# Optimization of Blended Biochar Pellet by the Use of Nutrient Releasing Model
## 3 Results  
It was observed that the more biochar contained within the biochar pellet, the greater sorption of NH\({}_{4}\)-N. For accumulated NH\({}_{4}\)-N releasing amount, the order was PMC > PMC > BCP (2:8) > BCP (4:6) > BCP (8.2) > BCP (9:1) ratios, and the highest accumulated amount in the PMC was 397 mg L\({}^{-1}\) (Figure 2). The estimation parameters for an accumulated NH\({}_{4}\)-N releasing amount from different types of biochar pellets are presented in Table 2. The model was significantly correlated with the \(R^{2}\) values between the observed and estimated values. The maximum accumulated NH\({}_{4}\)-N releasing amount was observed in PMC even if same amount of pig manure compost between PMC and PMCP was used in the leaching column. This might be due to the increase mass of pig manure compost. However, the required time to reach half of the maximum accumulated amount in PMC was taken only 16 at days, but was 41 days in PMCP. Therefore, pelletization could reduce the releasing rates of NH\({}_{4}\)-N even if the same loading amount of material was used. The greater accumulated amount and longer leaching periods were observed in the BCP (2:8 and 4:6). The estimated releasing model was significantly fitted with all treatments (Table 2). The accumulated amount of PO\({}_{4}\)-P was not significantly different with biochar pellets which contained 0 to 40% of biochar during leaching periods. It was shown that the highest accumulated amount of PO\({}_{4}\)-P in the PMC was 1953 mg L\({}^{-1}\) and the lowest in the BCP (9:1 ratio) was 223 mg L\({}^{-1}\) (Figure 3). This could be attributed to the high concentration of PO\({}_{4}\)-P in the PMC. However, this could \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Treatments**} & \multicolumn{4}{c}{**Model Parameters**} & \multicolumn{3}{c}{**Analysis of Variance**} \\ \cline{2-7}  & **A\({}_{\text{max}}\)** & _p_-Values & **t\({}_{\text{1/2(Amax)}}\)** & _p_-Values & **F** & _p_-Values & \(R^{2}\) \\ \hline PMC & 455.7 & \textless{}0.0001 & 16.5 & 0.0003 & 2375.7 & \textless{}0.0001 & 0.98 \\ PMCP & 441.3 & \textless{}0.0001 & 41.2 & \textless{}0.0001 & 1747.7 & \textless{}0.0001 & 0.97 \\ BCP (9:1) & 72.7 & \textless{}0.0001 & 8.2 & \textless{}0.0001 & 2044.5 & \textless{}0.0001 & 0.97 \\ BCP (8:2) & 99.3 & \textless{}0.0001 & 6.5 & \textless{}0.0001 & 2341.1 & \textless{}0.0001 & 0.98 \\ BCP (4:6) & 350.9 & \textless{}0.0001 & 42.0 & \textless{}0.0001 & 2247.0 & \textless{}0.0001 & 0.98 \\ BCP (2:8) & 455.5 & \textless{}0.0001 & 43.5 & \textless{}0.0001 & 1607.4 & \textless{}0.0001 & 0.97 \\ \hline \hline \end{tabular}  
* PMC; control as pig manure compost, PMCP; pig manure compost pellet, and BCP; ratios of biochar pellets blended of biochar/pig manure compost 2:8, 4:6, 8.2, and 9:1.  
\end{table} 
Table 2: Estimation model for accumulated NH\({}_{4}\)-N releasing from different combination rates of biochar pellets. Figure 2: Effects of NH\({}_{4}\)-N accumulated concentrations in the releasing water from biochar pellet blended with various ratios of pig manure compost during leaching periods. also result in the slower release of PO\({}_{4}\)-P in the PMCP than that found in the PMC because of the change in the physical characteristics in pelletization of pig manure compost. The curves fit was derived from the estimation model calculated by a modified equation based on correlation coefficient values (\(R^{2}\)). The estimation models for accumulated PO\({}_{4}\)-P releasing amount from different ratios of biochar pellets showed that estimation values from a modified equation were significantly correlated with the observed values for accumulated PO\({}_{4}\)-P releasing amount in all treatments (Table 3). The required time of 1/2 maximum accumulated PO\({}_{4}\)-P amount was taken 21 days in the PMCP and BCP (4:6). Similar patterns for the estimation model were observed in the accumulated NH\({}_{4}\)-N releasing models (Tables 2 and 3). The estimated releasing model has significantly fit with all the treatments (Table 3).