## 3 Results
### Microbial Community Structure  
The abundance of bacterial 16S rRNA gene is reported Table 7 and ranged between 1.3 \(\times\) 10\({}^{10}\) and 7.6 \(\times\) 10\({}^{9}\)\(\pm\) 7.2 \(\times\) 10\({}^{8}\) copy dry soil g\({}^{-1}\) (soil added with 10% biochar). The relative abundance of nitrifying, denitrifying, and methanotrophic microbial groups showed significant differences due to treatment (Table 8), although a direct relationship between bacterial abundance and treatment is not clearly evident. The addition of digestate significantly increased methanogenic archaeal abundance, with the mcrA gene copy number being 42-64 times higher in soils treated with digestate, with or without biochar, and approximately two times higher in soils treated with biochar only, compared to control soil. Similarly, the addition of digestate led to a 15-22 times increase in 16S rRNA gene copy number from cluster IV Clostridaceae compared to control soil. Clostridiaceae from clusters I and II resulted 2.5-4 times higher in soil samples added with digestate only compared to control soil. Conversely, a drastic reduction in the specific 16S rRNA gene copy number was observed in soil samples where biochar was added at both 2% and 10% (Table 8). \begin{table}
\begin{tabular}{c c c c} \hline
**Treatment** & **CO\({}_{2}\)** & **CH\({}_{4}\)** & **N\({}_{2}\)O** \\ \hline Control & 3.30 (0.7) c & \(-\)0.30 (0.02) c & 0.53 (0.12) d \\ Dig1 & 4.97 (0.8) bc & \(-\)0.26 (0.04) c & 2.79 (0.27) cd \\ Dig2 & 3.97 (0.1) bc & \(-\)0.15 (0.01) b & 2.99 (0.10) cd \\ Bio2\% & 7.79 (1.4) b & \(-\)0.16 (0.01) b & 1.88 (0.57) cd \\ Bio10\% & 1.44 (0.1) c & \(-\)0.13 (0.01) b & 9.48 (2.1) b \\ Dig1+bio2\% & 17.98 (2.8) a & \(-\)0.11 (0.01) b & 3.97 (0.19) c \\ Dig2+bio2\% & 16.30 (3.2) a & \(-\)0.14 (0.01) b & 3.63 (0.69) c \\ Dig1+bio10\% & 1.56 (0.1) c & \(-\)0.02 (0.01) a & 13.65 (2.33) a \\ Dig2+bio10\% & 1.63 (0.3) c & \(-\)0.03 (0.01) a & 13.16 (1.94) a \\ \hline \end{tabular}
\end{table} 
Table 6: [PERSON]’s LSD post hoc test (\(p<0.05\)) of cumulative emissions of CO\({}_{2}\), CH\({}_{4}\) and N\({}_{2}\)O. Mean values of each flux are reported (standard error in parenthesis). Different letters indicate significant differences among treatments. \begin{table}
\begin{tabular}{c c} \hline
**Treatment** & **Total Bacteria** \\ \hline Control & 8.6 \(\times\) 10\({}^{9}\) (6.1 \(\times\) 10\({}^{8}\)) bc \\ Dig1 & 1.1 \(\times\) 10\({}^{10}\) (1.1 \(\times\) 10\({}^{9}\)) ab \\ Dig2 & 1.3 \(\times\) 10\({}^{10}\) (2.5 \(\times\) 10\({}^{8}\)) a \\ Bio2\% & 1.1 \(\times\) 10\({}^{10}\) (5.1 \(\times\) 10\({}^{8}\)) abc \\ Bio10\% & 7.6 \(\times\) 10\({}^{9}\) (7.2 \(\times\) 10\({}^{8}\)) c \\ Dig1+bio2\% & 1.3 \(\times\) 10\({}^{10}\) (1.6 \(\times\) 10\({}^{9}\)) a \\ Dig2+bio2\% & 1.1 \(\times\) 10\({}^{10}\) (1.1 \(\times\) 10\({}^{9}\)) ab \\ Dig1+bio10\% & 1.3 \(\times\) 10\({}^{10}\) (2.4 \(\times\) 10\({}^{9}\)) a \\ Dig2+bio10\% & 9.2 \(\times\) 10\({}^{9}\) (4.7 \(\times\) 10\({}^{8}\)) bc \\ \hline \end{tabular}
\end{table} 
Table 7: Absolute quantification of total bacteria expressed as 16S rDNA gene copy number g soil\({}^{-1}\) (standard errors in parenthesis). Different letters indicate significant differences at \(p<0.05\) ([PERSON]’s least Significant Difference, LSD). Bio, biochar; Dig1, digestate from reactor 1; Dig2, digestate from reactor 2.