## 3 Results and Discussion
The type of the binder does not significantly affect the amount of the commercial fraction. Figure 1: Cont. The groundometric composition of the granulated product is directly related to two other parameters, \(d_{50}\) or SGN, which are usually called the characteristics of the granulated fertiliser. SGN measurements are essential when creating a bulk blend; however, they are important for all granular products, as these numbers indicate the uniformity of the fertiliser granules. Fertilisers (for bulk-blended fertilisers) with SGNs that have no more than a difference of 10 [61] are preferred because, as the difference in SGN increases, the unevenness of the fertiliser particle size increases, which leads to a high risk of product segregation during storage and spreading. In this study, these parameters (\(d_{50}\) and SGN) were also calculated and the SGNs of different samples are presented in Table 1.  
The obtained data show that not all cases produce enough granular product to calculate the SGN. An insufficient marketable fraction may be the result of using too little or too much binder. The difference between the SGNs of the fertiliser (Table 1) compositions VI and VIII (MS binder) is not great (less than 20) and it can be expected that spreading such fertilisers will be successful enough. However, in compositions V and VII (BE binder), the SGN difference is large (50-59), which means that the amount of BE has a significant influence on the granulometric composition. In this case, it is necessary to ensure a very homogeneous mixing of the raw materials before the mixture reaches the granulator. The moisture content of the raw material mixtures prepared for granulation, as well as the physical properties of the granular product after drying at 80 \({}^{\circ}\)C to a constant mass, are presented in Table 2. These results, calculated with a 95% probability and standard deviation (\(\pm\)SD), are presented with each average value to provide an estimate of the variation in the data. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**Composition V**} & \multicolumn{4}{c}{**Composition VI**} & \multicolumn{4}{c}{**Composition VII**} & \multicolumn{4}{c}{**Composition VIII**} \\ \hline
1 & 2 & 3 & 4 & 5 & 6 & 7 & 8 & 9 & 10 & 11 & 12 & 13 & 14 & 15 & 16 \\
192 & 181 & 231 & – & – & 170 & 166 & – & – & 177 & 187 & 236 & – & 241 & 259 & 257 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: SGN values of biofertiliser samples. Figure 1: Dependence of the granululometric composition and the amount of the commercial fraction on the moisture content and composition of the raw material mixture: (**a**) composition V; (**b**) composition VI; (**c**) composition VII, and (**d**) composition VIII. The arrow shows on which axis the data is presented. Since the commercial fertiliser fraction does not consist of granules of one particular size, it is important to know whether products of different sizes have the same, very similar, or different properties. To evaluate this, granules from two fractions (2-3.15 mm and 3.15-4 mm) were analysed. As can be seen from the data in Table 2, in cases where the moisture content of the raw material mixture is between 31 and 36%, more granules with a size of 2-3.15 mm are formed. However, when the moisture content of the raw material mixture is higher than 36%, larger granules are formed, i.e., 3.15-4 mm in size (samples 4 and 8). This ratio between smaller and larger granules is not very favourable when evaluating the product in terms of static strength, because the 3.15-4 mm granules have higher strength. For example, in composition V, the strength of smaller granules varies between 7.89 and 9.71 N/granule, and in case of the larger ones, strength values fall into the interval of 8.50-13.46 N/granule; in composition VII, strength values range between 7.92 and 11.84 N/granule and 10.94-15.57 N/granule, respectively. It should be noted that the strength of the granules also depends on their composition.