## 4 Conclusions  
All the analysed industrial wastes from food production--buckwheat biomass (BBM), buckwheat husks (BH), buckwheat husks (BH), buckwheat husk ash (BHA), bone meals (BMs) from animal by-products, molasses solution (MS), and beaten eggs (BE)--are suitable for use in the production of organic biofertilisers. The moisture content of the raw material mixture significantly influences the size distribution of granules. At a moisture level of 32-35%, 57-68% of the produced biofertilisers are of the commercial fraction (2-4 mm size). A lower amount of BHA in the raw material mixture requires more binder to obtain a higher commercial fraction; however, of the type of binder does not affect this outcome.  
SGN values are a key parameter in the uniformity of the products. Depending on the composition and the binder used, SGN values range across wider or narrower intervals. When MS is used, SGN values are less than 20, and when BE is used, the differences between SGA values are large (up to 60). Variations were observed using the BE binder, requiring the homogenization of the raw material mixture prior to granulation.  
Larger granules exhibit higher static strength values (7.89-13.46 N/granule) compared to smaller ones (7.92-15.57 N/granule). Adding bone meal (BM) enhances the strength of all granules, indicating its significant contribution to the product's mechanical properties; meanwhile, the choice of binder has minimal impact on granule strength.  
The moisture content of organic fertilisers slightly exceeds the acceptable 3% norm for mineral NPK fertilisers, but the product remains stable for a long time (up to 8 months) when stored in ambient conditions.  
Spherical granules were produced in all cases, but those produced with BE binders exhibit more angularity and irregularities, which could be due to the heterogeneous nature of the binder. SEM-EDS analysis confirms that produced with BE binder granules are spherical yet angular with rough surfaces, while those made with MS binders are rounder and more uniform.  
Analysis of EDS maps reveals an even distribution of elements on the fertiliser surface, with carbon, oxygen, potassium, calcium, sulphur, and phosphorus among the main elements identified. Fertilisers containing higher BHA content have a lower carbon (\(\sim\)25-30%) concentration but they are richer in potassium (\(\sim\)22-26%). Chemical analysis indicates nitrogen (N\({}_{\rm total}\)) concentrations ranging from 3.56% to 4.73%, phosphorus (P\({}_{2}\)O\({}_{5}\)) concentrations ranging from 4.26% to 6.23%, potassium (K\({}_{2}\)O) concentrations ranging from 6.47% to 12.37%, calcium (CaO) concentrations ranging from 2.10% to 3.85%, and magnesium (MgO) concentrations ranging from 1.13% to 2.06%.  
Such fertilisers can be used in acidic soil, as their 10% solution has pH values of 9-10.  
Conceptualization, R.S.; methodology, O.P.; formal analysis, O.P.; data curation, O.P. and R.S.; writing--original draft preparation, O.P. and R.S.; writing--review and editing, R.S. and O.P.; visualization, O.P. and R.S.; supervision, R.S. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The raw data supporting the conclusions of this article will be made available by the authors on request.  
The authors declare no conflicts of interest.