3. Results and discussion
3.1. General properties of biochar
The ultimate analysis of biochar was performed and the chemical compositions in the studied biochar are shown in Table 1. The pH of biochar was 10.1, indicating the role of biochar in neutralizing acid soil. The P content of biochar was about 0.47% and could provide the prerequisite for reusing P in biochar. Besides phosphate, the biochar contains various functional groups, such as Cdouble bond; length as m-dashO, Csingle bondOsingle bondC, Cdouble bond; length as m-dashC, single bondOH, and Sisingle bondOsingle bondSi. based on the FTIR spectra (Fig. S1 in Supplementary material (SM)). The pHpzc of biochar is 8.0–8.5 according to the method described in S1.