Persistent soil acidification contrasts with context-dependent enzyme and microbial responses after two decades of nitrogen addition in two subtropical forest types

This dataset contains raw data from a long-term (two-decade) nitrogen (N) addition experiment conducted in mixed pine–broadleaf forests at Dinghushan, southern China. The study examined the effects of chronic N deposition on belowground biological responses across seasons and soil depths. The experiment includes three N addition levels: control (C, 0 kg N ha⁻¹ yr⁻¹), low nitrogen (L, 50 kg N ha⁻¹ yr⁻¹), and medium nitrogen (M, 100 kg N ha⁻¹ yr⁻¹). Soil samples were collected from six plots in two soil layers (0–10 cm and 10–20 cm) during both dry and rainy seasons, yielding 72 samples in total. The dataset comprises: Soil physicochemical properties: soil moisture (%), pH (H₂O), NO₃⁻–N (mg/kg), NH₄⁺–N (mg/kg), total nitrogen (TN, %), total carbon (TC, %), total phosphorus (TP, %), and C:N ratio. Extracellular enzyme activities: acid phosphatase (AP), β-glucosidase (BG), β-xylosidase (BX), cellobiohydrolase (CBH), β-galactosidase (GAL), and N-acetyl-β-glucosaminidase (NAG). Microbial community composition (PLFA biomarkers): fungi, Actinobacteria, Gram-positive bacteria (G+), Gram-negative bacteria (G−), arbuscular mycorrhizal fungi (AMF), total bacteria, and the ratios G+:G− and fungi:bacteria (F:B).