highly significantp < 0.001
All alpha diversity indices differed markedly among soil depths, with highly significant effects observed for depth ( p < 0.001).
All alpha diversity indices differed markedly among soil depths, with highly significant effects observed for depth ( p < 0.001).
Across all fertilization treatments, nitrification- and denitrification-related genes exhibited an increasing trend with soil depth, with the highest abundances consistently observed in the deep soil layer (40–60 cm).