Tobacco biochar-loaded with soluble fertilizer enhances the yield and quality of Nicotiana tabacum: an in-situ field study

A novel soil amendment, TBLSF, was developed by combining tobacco waste-derived biochar (TB) with a soluble fertilizer (SF). Its synergistic effects on tobacco yield, leaf quality, and soil health were evaluated through in-situ field experiments. Application of TBLSF significantly enhanced tobacco growth, increasing plant height by 13.35–15.51%, maximum leaf area by 28.22%, and shoot fresh weight by 1.71-fold. Simultaneously, TBLSF improved leaf chemical quality by increasing potassium (K+) and phosphorus (P) concentrations in upper leaves by 36.8% and 38.6%, respectively, elevating the K+/Cl– ratio by 36.2%, and enhancing soluble sugar content by 47.2%. Regarding soil health, TBLSF increased rhizosphere soil cation exchange capacity (CEC) by 28.80% and available phosphorus by 89.49%, accompanied by significant increases in urease and acid phosphatase activities. Microbial community analysis further revealed that TBLSF enriched beneficial bacterial populations while suppressing pathogenic fungi. In conclusion, TBLSF acts as a dual-functional amendment that enhances both tobacco productivity and quality while improving soil physicochemical and microbial properties, demonstrating its strong potential for sustainable tobacco cultivation.