Abstract: This study is aimed to investigate the activities of phosphomonoesterase (acid-,neutral-,and alkaline-),phosphodiesterase and phosphotriesterase in a rice-planting meadow brown soil at the lower reach of Liao River,and their responses to different fertilization treatments.The results showed that there was no significant difference in soil total P and organic P contents among all treatments,but soil available P content was significantly higher in treatment OM than in other treatments.Soil acid-and neutral phosphomonoesterase had a higher activity than alkaline phosphomonoesterase and phosphodiesterase, while phosphotriesterase had the lowest activity.No significant difference was found in phosphatase activities between different fertilization treatments.Soil acid phosphomonoesterase activity had a significant correlation with soil total P and available P contents,while soil phosphodiesterase activity significantly correlated with soil organic P content.

Key words: Northeastern region, Forest resources, Ecological risk assessment