Abstract: From November 2007 to May 2009, a simulation test was conducted in a Pleioblastus amarus plantation in Rainy Area of West China to study the effects of nitrogen deposition on the activities of soil enzymes. Four treatments were installed, i.e., control (0 g N·m^-2·a^-1), low nitrogen (5 g N·m^-2·a^-1), medium nitrogen (15 g N·m^-2·a^-1), and high nitrogen (30 g N·m^-2·a^-1). Half year after N deposition, 0-20 cm soil samples were collected monthly, and the activities of peroxidase, polyphenol oxidase, cellulase, sucrase, urease, and acid phosphatase were determined. All test enzyme activities had apparent seasonal variation, with the peak of cellulase, sucrase, and acid phosphatase activities in spring, of urease activity in autumn, and of peroxidase and polyphenol oxidase activities in winter. Nitrogen deposition stimulated the activities of polyphenol oxidase, sucrase, urease, and acid phosphatase, inhibited cellulase activity, but had no significant effects on peroxidase activity. The test P. amurus plantation ecosystem was N-limited, and nitrogen deposition stimulated the decomposition of soil organic matter by microbe-enzyme system.

Key words: nitrogen deposition, soil enzyme activity, Pleioblastus amarus plantation, Rainy Area of West China, wheat and faba bean intercropping, root exudates, amounts of organic acids, types of organic acids, exudation rate.