ACTIVE ALUMINUM STATUS IN SURFACE HORIZONS SHOWING CONTINUOUS CLIMOSEQUENCE OF VOLCANIC ASH-DERIVED SOILS IN TOWADA DISTRICT, NORTHEASTERN JAPAN

The relationship between the status of active Al of surface horizons f ormed in Towada-a ash and climatic conditions was studied in the Towad a district, Aomori Prefecture, The mean monthly air temperature and pr ecipitation were estimated from 1-km(2) mesh data supplied by the Japa n Meteorological Agency, Thornthwaite's P-E (precipitation-evapotransp iration) index was used as the single climatic index combining the tem perature and precipitation, The results showed that the status of acti ve Al was definitely dependent on the P-E index, representing a contin uous Spodosol-nonallophanic Andisol-allophanic Andisol transition.