## 4 Conclusions  
Amending a tropical acid soil with CLB can reduce total acidity, exchangeable Al\({}^{3+}\), and exchangeable H\({}^{+}\) and it also increases soil pH. The reduction of soil acidic cations (Al\({}^{3+}\), Fe\({}^{3+}\), and H\({}^{+}\)) does not only increase soil pH but it also mitigates P fixation by Al\({}^{3+}\) and Fe\({}^{3+}\). Soil total P, \begin{table}
\begin{tabular}{c c c c c c} \hline  & **Total N** & **Exchangeable K** & **Exchangeable Ca** & **Exchangeable Mg** & **Exchangeable Na** \\ \cline{2-6}  & \% & & **cmol kg\({}^{-1}\) & \\ \hline T1 & 4.72a \(\pm\) 0.02 & 0.81e \(\pm\) 0.05 & 0.5f \(\pm\) 0.01 & 0.1g \(\pm\) 0.004 & 0.0046g \(\pm\) 0.0001 \\ T2 & 4.61a \(\pm\) 0.03 & 1.33e \(\pm\) 0.04 & 0.51e \(\pm\) 0.01 & 0.11g \(\pm\) 0.007 & 0.0049g \(\pm\) 0.0001 \\ T3 & 5.51a \(\pm\) 0.09 & 2.90 ab \(\pm\) 0.08 & 1.46a \(\pm\) 0.07 & 0.39a \(\pm\) 0.01 & 0.0024a \(\pm\) 0.0002 \\ T4 & 5.245a \(\pm\) 0.03 & 2.43d \(\pm\) 0.06 & 1.23 ab \(\pm\) 0.02 & 0.356 bc \(\pm\) 0.003 & 0.0011 ab \(\pm\) 0.0001 \\ T5 & 5.01a \(\pm\) 0.02 & 1.87 de \(\pm\) 0.03 & 0.95 cd \(\pm\) 0.03 & 0.29e \(\pm\) 0.008 & 0.0042 cd \(\pm\) 0.0003 \\ T6 & 4.86a \(\pm\) 0.02 & 1.28e \(\pm\) 0.05 & 0.76r \(\pm\) 0.02 & 0.1f \(\pm\) 0.006 & 0.0051f \(\pm\) 0.0003 \\ T7 & 5.20a \(\pm\) 0.02 & 2.38 ab \(\pm\) 0.2 & 1.14 abc \(\pm\) 0.06 & 0.32 bed \(\pm\) 0.007 & 0.002 bc \(\pm\) 0.0001 \\ T8 & 5.17a \(\pm\) 0.02 & 2.24 ab \(\pm\) 0.12 & 1.04 bc \(\pm\) 0.05 & 0.25 de \(\pm\) 0.013 & 0.0055 de \(\pm\) 0.0003 \\ T9 & 4.99a \(\pm\) 0.08 & 1.65 bc \(\pm\) 0.16 & 0.74 de \(\pm\) 0.04 & 0.2f \(\pm\) 0.008 & 0.003 ef \(\pm\) 0.0003 \\ T10 & 5.22a \(\pm\) 0.02 & 2.51a \(\pm\) 0.06 & 1.28 ab \(\pm\) 0.03 & 0.37b \(\pm\) 0.014 & 0.0026 ab \(\pm\) 0.0002 \\ T11 & 5.06a \(\pm\) 0.02 & 2.36 abc \(\pm\) 0.1 & 1.06 bc \(\pm\) 0.02 & 0.32 cde \(\pm\) 0.009 & 0.0028 bc \(\pm\) 0.0004 \\ T12 & 4.95a \(\pm\) 0.06 & 1.69 bc \(\pm\) 0.09 & 0.77 de \(\pm\) 0.03 & 0.22f \(\pm\) 0.015 & 0.0015e \(\pm\) 0.0001 \\ \hline \end{tabular} Note: Different letters within a column indicate significant difference between means of three replicates \(\pm\) standard error using [PERSON]’s test at \(p\leq 0\).  
\end{table} 
Table 11: Chick letter biochar and triple superphosphate on soil exchangeable cations after pot study. Figure 16: Effects of treatments on soil cation exchange capacity. Different letters indicate significant difference between means using [PERSON]’s HSD (Honestly Significant Difference) test at \(p\leq 0.05\). The error bars are the \(\pm\) standard error of triplicates. Figure 15: Effects of treatments on soil exchangeable Fe\({}^{2+}\). Different letters indicate significant difference between means using [PERSON]’s HSD (Honestly Significant Difference) test at \(p\leq 0.05\). The error bars are the \(\pm\) standard error of triplicates. available P, and water-soluble P were increased with increasing rate of CLB because of the P content in this organic amendment. Additionally, the effect of different rates of the CLB on efficiency of TSP indicated that, using 25% and 50% CLB of 5 t ha\({}^{-1}\) with 75% TSP significantly increased soil P availability, recovery, agronomic use efficiency, and dry matter yield of maize plant compared with the chemical fertilization alone. The CLB can also increase not only soil total organic carbon but it can also increase availability of base cations exchangeable K, Ca, Mg, and Na. to enhance growth and development of maize plants. Although 75% chicken litter biochar of 5 t ha\({}^{-1}\) with 75% TSP significantly increased soil P availability, recovery, agronomic use efficiency, and dry matter yield of maize plant, economically, using 25% and 50% chicken litter biochar of 5 t ha\({}^{-1}\) with 75% TSP will be more profitable. The findings of this study suggest that application of CLB alone does not improve maize growth and development because of insufficient P in CLB to support the growth of maize plant.