## 3 Results and Discussions
### Sulfur Compounds  
Daily DMS emissions, averaged over the entire experimental period, were measured as 7.1 \(\pm\) 0.8 mg m\({}^{-2}\) day\({}^{-1}\) for the control, 3.3 \(\pm\) 0.3 mg m\({}^{-2}\) day\({}^{-1}\) for the 5% biochar treatment, and 1.8 \(\pm\) 0.2 mg m\({}^{-2}\) day\({}^{-1}\) for 10% biochar treatment, showing reductions of 53.1% and 74.5% for the 5% and 10% biochar treatments, respectively, compared to the control (\(p<\) 0.05, Table 6). While adding rice husk biochar significantly reduced DMS emissions, it had no apparent impact on H\({}_{2}\)S, MM, or DMDS levels. [PERSON] and [PERSON] (2018) reported that amine-modified chicken manure biochar exhibited an adsorption capacity of about 1.1 mg g\({}^{-1}\) for DMS in an aqueous solution. In addition, it was found that DMS accounted for about 82-97% of the total sulfur compound emissions in the experimental groups. [PERSON] et al. (2018) reported that H\({}_{2}\)S and DMDS were not detected during composing of cattle manure, while MM and DMS were continuously detected over 55 days. [PERSON] et al. (2018) identified that DMS and acetone emitted from dairy cattle manure accounted for about 60% and 90% of the total volatile organic compounds emitted from feces and urine, respectively. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \multirow{2}{*}{**Compound**} & \multirow{2}{*}{**Period**} & \multirow{2}{*}{**Control**} & \multicolumn{2}{c}{**Treatment**} & \multicolumn{2}{c}{\(p\)**-Value**} \\ \cline{3-8}  & & & **5\% Biochar** & **10\% Biochar** & & **5\% Biochar** & **10\% Biochar** \\ \hline H\({}_{2}\)S & 1 st week & 0.0 & 11.4 & 3.4 & 0.51 & 0.415 & 0.913 \\ (\(\mu\)g m\({}^{-2}\) & 2 nd week & 0.7 & 2.7 & 3.3 & 0.07 & 0.214 & 0.112 \\ day\({}^{-1}\)) & 3 rd week & 43.0 & 35.1 & 27.2 & 1.12 & 0.903 & 0.678 \\  & Overall & 8.0 & 13.3 & 7.7 & 5.08 & 0.575 & 0.998 \\ MM & 1 st week & 287.2 & 805.8 & 660.7 & 191.76 & 0.079 & 0.206 \\ (\(\mu\)g m\({}^{-2}\) & 2 nd week & ND \({}^{\dagger}\) & ND & ND & - & - & - \\ day\({}^{-1}\)) & 3 rd week & ND & ND & - & - & - \\  & Overall & 156.6 & 439.6 & 360.4 & 104.59 & 0.079 & 0.206 \\ DMS & 1 st week & 12.2 & 5.6 & 3.0 & 0.78 & 0.004 & \textless{}0.001 \\ (mg m\({}^{-2}\) & 2 nd week & 1.4 & 0.9 & 0.4 & 0.11 & 0.007 & \textless{}0.001 \\ day\({}^{-1}\)) & 3 rd week & 0.2 & 0.1 & 0.1 & 0.02 & 0.876 & 0.606 \\  & Overall & 7.1 & 3.3 & 1.8 & 0.42 & \textless{}0.001 & \textless{}0.001 \\ \hline \end{tabular}
\end{table} 
Table 6: Weekly variations in average emissions of sulfur compounds. Throughout the experimental period, the reduction effect on daily DMS emissions by rice husk biochar was observed up to the second week in both 5% and 10% biochar treatments (Table 6). The reduction rates of daily DMS emissions during the first week were 54.1% for the 5% biochar treatment and 75.0% for the 10% biochar treatment, while the DMS reduction rates in the second week were 37.6% in the 5% biochar treatment and 69.5% in the 10% biochar treatment, compared to the control (\(p<0.05\)). While the reduction effect diminished from the third week onward, the significant decrease in DMS emissions during the first and second weeks contributed substantially to the overall mitigation effect. Approximately 79% of the total DMS emissions from the control were released within the first three days of the experiment. During the same period, around 58-59% of the total DMS emissions from the 5% biochar treatment and 10% biochar treatment were emitted. The lower DMS emissions in the treatment groups were attributed to the better maintenance of aerobic conditions in the treatment groups compared to the control. During this period, oxygen concentrations in the control remained below 5% (1.7-4.9%) for two consecutive days, indicating anaerobic conditions [46]. In contrast, the treatment groups experienced oxygen levels below 5% for only one day during the same period, with levels reaching 1.6 \(\pm\) 0.1% in the 5% biochar treatment and 1.4 \(\pm\) 0.1% in the 10% biochar treatment (Figure 3).