Abstract: In this paper， 50 top soil samples （0\|20 cm） were collected from Chinese hickory （Carya cathayensis Sarg.）orchards located at Daoshi and Tuankou towns of Linan City， Zhejiang Province， to assess the potential risk of phosphorus （P） leaching induced by long\|term fertilizer application. Soil analysis showed that soil Olsen\|P had a great spatial variability， being 0\| 893 mg·kg-1. Analysis of correlations between Olsen\|P and CaCl2\|P showed that the critical values （change\|point） of soil Olsen\|P in Daoshi and Tuankou towns were 193 and 293 mg·kg-1， respectively. Soil Olsen\|P exceeding the critical values accounted for 30% and 45% of all the investigated orchards, respectively, in Daoshi and Tuankou towns.

Key words: Chinese Hickory orchard, limestone, critical valve, P leaching, Olsen\|P, CaCl2\|P