This study was conducted to select proper soil amendments in order to reduce the occurrence of potato scab and maintaining soil health by applications of dolomitic lime, sulfur, potassium sulfate, shell meal fertilizer, silicate fertilizer, lime nitrogen and ammonium sulfate fertilizer in different pH levels of volcanic ash soil with continuous cultivation of potato. In potassium sulfate-applied plot with a low soil pH, the incidence rate and disease severity of scab were lowest at 84.4% and 28.4%, respectively. Those were lowest among the treatments. Value of potato scab control was 12.3% and marketable yield of potato was highest at 93.2%. In lime nitrogen-applied plot (60 kg/10a), the incidence rate was low at 38.3%, and control value was 23.8% and marketable yield of potato was high at 66.3%. In relatively higher pH soils, the incidence rate of scab was lowest at 38.3% in the lime nitrogen-applied plot (60 kg/10a). Value of potato scab control was 23.8%, which was four times higher than that in sulfur-applied plot. Marketable yield of potato was highest at 66.3% in the lime nitrogen-applied plot. In the lime nitrogen plot infected with potato scab pathogen such as S. acidiscabies and S. scabiei were remarkably lower than other soil amendments at 2.5, 5, and 10 g/L concentrations of lime nitrogen using Glucose Yeast Malt (GYM) medium. In conclusion, this study suggests that potassium sulfate application in low pH soil (less than pH 5) and lime nitrogen application in relatively higher pH soil (more than pH 6) before potato seeding might be helpful to reduce the occurrence of potato scab.