In order to investigate the long-term effects of biochar application rate on soil available potassium and tobaccopotassium contents,two 5-year positional experiments were conducted in Bijie City,Guizhou Province.A randomized blockdesign with single factor(biochar application rate at 0,5,15,20,40 t/hm²)was used in this study.The results showedthat the increment in soil available potassium content was the highest in the first year after biochar application,which was664.21% and 223.09% in two soils,respectively,and then stabilized,with a 5-year average of 82.36% and 39.80%,respectively.Compared with the control(no biochar),5-year average increase of available potassium content was 72.2%and 127.3%,251.1% and 22.3%,31.9%,47.6% for the two soils,respectively,when the biochar application rate was15,20 and 40 t/hm².In the meantime,total potassium content in tobacco leaves increased by 18.2% and 18.4% for the twosoils,respectively.The results of these 5-year field experiments showed that the best biochar application rate was 15 t/hm² forthese two soils in order to increase the soil available potassium content and cured leaf potassium content.In conclusion,theapplication of biochar could significantly increase the soil available potassium content and cured leaf potassium content.