Synergistic regulation of ammonifying bacteria and nitrification inhibitors enhances organic fertilizer mineralization in tea plantation soils: microbial mechanisms and agronomic benefits

Aims Tea plants exhibit a strong preference for ammonium nitrogen (NH₄⁺-N), yet organic fertilizers release nitrogen slowly and are prone to nitrate leaching, createting a dual challenge of insufficient supply and loss. This study aimed to validate a synergistic strategy combining ammonifing bacteria and nitrification inhibitors to enhance organic nitrogen mineralization and NH₄⁺-N retention in tea plantion soils, and to elucidate the underlying microbial mechanisms. Methods A 56-day soil incubation experiment tested five treatments: control (CK), organic fertilizer (OF), OF with ammonifying bacteria (OM), OM + dicyandiamide (OMN1), and OM + 3,4-dimethylpyrazole phosphate (OMN2). Soil NH 4 + -N /NO 3 − -N dynamics, microbial communities, and functional genes were analyzed. Field trials further assessed the agronomic effects of four treatments (CK, OF, OMN1, OMN2) on tea yield and quality. Results The combined use of ammoniating bacteria and nitrification inhibitors synergistically enhanced NH 4 + -N availability by accelerating organic N mineralization and suppressing nitrification. This strategy reshaped microbial co-occurrence networks and enhanced the expression of nitrogen metabolism genes without altering overall diversity. enabling targeted N supply regulation. Field validation confirmed significant improvements in tea yield and quality. Conclusions Synergistic regulation of microbial nitrogen transformation offers a promising approach to optimize organic fertilization in tea plantations. By enhancing NH₄⁺-N supply and reducing nitrification loss, this strategy improves both soil nitrogen dynamics and tea production outcomes.