## 5 Conclusions  
This pilot-scale experiment evaluated the effectiveness of different one-time biochar dose and bi-weekly reapplication on the mitigation of gaseous emissions from stored swine manure. The bi-weekly reapplication of the lower biochar dose (2 kg/m\({}^{2}\)) showed much higher significant percent reductions of emissions for NH\({}_{3}\) (33% without and 53% with reapplication) and skatole (42% without and 80% with reapplication), respectively. In addition, the reapplication resulted in the emergence of statistical significance to the mitigation effect for all other targeted VOCs. Specifically, for indole, the percent reduction improved from 38% (\(p\) = 0.47, without reapplication) to 78% (\(p\) = 0.018, with reapplication). For phenol, the percentage reduction improved from 28% (\(p\) = 0.71, without reapplication) to 89% (\(p\) = 0.005, with reapplication). For p-crresol, the percentage reduction improved from 31% (\(p\) = 0.86, without reapplication) to 74% (\(p\) = 0.028, with reapplication). For 4-ethyl phenol, the percent emissions reduction improved from 66% (\(p\) = 0.44, without reapplication) to 87% (\(p\) = 0.007, with reapplication). The one-time 2 kg/m\({}^{2}\) and 4 kg/m\({}^{2}\) treatments showed similar effectiveness in mitigating all targeted gases, and no statistical difference was found between the dosages. The one-time treatments showed significant percentage reductions of 33% and 42% and 25% and 48% for NH\({}_{3}\) and skatole, respectively. The practical significance is that the higher (one-time) biochar dose may not necessarily result in improved performance over the 8-week manure storage, but the bi-weekly reapplication showed significant improvement in mitigating NH\({}_{3}\) and odorous VOCs. The lower dosages and the frequency of reapplication on the larger-scale should be explored to optimize biochar treatment and bring it closer to on-farm trials. **Supplementary Materials:** The following are available online at [[https://www.mdpi.com/2073-4](https://www.mdpi.com/2073-4)]([https://www.mdpi.com/2073-4](https://www.mdpi.com/2073-4)) 433/12/1/96/s1, Table S1: Mitigation of NH3 emissions utilizing different treatments with HAP biochar. Different letters indicate statistical significance, Table S2: Mitigation of skatole peak area counts (PAC) utilizing different treatments of HAP biochar, Table S3: Mitigation of indole peak area counts (PAC) utilizing different treatments of HAP biochar, Table S4: Mitigation of phenol peak area counts (PAC) utilizing different treatments of HAP biochar, Table S5: Mitigation of p-crresol peak area counts (PAC) utilizing different treatments of HAP biochar, Table S6: Mitigation of 4-ethyl phenol peak area counts (PAC) utilizing different treatments of HAP biochar, Table S7: Mitigation of odor concentrations (OU/m\({}^{3}\)) utilizing different treatments with HAP biochar, Table S8: Mitigation of CO\({}_{2}\) emissions utilizing different treatments of HAP biochar, Table S9: Mitigation of CH\({}_{4}\) emissions utilizing different treatments of HAP biochar, Table S10: Mitigation of N\({}_{2}\)O emissions utilizing different treatments of HAP biochar. Figure S1: Mitigation of odor emissions from swine manure treated with biochar--effects of one-time dose (2 and 4 kg/m\({}^{2}\)) and 2 kg/m\({}^{2}\) bi-weekly reapplication, Figure S2: Mitigation of CO\({}_{2}\) emissions from swine manure treated with biochar--effects of one-time dose (2 and 4 kg/m\({}^{2}\)) and 2 kg/m\({}^{2}\) bi-weekly reapplication, Figure S3: Mitigation of CH\({}_{4}\) emissionsfrom swine manure treated with biochar--effects of one-time dose (2 and 4 kg/m\({}^{2}\)) and 2 kg/m\({}^{2}\) bi-weekly reapplication, Figure 54: Mitigation of N\({}_{2}\)O emissions from swine manure trated with biochar--effects of one-time dose (2 and 4 kg/m\({}^{2}\)) and 2 kg/m\({}^{2}\) bi-weekly reapplication. **Author Contributions**: Conceptualization, J.A.K. ; methodology, B.C., J.A.K. ; validation, J.A.K. and D.A. (manure analyses); formal analysis, B.C.