## 3 Results and Discussion
Analysis of the pH values of these organic biofertilisers shows that they are alkaline. A greater amount of BHA in the mixture of raw materials (compositions VII and VIII) increases their alkalinity from about 9.5 to 10.4. It is likely that such fertilisers could be used in acid soils and act as liming agents. Particle shape can vary among fertilisers and can be classified as round (spherical or egg-shaped), cubic, rectangular, or irregular. The shape can influence the behaviour of material during conveyance and fertilization. Round particles generally roll along and then roll off the spinner vanes. Irregularly shaped particles tend to slide along the vanes; here, the coefficient of friction is more influential on particle dynamics, such as exit velocity, than it is in the case of spherical particles [67]. In this case, irregularly shaped granules are spread on the soil surface less evenly than spherical ones. Therefore, the shape and homogeneity of fertilisers of different compositions were evaluated both visually (Figure 2) and by SEM-EDS methods (Figure 3). From the photos in Figure 2, it can be seen that the shape of the granules is spherical in all cases, but there are more angles and irregularities when the BE binder was used (composition V and VII). This can be explained by the fact that it was more complicated to mix raw materials, because BE itself is not in a homogeneous liquid phase. It is possible to draw the same conclusion from the results of the PGI analysis--it is necessary to ensure a very homogeneous mixing of the raw materials before they reach the granulator. Although the general shape of the biofertiliser granules can be seen from the photographs, a more accurate evaluation of the shape and homogeneity of the granules came from the SEM-EDS data. It can be seen from the presented SEM photographs that, when BE was used for agglomeration of dry raw materials (Figure 3a,c), the granules were spherical, but they were quite angular and their surface was rough, with cavities and bumps. Meanwhile, when MS was used as a binder (Figure 3b,d), the granules were round, and their surface was more uniform. These differences in granule shape and surface can be explained by the physical properties of the binder. BE is a heterogeneous system consisting of both liquid (egg yolk and protein) and solid (crushed eggshell) phases, so its uniform distribution among dry raw materials is problematic. MS, on the other hand, is a homogeneous solution that, after mixing, distributes itself evenly throughout the raw material mixture and fills the spaces between the particles without any problems. Analysing the EDS maps of elements, it can be seen that the elements are distributed quite evenly on the surface. The spectra show the same main elements arranged in an analogous sequence according to decreasing concentration: carbon, oxygen, potassium, calcium, sulphur, phosphorus, etc. However, the concentration of these elements varies in different samples. Fertiliser compositions VII and VIII, with higher BHA content, contain less carbon (\(\sim\)25-30%) but more potassium (\(\sim\)22-26%) compared with fertiliser compositions V and VI, with lower BHA content. Here, the carbon content is \(\sim\)32-38% and the potassium content is \(\sim\)8-10%. All the tested fertiliser samples contained 2-4% S, 4-6% Ca, and up to 3% Mg. However, it is very strange that nitrogen was not found when testing fertilisers using this method, although its concentration is not low and ranges from 3.56% to 4.73% when chemical analysis methods (Table 3) are applied.