Abstract: Phosphorus is one of the limiting factors for plant growth. Though organic phosphorus is dominant in soil, it can only be used after mineralization and hydrolysis by phosphatase. Therefore, study on soil phosphatase activities would provide a method to activate phosphorus in soil, which is not labile. By using alfalfa and chestnut soil in our pot experiment, soil phosphatase activities were studied under different phosphorus and water treatments. The results showed that alkaline phosphomonoesterase activities (99.2-170.0 mg paranitrophenol·kg^-1 soil·h^-1) were higher than acid phosphomonoesterase activities (24.7-56.9 mg paranitrophenol·kg^-1 soil·h^-1); soil acid phosphomonoesterase and phosphodiesterase activities were significantly affected by waterfertilizer interaction, and higher phosphorus content inhibited soil inorganic pyrophosphatase activities under routine water treatment. Severe drought reduced soil acid phosphomonoesterase, phosphodiesterase and inorganic pyrophosphatase activities, while phosphorus fertilizer increased soil acid and alkaline phosphomonoesterase activities. Therefore, soil water and phosphorus control might inhibit or activate soil phosphatase activities.

Key words: central Sichuan hilly area, land use type, soil physical and chemical property, grey correlation analysis., analy-tic hierarchy process