In order to understand the effects of increasing atmospheric nitrogen(N) deposition on the subtropical bamboo ecosystem, a nearly six-year field experiment was conducted in a Pleioblastus amarus plantation in the rainy region of SW China, near the western edge of Sichuan Basin. Four N treatment levels—control(no N added), lowN(50 kg N ha-1a-1), medium-N(150 kg N ha-1a-1),and high-N(300 kg N ha-1a-1)—were applied monthly in the P. amarus plantation starting in November 2007. In June 2012, we collected intact soil cores in the bamboo plantation and conducted a 30-day laboratory incubation experiment. The results showed that the soil N net mineralization rate was 0.96 ± 0.10 mg N kg-1day-1, under control treatment. N additions stimulated the soil N net mineralization, and the high-N treatment significantly increased the soil N net mineralization rate compared with the control. Moreover, the soil N net mineralization rate was significantly and positively correlated with the fine root biomass, the soil microbial biomass nitrogen content and the soil initial inorganic N content, respectively,whereas it was negatively correlated with the soil p H value.There were no significant relationships between the soil N net mineralization rate and the soil total nitrogen(TN)content and the soil total organic carbon content and the soil C/N ratio and the soil microbial biomass carbon content, respectively. These results suggest that N additions would improve the mineral N availability in the topsoil of the P. amarus plantation through the effects of N additions on soil chemical and physical characteristics and fine-root biomass. In order to understand the effects of increasing atmospheric nitrogen (N) deposition on the subtropical bamboo ecosystem, a nearly six-year field experiment was conducted in a Pleioblastus amarus plantation in the rainy region of SW China, near the western edge of Sichuan Basin. Four N treatment levels-control (no N added), low N (50 kg N ha-1a-1), medium N (150 kg N ha-1a-1), and high-N 1) -were applied monthly in the P. amarus plantation starting in November 2007. In June 2012, we collected intact soil cores in the bamboo plantation and conducted a 30-day laboratory incubation experiment. The results showed that the soil N net mineralization rate N additions stimulated the soil N net mineralization, and the high-N treatment significantly increased the soil N net mineralization rate compared with the control. Moreover, the soil N net mineralization rate was significantly and positively correlated with the fine root biomass, the soil microbial biomass nitrogen content and the soil initial inorganic N content, respectively, respectively, respectively, it was negatively correlated with the soil p H value. There were no significant relationships between the soil N net mineralization rate and the soil total nitrogen (TN) content and the soil total organic carbon content and the soil C / N ratio and the soil microbial biomass carbon content, respectively. respectively. These results suggest that N additions would improve the mineral N availability in the topsoil of the P. amarus plantation through the effects of N additions on soil chemical and physical characteristics and fine-root biomass.