## 3 Results and Discussion
Obviously, the auxiliary air stream does not have to be evenly distributed along the entire boom width when herbicides are applied to protect plants grown in widely spaced rows and to control inter-row weeds. Inter-row weeds should be mechanically controlled, although mechanical weeding does not eliminate intra-row weeds or weeds growing close to the plants inside the crop safety zone [1; 17]. Over-row sprayers where the position of the spray nozzles and air diffusers can be adjusted by the user are best-suited to these types of crop stands, and nozzles and diffusers should be positioned symmetrically above the spray band. Spray droplets have kinetic energy but they are swept along by a moving stream of air [3; 38]. Therefore, the airflow velocity should be kept constant across the entire spray band, unless the target crop has a growth habit that does not require such an approach. In this case, the airflow velocity in sectors with different plant densities should be adjusted to ensure that the liquid reaches the lowest segment of the stem [23]. However, if this factor is disregarded, protective treatments can be applied to strips with a width of up to 50 cm  
Figure 5: Comparison of air velocity distribution at two fan-speed settings measured at a distance of 20 cm from the diffuser outlet. when diffusers are positioned 10 cm above the ground, and this configuration is ideal for crops grown in strips with a width of up to 30 cm. The airflow velocity was equalized (no significant differences in the mean airflow velocity) when the diffusers were positioned at a minimum height of 30 cm (at 80 cm intervals) or 40 cm (at 90 cm intervals). In this case, the difference between the minimum  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Diffuser Height (cm)** & \begin{tabular}{c} **Distance** \\ **from the** \\ **Diffuser** \\ **Axis (cm)** \\ \end{tabular}  & \multicolumn{6}{c}{**Airflow Velocity (m s\({}^{-1}\))**} \\ \cline{3-8}  & **10** & 21.54 \(\pm\) 2.73 \({}^{\rm\,ab}\) & 19.29 \(\pm\) 6.44 \({}^{\rm\,a}\) & 21.89 \(\pm\) 4.53 \({}^{\rm\,a}\) & 25.85 \(\pm\) 4.55 \({}^{\rm\,a}\) & 22.84 \(\pm\) 6.76 \({}^{\rm\,a}\) & 24.64 \(\pm\) 7.34 \({}^{\rm\,a}\) \\ \hline \multirow{8}{*}{10} & 5 & 22.80 \(\pm\) 2.44 \({}^{\rm\,a}\) & 17.66 \(\pm\) 7.76 \({}^{\rm\,a}\) & 20.54 \(\pm\) 5.86 \({}^{\rm\,a}\) & 26.94 \(\pm\) 3.05 \({}^{\rm\,a}\) & 20.27 \(\pm\) 8.32 \({}^{\rm\,ab}\) & 24.79 \(\pm\) 7.42 \({}^{\rm\,a}\) \\  & 10 & 22.48 \(\pm\) 2.72 \({}^{\rm\,a}\) & 16.98 \(\pm\) 8.56 \({}^{\rm\,ab}\) & 19.16 \(\pm\) 4.40 \({}^{\rm\,a}\) & 26.68 \(\pm\) 4.36 \({}^{\rm\,a}\) & 19.59 \(\pm\) 9.57 \({}^{\rm\,ab}\) & 23.90 \(\pm\) 6.66 \({}^{\rm\,a}\) \\  & 15 & 20.48 \(\pm\) 5.36 \({}^{\rm\,ab}\) & 15.63 \(\pm\) 8.47 \({}^{\rm\,ab}\) & 16.30 \(\pm\) 1.37 \({}^{\rm\,ab}\) & 26.25 \(\pm\) 4.08 \({}^{\rm\,a}\) & 18.85 \(\pm\) 9.60 \({}^{\rm\,ab}\) & 23.84 \(\pm\) 6.19 \({}^{\rm\,a}\) \\  & 20 & 12.51 \(\pm\) 12.08 \({}^{\rm\,ab}\) & 13.11 \(\pm\) 7.84 \({}^{\rm\,ab}\) & 8.21 \(\pm\) 8.46 \({}^{\rm\,bc}\)  
and maximum airflow velocities at different distances from the diffuser axis could reach 50%. This could be attributed to the imprecise installation of the diffusers or the uneven distribution of air streams across the diffusers, but mainly to the insufficient overlap of air streams from adjacent diffusers. The uniformity of the spray distribution could be improved by increasing the boom height above the crop stand. For this reason, optimal spray-distribution uniformity at both fan speeds and at all diffuser intervals could be achieved when the boom and diffusers were positioned 50 cm above the crop stand. To minimize airborne spray drift, the boom height should not be increased [14; 26; 39]. The effects of the interactions between the nozzle and diffuser settings were analyzed in the next step of the study by positioning the diffusers at a height of 50 cm above the patternator.