## 3 Results
### Soil Analysis in Pot Experiment  
Data for soil physical and chemical properties under different biochar treatments sampled after harvesting of rice plant at the heading stage (70 DAT) are presented in Tables 6-9. The total N in the soil was significantly higher in T2 and T3 compared with that in T0, T1, T4, and T5 (Table 6). However, there was no significant difference in soil total N among treatments amended with RSRH biochar (T2 and T3). Similarly, the results showed that there was no significant difference in the retention of NH4+ and N03- in between T2 and T3. Both treatments amended with RSRH biochar significantly increased the soil exchangeable NH4+ and N03- over the rest of the treatments.  
Figure 3: Ammonia volatilization over 28 days of incubation under waterlogged condition.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Treatments**} & **pH** & **NH4+** & **NO3-** & **Ammonia Loss** \\  & **(Water)** & **(ppm)** & **(ppm)** & **(\%)** \\ \hline T0 & 5.53 \(\pm\) 0.06 a & 106.67 \(\pm\) 12.01 a & 32.67 \(\pm\) 2.33 ab & 0.00 \(\pm\) 0.00 a \\ T1 & 6.23 \(\pm\) 0.12 b & 256.67 \(\pm\) 29.63 b & 37.67 \(\pm\) 1.86 ab & 46.29 \(\pm\) 1.79 de \\ T2 & 8.06 \(\pm\) 0.06 e & 500.1 \(\pm\) 2.06 d & 56.30 \(\pm\) 4.33 c & 30.79 \(\pm\) 0.11 bc \\ T3 & 7.95 \(\pm\) 0.02 de & 458.5 \(\pm\) 17.96 d & 56.00 \(\pm\) 4.04 c & 27.43 \(\pm\) 0.71 b \\ T4 & 7.88 \(\pm\) 0.02 de & 394.67 \(\pm\) 6.12 c & 46.33 \(\pm\) 2.19 bc & 32.62 \(\pm\) 1.20 c \\ T5 & 7.75 \(\pm\) 0.03 d & 289.33 \(\pm\) 6.17 b & 41.0 \(\pm\) 0.58 abc & 33.66 \(\pm\) 0.50 c \\ T6 & 7.38 \(\pm\) 0.03 c & 276.67 \(\pm\) 8.82 b & 30.33 \(\pm\) 4.98 a & 44.13 \(\pm\) 0.16 d \\ T7 & 7.36 \(\pm\) 0.07 c & 223.33 \(\pm\) 21.86 b & 30.34 \(\pm\) 2.33 a & 48.86 \(\pm\) 0.23 e \\ \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 5: Effect of treatments during ammonia volatilization study on soil pH, exchangeable NH4+, exchangeable NO3-, and ammonia loss.  
(\(p<0.05\)) increment in total organic matter and total C compared to other treatments (Table 7). In addition, treatments with RSRH biochar (T2 and T3) also significantly increased the soil CEC compared to other treatments (Table 8).  
The treatments with RSRH biochar (T2 and T3) significantly reduced the soil exchangeable acidity over T0, T1, T4, and T5 (Table 8). However, T2 and T3 did not reduced the soil exchangeable Al and Fe significantly in comparison to the soil alone (T0) and soil + urea (T1), but the RSRH-amended treatments reduced the soil exchangeable Al and Fe significantly compared to commercial biochar potting media (T4 and T5). Even though there was no significant reduction in Al and Fe in T2 and T3, nevertheless T2 and T3 had increased the soil available P significantly over the rest of the treatments (Table 8). Similar observations were observed in T2 and T3 for available K and Ca (Table 9). However, there was no significant difference in retention of available Mg and Zn in between all the treatments.