## 2 Materials and Methods
### Crop Recovery and Agronomic Efficiency of Triple Superphosphate Applied in Pot Trial  
Crop recovery (RE\({}_{\text{P}}\)) and aAgronomic efficiency (AE\({}_{\text{P}}\)) results (Table 10) suggest P was higher in the soils with CLB than in the soil with the standard practice (T2) (Table 10). This confirms the findings of [PERSON] et al. that biochars could enhance P availability and uptake [45]. [PERSON] et al. raised the concerns for a sustainable P fertilizer used because of the continued depletion of P fertilizer reserves in the world [46]. In this regard, biochar produced from animal wastes could be an alternative P source. Results of this present study further confirm that the use of CLB does not only serve as a source of P, but it can also increase efficient utilization of P fertilizers. Crop recovery of applied TSP increased with increasing rate of TSP and CLB (Table 10). This finding also suggests that biochar from manures contains highly soluble P which directly increases soil available P [47]. Furthermore, CLB improves soil micro-environment for phosphatase activities such as transforming organic P into inorganic P thereby making it available for plant uptake [48]. Results on agronomic efficiency is consistent with the increase in the maize plant dry matter yield of the treatments with CLB (Table 10). The agronomic efficiency of T10, T11, and T12 were highest and this supports the increase in plant dry matter yield of T10 as discussed earlier. Effects of Different Amounts of Chicken Litter Biochar and Phosphorus on Soil Physico-Chemical Properties at Fifty Days after Sowing  
Soil total organic carbon of T2 was not statistically different from that of T1 but lower than the soils with CLB. Among the soils with CLB, T3 showed statistically higher effect on total organic carbon than those of T4, T5, T6, T7, T8, T9, T10, T11, and T12 (Figure 6). Increase in the total organic carbon of the soils with the CLB suggests the contribution of this organic amendment to soil organic matter. Among the treatments, T3 showed the highest effect because it had 100% CLB. This also suggests that soil total organic carbon increases with increasing amount of CLB. [PERSON] et al. attributed the increase in maize yield to increase soil organic carbon following application of biochar [48]. Biochar use on acid soils also improved soil total organic carbon [49; 50]. Biochar's are stable in soils such that they are able to store soil carbon for many years [51; 52]. Moreover, they provide soil nutrients in addition to improving soil water holding capacity. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**TSP**} & **Total P** & **Dry Matter** & **Crop Recovery** & **Agronomic** & **\% Increase** \\  & **Uptake** & **Yield** & **Efficiency of** & **Applied P** & **Applied P** & **in Yield** \\ \hline \hline \multicolumn{6}{c}{**g pot\({}^{-1}\)**} \\ \hline T1 & 0.00 & 0.01 & 6.89 & 0 & 0.00 & 0.00 \\ T2 & 4.80 & 0.15 & 47.91 & 0.03 & 8.55 & 85.62 \\ T3 & 0.00  
Soil pH in water and KCl of T1 and T2 were statistically lower than those of T3, T4, T5, T7, T8, T9, T10, T11, and T12. Among the soils with CLB, pH of T3 was statistically higher than those of T4, T5, T7, T8, T9, T10, T11, and T12 (Figures 7 and 8) because biochars have some alkaline materials [52; 53] and because of this, they are able reduce soil acidity [54; 55]. This also explains the liming effect of biochars [56]. Their liming effect had been associated with alkaline metals (Ca, Mg, and K) oxides [57; 58; 59]. Generally, biochar application to nutrient-imporerished tropical soils considerably improves soil fertility by not only increasing soil pH but it also reduces Al and Fe hydrolysis or Al and Fe toxicity. These positive effects of biochars improve soil quality/health and crop yields [60]. Soil total and available P of T2 were not statistically different from those of T5, T6, T8, T9, and T12 but lower than those of T3, T4, T7, and T10 (Figures 9 and 10).