## 3 Results and Discussions
### Ammonia  
The control emitted 178.3 \(\pm\) 7.5 mg m\({}^{-2}\) day\({}^{-1}\) of NH\({}_{3}\), while the 5% biochar treatment and 10% biochar treatment emitted 130.8 \(\pm\) 24.1 mg m\({}^{-2}\) day\({}^{-1}\) and 101.7 \(\pm\) 4.5 mg m\({}^{-2}\) day\({}^{-1}\), respectively, representing reductions of 26.6% and 43.0% compared to the control (\(p\) < 0.05, Table 5). Dividing the entire experimental period into weekly intervals, the effect of rice husk biochar in reducing daily NH\({}_{3}\) emissions was observed only up to the first week in the 5% biochar treatment and up to the second week in the 10% biochar treatment (Table 5). The reduction rates of NH\({}_{3}\) emissions in the first week were 30.9% in the 5% biochar treatment and 45.6% in the 10% biochar treatment, while the average NH\({}_{3}\) reduction rate in the second week for the 10% biochar treatment was 38.9% (\(p\) < 0.05). At the start of the experiment, the total nitrogen (TN) content on a dry basis was 2.1 \(\pm\) 0.0%. By the end of the experiment, the TN content was 1.4 \(\pm\) 0.1% for the control, 1.6 \(\pm\) 0.1% in the 5% biochar treatment, and 1.7 \(\pm\) 0.1% in the 10% biochar treatment. These values represent reductions of 31.7 \(\pm\) 4.5% in the control, 20.7 \(\pm\) 6.8% in the 5% biochar treatment, and 15.1 \(\pm\) 2.7% in the 10% biochar treatment (\(p\) < 0.05). This indicates higher TN retention in the treatment groups compared to the control. The effect of biochar on reducing NH\({}_{3}\) volatilization and retaining nitrogen in bedded packs results from its ability to adsorb ammoniacal nitrogen onto its surface [31; 32]. Similar findings have been reported in previous studies, demonstrating the effectiveness of biochar in reducing nitrogen losses and enhancing nitrogen retention during composting. [PERSON] et al. [33] observed that adding 2-10% bamboo biochar to poultry manure significantly reduced nitrogen losses, with NH\({}_{3}\)-N emissions decreasing from 47.8% in the control group to 38.7-10.8% in the biochar treated groups. Similarly, TN losses were reduced from 53.5% in the control group to 43.7-12.6% in the biochar treatments. [PERSON] et al. [34] reported that the addition of 10% rice straw biochar resulted in a final compost TN content of 2.2% (dry basis) in the treatment group, compared to 1.9% in the control. These studies collectively support the findings of the present study, indicating that biochar supplementation can effectively mitigate nitrogen losses and improve nitrogen retention during organic waste management. However, although direct comparisons are challenging because the odor reduction effectiveness of biochar can vary depending on factors such as its feedstock, the matrix to which it is applied, the application method, and any pretreatment [35; 36; 37; 38; 39; 40], the 10% biochar treatment group exhibited a slightly lower NH\({}_{3}\) reduction effect compared to those observed in previous studies. [PERSON] et al. [4] found that adding 10% green waste biochar or poultry litter biochar to a poultry litter and straw composting mixture reduced ammonia emissions by 58% and 38%, respectively, while increasing nitrogen retention in the finished compost to 84% and 78%, compared to 67% in the control. [PERSON] et al. [5] also demonstrated that the addition of modified cornstalk biochar reduced NH\({}_{3}\) emissions by 46-62% during the composting of layer manure. This difference in NH