## 4 Discussion  
### Ammonia Volatilization Study  
The RSRH-amended biochars successfully minimized NH\({}_{3}\) volatilization by delaying by up to 6-7 days. The total loss of NH\({}_{3}\) in RSRH amended treatments was significantly low compared to the treatments without biochar and treatments with biochar potting media. The ability to minimize NH\({}_{3}\) lies in the nature of biochar. Biochars' porosity and \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Treatments** & **N Use Efficiency** & **P Use Efficiency** & **K Use Efficiency** \\ \hline T1 & \(15.17\pm 1.36\) \({}^{\text{a}}\) & \(0.013\pm 0.002\) \({}^{\text{a}}\) & \(8.52\pm 3.89\) \({}^{\text{a}}\) \\ T2 & \(56.59\pm 1.26\) \({}^{\text{b}}\) & \(0.17\pm 0.013\) \({}^{\text{b}}\) & \(97.07\pm 3.43\) \({}^{\text{b}}\) \\ T3 & \(53.08\pm 2.82\) \({}^{\text{b}}\) & \(0.15\pm 0.004\) \({}^{\text{b}}\) & \(87.57\pm 1.32\) \({}^{\text{b}}\) \\ T4 & \(14.45\pm 1.65\) \({}^{\text{a}}\) & \(0.03\pm 0.003\) \({}^{\text{a}}\) & \(46.70\pm 1.61\) \({}^{\text{a}}\) \\ T5 & \(10.68\pm 3.19\) \({}^{\text{a}}\) & \(0.02\pm 0.002\) \({}^{\text{a}}\) & \(42.03\pm 3.60\) \({}^{\text{a}}\) \\ \hline \hline \end{tabular} Mean values within column with different letter(s) indicate significant difference between treatments by [PERSON]’s test at \(p\leq 0.05\). Columns represent the mean values \(\pm\) SE.  
\end{table} 
Table 12: Effects of RSRH biochar on N, P, and K use efficiency at harvest (70 DAT). Figure 8: Effects of treatments on total Mg uptake at harvest (70 DAT). Mean values with different letter(s) indicate significant difference between treatments by [PERSON]’s test at \(p\leq 0.05\). Bars represent the mean values \(\pm\) SE. Figure 7: Effects of treatments on total Ca uptake at harvest (70 DAT). Mean values with different letter(s) indicate significant difference between treatments by [PERSON]’s test at \(p\leq 0.05\). Bars represent the mean values \(\pm\) SE. larger surface area increase the adsorption rate of NH4+ and NO3- ions and reduce the volatilization of NH3[35]. The dual characteristics of biochar enhanced the adsorption of both negatively and positively charged ions onto its exchange sites [36]. This was further supported by the findings in this study where the treatments amended with RSRH biochar, specifically 5 and 10 t han-1, retained more NH4+ and NO3- ions in the soil (Table 5). The increased NH4+ and NO3- ions in the soil might be related to the CEC of RSRH biochar which is >66.6 cmolc kg-1 (Table 4). The higher retention of nutrients might also be due to biochar that degrade very late and, as a result, the adsorbed nutrients being released slowly. [PERSON] et al. [37] reported that biochar in soil is very resilient and breaks down only sparingly over the long term; thus, captured nutrients are released slowly. In addition, biochar has significant carbonaceous components due to incomplete combustion of various organic components; hence, biochar remains in the soil long term [38; 39]. The presence of biochar for a long period of time in the soil, and the slow release process of the adsorbed nutrients increases the nutrients in the soil for plant uptake. The characteristic of RSRH biochar acting as a slow release fertilizer means it is able to minimize NH3 loss and benefit the plant. Moreover, biochar-amended treatments increased the soil pH. The pH of the soil amended with RSRH biochar (T2-T5) was significantly higher than the rest of the treatments. The soil pH increased during the period of the NH3 volatilization study may have been due to the inherent properties of biochar, which is alkaline in nature (>9) (Table 4). Previously, it was reported that NH3 volatilization is rapid in alkaline soils [40]. However, the results in this study showed lesser NH3 volatilization even though the soil was near neutral. This may have been due to the increased adsorption and conversion to NH4+ and NO3- over NH3. Additionally, [PERSON] [41] stated that the pH increase in soil amended with biochar was not high enough to enhance NH3 volatilization.