# Carbon Mineralization in a Soil Amended with Sewage Sludge-Derived Biochar
## 2 Materials and Methods
### Incubation Experiment
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Properties 1** & **Units** & **SS** & **BC300** & **BC400** & **BC500** \\ \hline C & \% & 21.0 \(\pm\) 0.4 & 23.4 \(\pm\) 0.4 & 21.6 \(\pm\) 0.3 & 19.0 \(\pm\) 0.2 \\ OC \({}^{\mathrm{a}}\) & Mebius & \% & 20.1 \(\pm\) 0.5 & 20.0 \(\pm\) 0.4 & 19.0 \(\pm\) 0.4 & 17.6 \(\pm\) 0.3 \\ OC \({}^{\mathrm{b}}\) & W\&B & \% & 14.0 \(\pm\) 0.4 & 14.5 \(\pm\) 0.5 & 13.9 \(\pm\) 0.4 & 13.3 \(\pm\) 0.4 \\ N & \% & 3.0 \(\pm\) 0.1 & 3.3 \(\pm\) 0.1 & 2.9 \(\pm\) 0.1 & 2.3 \(\pm\) 0.1 \\ H & \% & 4.2 \(\pm\) 0.1 & 3.6 \(\pm\) 0.1 & 2.7 \(\pm\) 0.2 & 1.7 \(\pm\) 0.1 \\ C/N & & 7.0 \(\pm\) 0.1 & 7.0 \(\pm\) 0.1 & 7.4 \(\pm\) 0.3 & 8.3 \(\pm\) 0.1 \\ H/C & & 2.4 \(\pm\) 0.1 & 1.8 \(\pm\) 0.1 & 1.5 \(\pm\) 0.2 & 1.1 \(\pm\) 0.1 \\ pH & & 4.8 \(\pm\) 0.4 & 5.8 \(\pm\) 0.2 & 6.5 \(\pm\) 0.4 & 6.5 \(\pm\) 0.3 \\ P & g kg\({}^{-1}\) & 35.7 \(\pm\) 2.8 & 41.1 \(\pm\) 3.2 & 53.7 \(\pm\) 5.0 & 61.3 \(\pm\) 5.6 \\ K & g kg\({}^{-1}\) & 0.8 \(\pm\) 0.1 & 1.6 \(\pm\) 0.1 & 1.08 \(\pm\) 0.1 & 1.25 \(\pm\) 0.1 \\ N-NO\({}_{3}\)\({}^{-}\) & mg kg\({}^{-1}\) & 23.3 \(\pm\) 3.4 & 17.5 \(\pm\) 2.8 & 5.84 \(\pm\) 1.0 & 5.8 \(\pm\) 0.9 \\ N-NH\({}_{4}\)\({}^{+}\) & mg kg\({}^{-1}\) & 461.2 \(\pm\) 36.0 & 431.9 \(\pm\) 31.0 & 198.5 \(\pm\) 8.0 & 169.3 \(\pm\) 19.8 \\ Ca & g kg\({}^{-1}\) & 6.6 \(\pm\) 0.1 & 6.7 \(\pm\) 0.2 & 7.1 \(\pm\) 0.4 & 8.2 \(\pm\) 0.3 \\ Mg & g kg\({}^{-1}\) & 0.8 \(\pm\) 0.1 & 1.8 \(\pm\) 0.1 & 1.7 \(\pm\) 0.2 & 1.7 \(\pm\) 0.1 \\ S & kg kg\({}^{-1}\) & 6.7 \(\pm\) 0.2 & 15.1 \(\pm\) 1.0 & 9.6 \(\pm\) 0.8 & 7.4 \(\pm\) 0.4 \\ Total Cu & mg kg\({}^{-1}\) & 115 \(\pm\) 1 & 148 \(\pm\) 1 & 147 \(\pm\) 2 & 145 \(\pm\) 1 \\ Total Pb & mg kg\({}^{-1}\) & 207 \(\pm\) 1 & 256 \(\pm\) 3 & 260 \(\pm\) 8 & 265 \(\pm\) 1 \\ Total Zn & mg kg\({}^{-1}\) & 306 \(\pm\) 1 & 321 \(\pm\) 1 & 368 \(\pm\) 4 & 411 \(\pm\) 5 \\ Total Cr & mg kg\({}^{-1}\) & 100 \(\pm\) 1 & 106 \(\pm\) 2 & 122 \(\pm\) 5 & 136 \(\pm\) 1 \\ Total Co & mg kg\({}^{-1}\) & 20 \(\pm\) 1 & 22 \(\pm\) 1 & 24 \(\pm\) 2 & 25 \(\pm\) 1 \\ Total Mn & mg kg\({}^{-1}\) & 56 \(\pm\) 1 & 58 \(\pm\) 1 & 68 \(\pm\) 4 & 80 \(\pm\) 2 \\ Moisture \({}^{\mathrm{c}}\) & g g\({}^{-1}\) & 0.17 \(\pm\) 0.01 & 0.004 \(\pm\) 0.001 & 0.003 \(\pm\) 0.001 & 0.003 \(\pm\) 0.001 \\ SSA \({}^{\mathrm{d}}\) & m\({}^{2}\) g\({}^{-1}\) & 18.2 \(\pm\) 1.2 & 20.2 \(\pm\) 1.8 & 29.85 \(\pm\) 2.1 & 52.5 \(\pm\) 4.3 \\ PV \({}^{\mathrm{e}}\) & mL g\({}^{-1}\) & 0.022 \(\pm\) 0.001 & 0.027 \(\pm\) 0.001 & 0.046 \(\pm\) 0.003 & 0.053 \(\pm\) 0.002 \\ Ash & g g\({}^{-1}\) & 0.54 \(\pm\) 0.03 & 0.59 \(\pm\) 0.02 & 0.68 \(\pm\) 0.2 & 0.79 \(\pm\) 0.04 \\ Yield & \% & - & 86 \(\pm\) 8 & 75 \(\pm\) 5 & 65 \(\pm\) 4 \\ \hline \hline \end{tabular}  
* Average values \(\pm\) standard deviation (\(n=3\)); \({}^{\mathrm{a}}\) organic carbon – Mebius procedure; \({}^{\mathrm{b}}\) organic carbon – Walkley–Black procedure; \({}^{\mathrm{c}}\) moisture content (65 \({}^{\circ}\)C); \({}^{\mathrm{d}}\) specific surface area; \({}^{\mathrm{e}}\) pore volume; SS: sewage sludge; BC300: biochar produced at pyrolysis temperature of 300 \({}^{\circ}\)C; BC400: biochar produced at pyrolysis temperature of 400 \({}^{\circ}\)C; BC500: biochar produced at pyrolysis temperature of 500 \({}^{\circ}\)C.  
\end{table} 
Table 2: Chemical, physical, and microbiological characteristics of the sewage sludge and biochars. lasted for 127 days in the dark at \(23\pm 2\)\({}^{\circ}\)C, and the alkaline trap was collected, titrated, and renewed fifteen times. Deionized water was used to bring all soils to 75% water holding capacity, and this was adjusted weekly. In the first 10 days, the trap was collected every two days, whereas, after that period, the trap was exchanged every seven days. The C mineralization rate (CMR) was determined during the sample incubation period.