Purpose <p>To identify the optimal ratio for enhancing soil phosphorus availability, this study examined the effects of biochar and wood vinegar, applied individually and in combination at various ratios, on the phosphorus adsorption characteristics of soil.</p> Materials and methods <p>Biochar was incorporated into soil samples at mass ratios of 0%, 1%, 3%, and 5%. Each mixture was then divided into two portions, with wood vinegar evenly sprayed onto one portion. The effects on phosphorus adsorption were analyzed alongside changes in soil properties, including pH, electrical conductivity (EC), soil organic carbon (SOC), cation exchange capacity (CEC), and alkaline phosphatase (ALP) activity.</p> Results and discussion <p>Results demonstrated that biochar amendment reduced soil phosphorus adsorption by 2.93–26.65%, with the combined application of wood vinegar further decreasing adsorption by 4.43–28.02%, likely due to competitive adsorption of organic acid anions. The largest reduction in phosphorus adsorption was observed with the combination of wood vinegar and a medium dose of biochar (3% mass ratio). Negative correlations were observed between soil pH, EC, and SOC with the phosphorus adsorption coefficient <i>K</i>_<i>l</i>, while positive correlations were observed for CEC and ALP. The environmental factors influencing phosphorus adsorption were ranked in the order of EC &gt; SOC &gt; CEC &gt; ALP &gt; pH.</p> Conclusions <p>Combining 3% biochar with wood vinegar could effectively enhance soil phosphorus availability by reducing phosphorus adsorption, influenced by changes in environmental factors.&#xa0;</p>