[Type and key drivers of nitrification for an acidic peat soil in Xiaoxing'an Mountain, China].

Acidic forest peat soil in Xiaoxing'an Mountain was used to investigate the type and key drivers of nitrification by carrying out nitrification incubation after adding 10 mL·L-1 C2H2 and different amounts of (NH4)2SO4(0, 1.2, 6.0 mmol N·kg-1). Results showed that strong mineralization (0.9-1.4 mg N·kg-1·d-1) and nitrification (0.4-0.6 mg N·kg-1·d-1) after 2 weeks of incubation were observed for both nitrogen and no nitrogen treatments, and no significant difference was observed for different (NH4)2SO4 application treatments. For C2H2 treatment, there was relatively stronger mineralization (0.8 mg N·kg-1·d-1), but no obvious nitrification (0 mg N·kg-1·d-1). These results indicated that the nitrification in acidic peat soil was mainly autotrophic, and inorganic nitrogen application did not affect nitrification rate significantly. Results also implied that the substrate (NH3) for nitrification was from the organic N mineralization, rather than the (NH4)2SO4 application. Both ammonia-oxidizing bacteria (AOB) and archaea (AOA) abundances increased significantly during 0-14 d regardless of nitrogen application. However, no significant difference in AOB and AOA abundances for different (NH4)2SO4 application treatments was observed, indicating that ammonia oxidizers did not respond positively to (NH4)2SO4 application. Compared with the treatments without C2H2, AOB and AOA abundances did not change significantly during the incubation in C2H2 treatment, suggesting that both AOA and AOB were likely the key players in nitrification in the acidic peat soil.