<p>Excessive use of phosphorus (P) in farmland soil and improper disposal of crop residues such as straws accelerate the consumption of P resources and cause a high level of air and water pollution, which are the main limiting factors for sustainable agricultural development. The most important alternative is the introduction of organic fertilizers to replace mineral P fertilizer. However, the type of organic fertilizers and management methods differ significantly. In this study, we used solution 31-P nuclear magnetic resonance spectra and Hedley fractionation method to characterize the P compounds in the initial soil (in 2013; CK0), long-term unfertilized (CK) soil, and the soils treated with N+P+K mineral fertilizer (NPK), biochar in combination with NPK fertilizer (CNPK), and corn straw in combination with NPK fertilizer (SNPK). The results showed that adding biochar significantly increased the concentration of P. However, Olsen-P was found to be the highest (21.88 mg kg<sup>−1</sup>) in SNPK. The concentration of Hedley-P was the highest (574.76 mg kg<sup>−1</sup>) in CNPK. The inorganic P forms were significantly increased by adding biochar (up to 183.9 %). The concentration of orthophosphate is positively relative to Resin-P, NaHCO<sub>3</sub>-inorganic P (Pi; organic P (Po)), NaOH-Po, and Residual-P, which are absorbed and utilized to plants and microorganisms. Adenosine monophosphate (AMP) and inositol hexakisphosphate (IHP) are potential sources of P. Compared to the direct application of straw, adding biochar increases the available P in the different soil and reduces environmental pollution.</p>