## 3 Results and Discussion  
Consistent with the assumptions, droplet spectrum measurements demonstrated differences in droplet count and size between the two types of nozzles (Figures 3 and 4). At a liquid pressure of 0.40 MPa, the AP12003 sprayer produced finer droplets compared to the 6 MS03C sprayer. Figure 3: AP12003 sprayer’s droplet spectrum at a pressure of 0.40 MPa. Figure 2: Soybeans at harvest stage BBCH 89. Significant differences were found between both concentrations in plant coverage with the seaweed extract biostimulant (Table 1). Air-injector nozzle sprayers provided smaller plant coverage. Plants sprayed with tap water had a smaller liquid coverage compared to those sprayed with the biostimulant. Although no significant coverage differences were identified between concentrations, a higher biostimulant concentration could be seen to increase plant coverage. This is attributable to the reduced surface tension caused by the biostimulant's presence in the water. Significant differences in surface tension were identified between tap water and the mixture of water and seaweed biostimulant (Table 1). Differences were also noted in droplet area and droplet volume (not the dosed volume). The surface tension is a factor in the droplet spectrum, which, in turn, plays a role in plant coverage. The role of the surface tension, among other factors, in plant coverage was investigated by [PERSON] et al. [39]. They found that a reduction in the surface tension could increase plant wetness. [PERSON] et al. [40] came to a similar conclusion, demonstrating that the surface tension influenced plant wetness. The positive effects of the reducing surface tension noted in these studies have been corroborated by other studies [41], which found changes in droplet behaviour on the leaf surface, potentially improving plant coverage and distribution uniformity [42]. An important factor in the mechanical harvesting of soybean is the first pod height. Harvester-caused losses are smaller when the first pod is higher. The present study involving the application of a seaweed biostimulant with two types of spray nozzles revealed that both standard (AP12003) and air-injector (6 MS03C) nozzles had a positive effect on first pod height (Table 2). Although no significant differences in first pod height were found between the two types of nozzles, it was noted that, with standard-nozzle application, the height was 19% greater, on average, than with air-injector nozzle application. Studies by [PERSON] et al. [10] showed that first-pod height is influenced by plant height, probably due to the increased internode distances on the stem. [PERSON] et al. [43] had similar observations. They found that improved soybean height could be attributed to the application of biostimulants containing, among others, phenolic compounds. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Liquid**} & \multicolumn{3}{c}{**Physical Properties**} & \multirow{2}{*}{**Coverage [\%]**} \\ \cline{2-2} \cline{4-6}  & **Surface Tension** & & & & **AP12003** & **6 MS03C** \\ \cline{2-6}  & **(mN m\({}^{-1}\))** & **Area (mm\({}^{2}\))** & **Volume (\(\mu\)L)** & **AP12003** & **6 MS03C** \\ \hline Water & 71.46 \(\pm\) 0.84 a & 43.41 \(\pm\) 0.73 a & 28.83 \(\pm\) 0.67 a & 32.76 \(\pm\) 3.32 b & 22.56 \(\pm\) 2.31 b \\ Seaweed extract & 64.35 \(\pm\) 0.93 b & 38.62 \(\pm\) 0.69 b & 24.55 \(\pm\) 0.72 b & 65.79 \(\pm\) 4.92 a & 42.12 \(\pm\) 2.42 a \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Physical properties of the working liquid and plant coverage. Figure 4: 6 MS03C sprayer’s droplet spectrum at a pressure of 0.40 MPa. The two-year study described here has demonstrated that there is a significant correlation between the biostimulant application technique and plant height. Plants sprayed with the biostimulant using standard nozzles (AP12003) were 9 percent taller, on average, than plants sprayed using air-injector nozzles.