## 2 Materials and Methods  
### Experimental Part  
Considering the chemical properties of the various waste, recipes for the material composition of four granulates with the participation of industrial sludge, lignite ash, sawdust, ammonium nitrate and potassium salt (60% K\({}_{2}\)O) were developed. For the production of sludge-ash granulates, the following were selected: industrial from the sewage treatment plant of the Chemical Plant Grupa \"Azoty\" in Police (53 deg34'26'' N, 14 deg32'42'' E in West Pomeranian Voivodeship, in Poland), ash from the combustion of lignite in a power plant \"Adamow\" S.A located in Konin (52 deg18'04.5'' N, 18 deg14'02.8'' E in Wielkopolska Voivodeship, in Poland) and a 1:1 mixture of sawdust from hardwood and coniferous trees from the sawmill in Pucice (53 deg27'13.107'' N, 14 deg44'39.194'' E in WestPomeranian Voivodeship, in Poland). The material composition of fertilizer granulates is given below:  
I granules--30% industrial sewage sludge, 30% ash, 10% sawdust, 15% ammonia phosphate, 15% potassium salt;  
II granules--40% industrial sewage sludge, 20% ash, 10% sawdust, 15% ammonia phosphate, 15% potassium salt;  
III granules--20% industrial sewage sludge, 40% ash, 10% sawdust, 15% ammonia phosphate, 15% potassium salt;  
IV granules--50% industrial sewage sludge, 20% ash, 10% sawdust, 10% ammonia phosphate, 10% potassium salt. The produced sediment-ash granulates were used for experiments. The plants tested were spring rape, _Larisa_ cv., and spring triticale, _Milikaro_ cv. The chemical analysis carried out indicates that the industrial sewage sludge had an alkaline reaction (8.60) and contained 28% dry matter (DM). It had little organic carbon content (2.10%) and nitrogen (2.40 g\(\cdot\)kg\({}^{-1}\) DM). The ash from the combustion of lignite was characterized by a strongly alkaline reaction (11.8) and a significant content of dry matter (98.0%). It did not contain organic carbon and nitrogen. Total contents of calcium (14.5 g\(\cdot\)kg\({}^{-1}\) DM), magnesium (1.75 g\(\cdot\)kg\({}^{-1}\) DM) and sulfur (4.20 g\(\cdot\)kg\({}^{-1}\) DM) in relation to the content of phosphorus (6.70 g\(\cdot\)kg\({}^{-1}\) DM) and potassium (1.20 g\(\cdot\)kg\({}^{-1}\) DM) were considerable. The mixture of sawdust from deciduous andiferous trees contained significant amounts of dry matter, organic carbon and nitrogen (5.90 g\(\cdot\)kg\({}^{-1}\) DM), and little phosphorus (0.39 g\(\cdot\)kg\({}^{-1}\) DM), potassium (0.45 g\(\cdot\)kg\({}^{-1}\) DM), calcium (0.90 g\(\cdot\)kg\({}^{-1}\) DM) and magnesium (0.96 g\(\cdot\)kg\({}^{-1}\) DM). The content of heavy metals in the waste used for the production of granulates is given in the Table 1.  
The content of heavy metals in the waste used to produce fertilizer granulates was low. The concentration level of these elements was below the permissible levels. Table 2 presents the content of heavy metals in the produced granulates. Whereas in Table 3, the doses of applied granulates to the soil are presented. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Metal**} & \multicolumn{3}{c}{**Waste**} \\ \cline{2-4}  & **Industrial Sewage Sludge** & **Brown Coal Ash** & **Sawdust Mixture** \\ \cline{2-4}  & \multicolumn{3}{c}{**Total Content in mg\(\cdot\)kg\({}^{-1}\) DM**} \\ \hline Cd & 0.82 & 1.95 & 0.16 \\ Cu & 22.0 & 25.6 & 4.25 \\ Cr & 8.85 & 12.5 & 1.60 \\ Ni & 13.8 & 12.0 & 0.80 \\ Pb & 52.0 & 14.2 & 2.30 \\ Zn & 120.0 & 220 & 38.4 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Content of heavy metals in waste used for the production of fertilizer granulates.