Comparative study on Andosols developed under grassland and forest was carried out in regions with different lithological regime in Japan to discuss the influence of vegetation management to soil chemical properties. The following are the results of soil investigation and soil analysis on the four studied regions, which are Tamayama of northern Japan, Bodai of central Japan, Sanbe of western Japan, and Aso of southern Japan. Andosols properties have shown significant difference between grassland pedon and forest pedon. Continuous grassland use characterized Andosols with thick humic horizon, relatively, high humification degree, high base saturation degree, and low soil acidity. These characteristics are to be estimated as response of vegetation management, or human impact, such as burning or grazing, which effect to accelerate the circulation of bases. Soil humus properties of the surface soil of both grassland and forest pedon have shown regionality. In Tamayama, Bodai, and Aso region, a the significant difference in humification degree was represented by RF value and Δ logK, between grassland and forest pedon. In comparision, as for Sanbe region, the humification degree remained high even in the secondary forest soil. The difference of soil acidity between two types of vegetation control, grassland and forest, has shown geographical differentiation related to the diverse conditions of parent materials. Soils composed of layered silicate clay, especially remarked in Sanbe and Tamayama pedon, have wide ranged difference between grassland and forest. The existence of layered silicate clay in the Andosols, act to amplify the difference of soil acidity according to the strength of vegetation control.
