# Methods for Obtaining Humus Substances: Advantages and Disadvantages
## 3 Results and Discussion
### TGA Analysis  
Figures 2-4 present thermogravimetry (TG) curves of examined samples. Analysis of the HS(A) TG curve (Figure 2) shows that in the temperature range up to 200 \({}^{\circ}\)C, about 11% of the mass is removed. It is transitional and bound water and other volatile substances. At temperatures from 200 to 650 \({}^{\circ}\)C, 25% of the initial mass is lost due to the decomposition of simple aromatic compounds, hydrocarbons, carbohydrates, and functional groups [34; 35; 36; 37; 38]. The relatively large thermogradation of organic substances occurs at temperatures above 650 \({}^{\circ}\)C (up to 780 \({}^{\circ}\)C). Carbonates, such as iron and calcium carbonate, decompose at high temperatures. Mass loss in that temperature range is 27%. The amount of ash determined thermogravimetrically is relatively high (38.13%). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Element**} & \multicolumn{3}{c}{**Result**} & \multicolumn{3}{c}{**Result**} & \multirow{2}{*}{**Unit**} \\ \cline{2-2} \cline{4-9}  & **HS(A)** & & & & & & **HS(A)** & **HS(B)** & **HS(C)** \\ \hline Ag & - & \(<\)1 & - & La & - & 17 & - & mg/kg \\ \hline Al & 31 & 6443 & 2186 & Lu & - & \(<\)1 & - & mg/kg \\ \hline As & - & \(<\)1 & - & Mg & 150 & 1372 & 524 & mg/kg \\ \hline B & 202 & \(<\)1 & 20.5 & Mn & 165 & 47 & 21.67 & mg/kg \\ \hline Ba & 2 & 92 & 25.66 & Na & 1635 & \(<\)1 & - & mg/kg \\ \hline Be & - & \(<\)1 & - & Nd & - & \(<\)1 & - & mg/kg \\ \hline Ca & 992 & 23,800 & 5133 & Ni & - & 14 & 33.67 & mg/kg \\ \hline Cd & \(<\)1 & \(<\)1 & - & P & - & 209 & 29,222 & mg/kg \\ \hline Ce & \(<\)1 & \(<\)1 & - & Pb & - & \(<\)1 & 6.5 & mg/kg \\ \hline Co & 101 & \(<\)1 & - & Se & - & \(<\)1 & - & mg/kg \\ \hline Cs & - & \(<\)1 & - & Si & - & 2142 & - & mg/kg \\ \hline Cr & - & 15 & 31.67 & Sr & 6 & 143 & 28.67 & mg/kg \\ \hline Cu & 776 & 5 & 61 & Th & - & \(<\)1 & - & mg/kg \\ \hline Dy & \(<\)1 & \(<\)1 & - & Tl & - & \(<\)1 & - & mg/kg \\ \hline Er & \(<\)1 & \(<\)1 & - & Tm & - & \(<\)1 & - & mg/kg \\ \hline Eu & \(<\)1 & \(<\)1 & - & U & - & \(<\)1 & - & mg/kg \\ \hline Fe & 47 & 15,100 & 3991 & V & - & 22 & - & mg/kg \\ \hline K & 76,405 & 68,300 & 36,559 & Zn & 157 & 24 & 370.33 & mg/kg \\ \hline  & & & & Ash & 38.13 & 29.59 & 27.31 & \({}^{\circ}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Mineral components in HS(A), HS(B) and HS(C). Analysis of the HS(B) TG curve (Figure 3) shows that in the temperature range up to 200 \({}^{\circ}\)C, about 7% of the mass is removed. It is transitional and bound water and other volatile substances. Volatile organic substances are also removed at low temperatures (60-100 \({}^{\circ}\)C). In the temperature range of 200-650 \({}^{\circ}\)C, simple aromatic compounds, hydrocarbons, carbohydrates, and functional groups are decomposed, contributing to a 35% loss of the initial mass. Thermodegradation of organic substances occurs at temperatures above 650 \({}^{\circ}\)C (up to 780 \({}^{\circ}\)C), including calcium carbonates. This is indicated by the significant Ca content in the sample (23,800 mg/kg--Table 2). Other carbonates, such as iron carbonate, also decompose at high temperatures (Fe 15,100 mg/kg--Table 2). The amount of ash determined thermogravimetrically is 29.59%. Figure 3: Thermogravimetry (TG) curve of HS(B) sample. Figure 2: Thermogravimetry (TG) curve of HS(A) sample. Analysis of the HS(C) TG curve (Figure 4) shows that in the temperature range up to 200 \({}^{\circ}\)C, about 7% of the mass is removed. It is transitional and bound water and other volatile substances. At temperatures from 200 to 650 \({}^{\circ}\)C, simple aromatic compounds, hydrocarbons, carbohydrates, and functional groups are decomposed, causing a loss of 63% of the initial mass. The amount of ash determined thermogravimetrically is 27.31%. The results of TGA show that the HS(C) sample contains the highest amount of aromatic compounds, hydrocarbons, and carbohydrates (63%), followed by HS(B) with 33% and HS(A) with 25%.