Abstract
Strongly bleached red and yellow soils which are termed feichisha are distributed on the plateaus and hilly regions in the middle and northern part of Okinawa Island. They have diagnostic profiles which are composed of a coarse-grained gray surface horizon and a reddish or yellowish-brown subhorizon with rather high clay content. They are considered to have been formed under the influence of podzolization, surface pseudogleyzation, lessivage, and so on, but their participation in the forming process of those horizons have not been clearly confirmed. We have studied physically, chemically, mineralogically and micromorphologically the strongly bleached red and yellow soils which are located at the edge of gentle slope and on the midslope on Minami-Meiji Yama of Okinawa Island. The results obtained are as follows: 1) Lessivage is just at the beginning in these soils, and the clear differences in clay content between the surface horizons and subhorizons, are mainly derived from sedimentary origin. 2) The forming process of the gray surface horizon is surface pseudogleyzation strongly influenced by organic matter. 3) Eluviated substances by the process are leached out with the lateral movement of soil water.
