A large number of shortterm laboratory and field trails show that biochar amendment can increase soil carbon sequestration,improve soil fertility and crop yields.However,little is known about its longterm effect on soil fertility.Therefore,the aim of this study was to assess the longterm effect of biochar amendments on soil fertility based on a 10year field experiment.Four treatments were set up:control(CK),biochar 4.5 t·hm-2·yr-1 (B4.5),biochar 9.0 t·hm-2·yr-1(B9.0)and straw retention(SR).Results showed that biochar treatments and straw retention did not significantly affect soil pH,but decreased soil bulk density by 2.2%~8.2%,soil conductivity was decreased sharply by 1.5%~7.8% with increasing application rates in biochar treatments,and was increased by 4.7%~13.4% in straw retention,respectively compared to control.Soil organic matter and total nitrogen contents were enhanced by 57.7%~123.1% and by 11.3%~21.9%,respectively,and total phosphorus content did not significantly change under the biochar and straw treatments.Soil ammonium(NH+4-N)content did not show significant difference between the treatments,but nitrate(NO-3-N)content was increased by 3.8%~67.1% under the biochar and straw treatments and this difference was statistically significant under the higher biochar application rate.The biochar and straw treatments significantly reduced soil available phosphorus content by 23.1%~42.0%,but increased available potassium content by 2.0%~23.1%.In general,the longterm biochar application enhanced soil fertility,especially significantly increased soil organic matter.