We investigated that influences of Al/Si and contents of non-crystalline materials and meteological factors on the accumulation of humus in Andisols using multiple regression analysis. The total carbon contents as the quantities of he humus accumulation had a correlation with the acid oxalate extractable Si as the contents of non-crystalline materials. Further, the total carbon contents had a correlation with the Al/Si of non-crystalline materials. However, each correlation was impossible to explain accumulations of humus completely. Therefore, it was tried to use a multiple regression analysis. The result of the multiple regression analysis indicated that the humus accumulation was influenced by the contents and Al/Si of non-crystalline materials. It was considered that an active Al which was contained in the non-crystalline material promoted humus accumulation because the active Al induced humification. The quantities of the humus accumulation had a correlation with the temperature. We consider that high temperature caused plants growth, therefore many organic matter were supplied in soils.
