Aims Soil in tea plantations is characterised by severe acidification and high aluminium and fluorine content. Applying excessive nitrogen (N) is a common strategy in tea plantations. Fungal and bacterial responses to N fertiliser addition in tea plantations, especially their relationship with tea growth, quality, and soil microbiome composition, remain unclear. Methods We performed a field experiment using different N fertiliser application rates for 5 years (2016‒2020) in a tea-producing region of China. Results Application of excessive N (600 kg ha− 1 y− 1) reduced tea yield and quality. High N application rates (360 and 600 kg ha− 1 y− 1) significantly decreased bacterial and fungal diversity and altered the compositions of bacterial and fungal communities (P