## 3 Results and Discussion
### Soil Inorganic Phosphorus Speciation
However, some heavily fertilized acid soils might have significant amounts of Ca-P [52] because hydroxyapatite is considered a product of the super-phosphates dissolution in acidic and slightly acidic soils [53]. Where there is soil-maize plant interaction (49 DAS), the use of CZ and RP in acid soils enhances P release via an exchange-induced dissolution system, and the process is mediated by plants [11; 12]. Moreover, uptake of cations from CZ liberates exchange sites which are occupied by Ca\({}^{2+}\), thus lowering Ca\({}^{2+}\) concentration in soil solution. This process might have induced further dissolution of RP to maintain P equilibrium. The dissolution of RP might have also been facilitated by a generation of H\({}^{+}\) through nitrification and root efflux. Plant roots also promote dissolution of RP through excretion of protons or through uptake of phosphate [54]. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & & \multicolumn{2}{c}{**TSP**} & \multicolumn{4}{c}{**ERP**} & \multicolumn{2}{c}{**CIRP**} \\ \cline{2-10}
**Pi Fraction** & **T0** & **T1** & **T2** & **T0** & **E1** & **E2** & **T0** & **C1** & **C2** \\ \hline Sol-P & 0.23c & 3.46a & 1.71b & 0.23b\({}^{\prime}\) & 0.96a\({}^{\prime}\) & 0.86a\({}^{\prime}\) & 0.23c\({}^{\prime\prime}\) & 0.69b\({}^{\prime\prime}\) & 0.98a\({}^{\prime\prime}\) \\ (ppm) & \(\pm\)0.02 & \(\pm\)0.33 & \(\pm\)0.11 & \(\pm\)0.02 & \(\pm\)0.11 & \(\pm\)0.08 & \(\pm\)0.02 & \(\pm\)0.02 & \(\pm\)0.11 \\ Al-P & 6.42b & 66.43a & 62.10a & 6.42c\({}^{\prime}\) & 24.54a\({}^{\prime}\) & 19.14b\({}^{\prime}\) & 6.42c\({}^{\prime\prime}\) & 18.65a\({}^{\prime\prime}\) & 15.42b\({}^{\prime\prime}\) \\ (ppm) & \(\pm\)0.58 & \(\pm\)6.76 & \(\pm\)2.51 & \(\pm\)0.58 & \(\pm\)1.40 & \(\pm\)1.73 & \(\pm\)0.58 & \(\pm\)0.65 & \(\pm\)0.60 \\ Fe-P & 33.42a & 47.27a & 47.27a & 33.42b\({}^{\prime}\) & 54.14a\({}^{\prime}\) & 54.68a\({}^{\prime}\) & 33.42b\({}^{\prime\prime}\) & 219.87a\({}^{\prime\prime}\) & 204.40a\({}^{\prime\prime}\) \\ (ppm) & \(\pm\)1.49 & \(\pm\)5.37 & \(\pm\)4.43 & \(\pm\)1.49 & \(\pm\)0.91 & \(\pm\)1.85 & \(\pm\)1.49 & \(\pm\)6.37 & \(\pm\)11.78 \\ Ca-P & 3.15a & 4.16a & 3.35a & 3.15b\({}^{\prime}\) & 4.37 ab\({}^{\prime}\) & 4.91a\({}^{\prime}\) & 3.15b\({}^{\prime}\) & 6.22a\({}^{\prime}\) & 7.39a\({}^{\prime\prime}\) \\ (ppm) & \(\pm\)0.12 & \(\pm\)0.46 & \(\pm\)0.25 & \(\pm\)0.12 & \(\pm\)0.55 & \(\pm\)0.36 & \(\pm\)0.12 & \(\pm\)0.33 & \(\pm\)0.66 \\ Red-P & 5.60c & 27.67a & 16.90b & 5.60b\({}^{\prime}\) & 124.27a\({}^{\prime}\) & 146.85a\({}^{\prime}\) & 5.60c\({}^{\prime\prime}\) & 24.45b\({}^{\prime\prime}\) & 89.35a\({}^{\prime}\) \\ (ppm) & \(\pm\)0.32 & \(\pm\)3.87 & \(\pm\)1.13 & \(\pm\)0.32 & \(\pm\)9.12 & \(\pm\)12.41 & \(\pm\)0.32 & \(\pm\)2.57 & \(\pm\)9.35 \\ Cocl-P & 5.43b & 8.48a & 7.80a & 5.43b\({}^{\prime}\) & 18.31a\({}^{\prime}\) & 18.02a\({}^{\prime}\) & 5.43b\({}^{\prime\prime}\) & 59.60a\({}^{\prime\prime}\) & 56.26a\({}^{\prime\prime}\) \\ (ppm) & \(\pm\)0.09 & \(\pm\)0.82 & \(\pm\)0.91 & \(\pm\)0.09 & \(\pm\)1.21 & \(\pm\)0.53 & \(\pm\)0.09 & \(\pm\)4.55 & \(\pm\)0.81 \\ \hline \hline \end{tabular} Means within row with different letters indicate significant difference using [PERSON]’s test at \(p\leq 0.05\). The ‘\(\pm\)’ indicates standard error of quadruplicates. Pi is inorganic phosphorus,Sol-P is loosely soluble P. Al-P is aluminum bound P. Fe–P is iron bound P, Ca–P is calcium bound P, Red-P is reductant P, and Oocl-P is occluded P.  
\end{table} 
Table 7: Inorganic phosphorus speciation of soil at forty-nine days after seeding. Plant Dry Matter Production, Phosphorus Concentration, Phosphorus Uptake, and Phosphorus Use Efficiency  
The total plant dry matter production, P content in the maize plants, P uptake, and P use efficiency results are shown in Table 8. The poor dry matter production in T0 was as predicted because infertile soils are unable to sustain the growth and development of maize plants.