『Abstract
　To date, numerous studies have employed single type nitrogen (N) addition methods in reporting influences of N deposition on soil extracellular enzymatic activities (EEA) during litter decomposition in forest ecosystems. As natural atmospheric N deposition is a set of complex compounds including inorganic N and organic N, it is essential for investigating responses of soil EEA to various mixed N fertilization. In a subtropical forest stand in Zijin Mountain, East China, various N fertilizers with different inorganic N and organic N ratios were added to soils monthly from 2008 to 2009. Samples were harvested from N fertilized and control plots every 4 months. Subsequently, six EEA were assayed. A laboratory experiment was also conducted simultaneously. Both field and laboratory experiments showed that various mixed N fertilizations revealed different influences on soil EEA. Acceleration of most soil EEA by mixed N fertilization was greater than that of single N fertilization. The majority of soil extracellular enzymes exhibited the highest activities under mixed N fertilization, with the ratio of inorganic N to organic N at 3:7. These results suggested that N type and ratio of inorganic N and organic N were important factors controlling soil EEA, and the 3:7 ratio of inorganic N and organic N may be the optimum for soil EEA.

Keywords: Extracellular enzyme activity; Forest soil; Inorganic nitrogen; Nitrogen deposition; Organic nitrogen』

1. Introduction
2. Methods
　2.1. Site description
　2.2. Field experiment
　2.3. Laboratory experiment
　2.4. Chemical analysis and enzymatic assays
　2.5. Statistical analyses
3. Results
　3.1. Changes in soil EEA of the field experiment
　3.2. Changes in soil EEA of the laboratory experiment
　3.3. Changes in soil EEA and pH values within NaHCO3 addition
4. Discussion
5. Conclusion
Acknowledgements
References