years some farmers have replaced conventional tractor-mounted air-blast sprayers (TMABS) and switched to unmanned ground vehicles (UGVs) or unmanned aerial vehicles (UAVs). However, there has been a lack of comparative studies on the energy and environmental assessment of these systems. This study aimed to evaluate the overall viability of different orchard spraying technologies in terms of energy efficiency, economic costs, and environmental impact. A life cycle assessment (LCA) of five sprayers was performed: a TMABS, a UGV, and three UAVs. The CML-IA methodology and SimaPro 9.5 software with the Ecoinvent v3 database were used to determine the environmental impact of the compared machines. Energy efficiency was calculated using fuel consumption data, human labor energy, and the energy embodied in the machinery. Economic viability was evaluated through capital depreciation, labor, energy consumption, consumable and maintenance cost per hectare calculation models. The results indicate that UAV systems, as compared to TMABS, can significantly reduce operational energy consumption, water use, and environmental impacts. The GWP of UAV systems was about 67% lower compared to the TMABS, while the UGV, due to lower performance efficiency, exhibited a 4% larger GWP (kg CO_2eq ha⁻¹). The findings of this study highlight that UAVs can produce the optimal results in comparison to other application methods.