Net N mineralization and nitrification rate
N mineralization rate in soil was significantly higher in R30 and R90
than in other treatments (Fig. 4). Net nitrification rate increased
along the N input gradient after the N addition cessation (Fig. 4).
Compared to R0, net nitrification rates increased by 20%, 39%, and
64% in R60, R90, and R120 treatments, respectively (Fig. 4). Pearson
correlation analysis showed that N mineralization rates significantly
positive correlated with AOB abundance (r= -0.45, p < 0.05)
and microbial biomass N (r= -0.47, p < 0.05). Similarly,
increased net nitrification rate was significantly related to AOB
abundance (r= -0.57, p < 0.05) and microbial biomass N (r=
-0.73, p < 0.001) (Fig. S2).