Clay mineralogical properties of brown forest soils in northern Kyoto with special reference to their pedogenetic process

Characteristics of brown forest soils in Northern Kyoto as compared with andisols, red- and/or yellow-colored soils, and podzolic soils

“…This observation is consistent with the clay mineralogical changes in the profile characterized by the fact that 2 : 1 : 1-2 : 1 intergrades in the subsurface horizon give way to smectite in the surface via vermiculite (Hirai et al 1989).…”

“…This difference in the A1 horizon between the Ando soils and the brown forest soils may be attributed to the different nature of organic matter and to the associated low Alo content. Since the A 1 horizon of the brown forest soils gives a very acid reaction, with a pH value below 4:0, such a strong acidity leads to the dissolution of AI oxides and interlayered compounds in 2 : 1-2 : 1 : 1 intergrade clay minerals (Hirai et al 1989). As a result, A1 is translocated, leading to a relatively low Alo content in the A1 horizon.…”

“…The distribution pattern of Alo, Alp, and Ald (Hirai et al 1988) and the clay mineralogical changes in the profiles of the brown forest soils as compared with the podzolic soils (Hirai et al 1989) suggested that podzolization took place in the brown forest soils. On the contrary, the significant difference observed in the redistribution coefficient of Feo and Fed (Hirai et al 1988) indicates that the intensity of podzolization was greater for the podzolic soils than for the brown forest soils.…”

“…c) In no horizons did the Alo content exceed 2.0% which was a former criterion of andic d) The bulk density of almost all the horizons was less than 0.90 g/cm a which is one of the criteria of andic soil properties (ICOMAND 1983(ICOMAND , 1987(ICOMAND , 1988 e) H-1 and S-3 exhibited andic soil properties throughout a continuous thickness of 35 cm starting within 25 cm of the surface, which indicates the presence of Andisol (ICOMAND 1988). In view of the dominance of 2 : 1-2 : 1 : 1 clay minerals in the clay fraction (Hirai et al 1989), the brown forest soil (S-3) may be similar to a non-allophanic Andisol (Baham and Simonson 1985;Shoji et al 1985Shoji et al , 1987Hunter et al 1987).…”

“…In the preceding papers we analyzed the distribution pattern of sesquioxides and clay mineralogical alteration in the profile of the brown forest soils and the podzolic soils in northern Kyoto in the southwestern part of Honshu and pointed out that the brown forest soils there were subjected to weak podzolization (Hirai et al 1988(Hirai et al , 1989.…”