The minerals in biochars were analyzed by X-ray Powder Diffraction (XRD). The tests were performed on a Rigaku, Ultima IV Diffractmeter (Rigaku Corporation, Japan), and Cu Kα radiation generated at 40 kV/40 mA, data were collected in the range (2θ) from 0° to 60° with the scan step of 0.02°. The minerals in the samples were identified using the XRD data analysis software (MDI JADE 6.5) and its corresponding powder diffraction file (PDF) database. The Zn species on biochars were analyzed by the method of extended X-ray Absorption Fine Structure (EXAFS) spectroscopy in fluorescence modes. Zn K-edge (9659 eV) measurements were carried out at beamline BL14W at the Shanghai Synchrotron Radiation Facility Center (SSRF). Principal Component Analysis (PCA) accompanied with Linear Combination Fitting (LCF) were used for species identification and quantification. The details of EXAFS spectra collection and data processing were shown in Supplementary S11.