## 2 Materials and Methods
### Sprayer Configurations and Spray Settings  
Table 1 gives an overview of the different configurations and settings tested for spray deposition and spray drift potential. For both deposition and drift potential measurements, the reference was considered to be a broadcast application of 158 l ha\({}^{-1}\), using a fixed nozzle spacing and height of 0.5 m with XR110 04 flat fan nozzles (TeeJet, Spraying Systems Co., Wheaton, IL USA) at a spray pressure of 300 kPa, without air support, and operated at 12 km h\({}^{-1}\). Figure 1: Prototype boom fitted with four nozzles. The bed spray configurations were selected based on spray distribution measurements carried out and described in [20]. Spray distribution measurements were performed for 13 nozzle configurations consisting of different nozzle types (conventional flat fan XR, air inclusion (AI) flat fan, off-center nozzles), nozzle size (ISO 02, ISO 04), spray angle (80\({}^{\circ}\), 110\({}^{\circ}\)), and number of nozzles (3 or 4 nozzles per bed). Per nozzle configuration, measurements were operated at an equal nozzle spacing and height ranging from 0.35 to 0.65 m. For six different target zone widths (ranging from 1.2 to 2.2 m with intervals of 0.2 m), the coefficient of variation (CV) in the target zone and the percentage of losses outside the target zone (%) of each configuration were determined. Four configurations, each consisting of four nozzles, met the criteria of low variability within the target zone (CV \(<\) 12%) and minimal losses out of the target zone (\(<\)17%) at the different target zone widths, when applied at the most appropriate nozzle spacing and height. These bed spray configurations consisted of four Teejet nozzles per configuration, i.e., XR8004/XR8004/XR8004/XR8004, XR8002/XR8002/XR8002, XR8004/AS004/AS004/AS004, AIUB8504/AI1004/AI1004/AIUB8504. All tests were performed at 300 kPa and 12 km h\({}^{-1}\), but depending on the configuration, the most appropriate nozzle spacing and boom height for the specific target zone width determined in [20] was used. The deposition measurements were carried out at two different growth stages, i.e., early-stage carrots and full-grown carrots, corresponding to respectively a target zone width of 1.4 m and 2.2 m. The boom height and nozzle spacing were adapted accordingly (0.4 or 0.45 m for the early-stage carrots and 0.6 m for the full-grown carrots). For drift potential measurements, 0.6 m boom height and nozzle spacing were used for the bed spray configurations to simulate the highest risk for drift generation. The spray deposition and drift potential of the bed spray configurations were tested at three different air support settings, i.e., no air support, air velocity of 4.0 m s\({}^{-1}\) and air velocity of 8.0 m s\({}^{-1}\) measured at the outlet of the air sleeve. In total, 13 settings were tested (Table 1). Each setting was replicated 3 times for deposition on carrots and spray drift potential. All experiments were achieved under a tunnel structure (Figure 1) of 24 m \(\times\) 8 m in order to limit the effect of wind conditions. Air temperature and humidity were measured under the tunnel at a height of 2 m above ground using a Vaisala HSM 110 sensor (Vantaa, Finland) directly