Effect of soil water content on water-soluble aluminum concentration in relation to the occurrence of common scab of potato in two Andosol types

抄録

To analyze the effect of irrigation on the occurrence of common scab of potato, we examined the relationship between the water content and water-soluble aluminum concentration under low soil water content conditions in two types of Andosols. The content of water-soluble aluminum per dry soil in the Haplic Andosol, conducive to this disease at a soil of pH of around 5.2, was low, ranging from 0.043 mg kg^<-1> to 0.070 mg kg^<-1>, regardless of the soil water content. On the other hand, the content of water-soluble aluminum per dry soil in the Umbric Andosol, suppressive for this disease at a soil pH of around 5.2, was 0.298 mg kg^<-1> under 30% soil water conditions, and the concentration of water-soluble aluminum in the soil solution increased with the increase in the water content. These results indicated that the water-soluble aluminum concentrations under the field conditions were different between the two Andosol types. Moreover, this study suggested that the effect of irrigation on the control of common scab of potato in the Haplic Andosol did not involve a synergy between the water-soluble aluminum concentration and soil water content. On the other hand, the soil water content was one of the control factors for the occurrence of common scab of potato in the Umbric Andosol, as indicated by the increase in the water-soluble aluminum concentration in the soil solution along with the increase in the soil water content.