Objective The aims were to investigate the effects of Pteroceltis tatarinowii biochar on soil nutrients and enzyme activities in farmland affected by copper tailings, and to ensure the suitable application amounts of this biochar.

Method Unmodified P. tatarinowii biochar (BC) and manganese-modified P. tatarinowii biochar (MBC) were used as exogenous additives to analyze the changes in basic soil nutrients and common enzyme activities.

Result The addition of both BC and MBC had significant effects on soil nutrient contents and enzyme activities (P < 0.05). MBC exhibited more pronounced effects than unmodified BC, and the effects increased with higher application rates. Specifically, it promoted increases in soil organic matter, available phosphorus, catalase activity, and urease activity, while it inhibited soil available nitrogen and sucrase activity. Compared to the group without biochar addition, the 5% BC treatment group increased soil organic matter content by 45.2%, reaching a maximum of 25.52 g kg⁻¹; catalase activity was 1.04 times that of the no-biochar group, and the urease activity increased by 49.4%. However, soil available nitrogen content decreased by 10.4%, and soil sucrase activity decreased by 40.6% compared to the no-biochar group.

Conclusion Both unmodified and manganese-modified P. tatarinowii biochar effectively improved soil nutrients and enzyme activities in the farmland soil of the copper tailings area. The exogenous application of 3% - 5% manganese-modified P. tatarinowii biochar showed the most significant effects.