Eutrosols exhibit various colors, such as chocolate,
yellowish-brown, reddish-brown, and dark brown. Magnesian Eutrosols are generally distributed on serpentine and
Calcareous Eutrosols are mainly distributed on limestone.
Calcareous Eutrosols are one of the major soils on the
Nansei Islands, which lie in a subtropical area where coral
reef terraces are well-developed. It has been suggested that
the Calcareous Eutrosols in this area formed from the residue
of limestone (Nagatsuka et al. 1983). However, Inoue et al.
(1993) estimated that the parent material of this soil was
mainly eolian dust which was transported from continental
China including East China Sea sediments in dry periods of
glacial age. However, there is still no clear conclusion as to
the parent material of Calcareous Eutrosols, and the elucidation of the potential contribution of eolian dust as a parent
material is a subject to be studied in the future.
4.8.5 Land Use
In the case of Magnesian Eutrosols, due to the imbalance of
base cations and the influence of heavy metals (nickel,
cobalt, manganese), the growth of trees is usually not good,
and unique vegetation with characteristic species of dwarf
forests is observed in these soils. However, in some areas,
these mineral-rich soils are suitable for agricultural use as
orchards (mandarin oranges) and paddy fields.
On the other hand, the Calcareous Eutrosols occurring on
limestone in the Nansei Islands are mainly used for sugar
cane cultivation. The subsurface soil has a high clay content,
is densic, and has low permeability. As a result, water percolates across the slope and flows out of sugar cane fields
through cracks in the limestone bedrock, which makes the
soils susceptible to drought.
4.8.6 Future Challenges
Volcanogenous Dark Red soil formed by hydrothermal
metamorphism was classified as Dark Red soil in past soil
classification systems (Forest Soil Division 1976; Cultivated
Soil Classification Committee 1995). According to the Soil
Classification System of Japan, Volcanogenous Dark Red
soil is classified not into the Eutrosol soil great group, but
rather into the Red-Yellow or Brown Forest soil great
group. The formation process of this soil is different from
that of Red-Yellow soils or Brown Forest soils, and therefore, we need to further consider how to classify acidic
dark-reddish soils such as Volcanogenous Dark Red soil in
the new classification system. Further data collection is
needed to classify these soils.
4.9 Brown Forest Soils
In mountainous, humid parts of Japan, Brown Forest soils,
which are relatively young soils, are widely distributed. In
the Japanese archipelago, which stretches for over 3000 km
in a north-to-southwardly direction and experiences climatic
zones ranging from subarctic to subtropical, Brown Forest
soils have a wide range of soil properties resulting from
various soil-forming factors of other soil great groups, such
as podzolization, including not only those having a cambic
horizon but also those having an argic horizon. The difference between Brown Forest soils and Regosols is that they
have a cambic horizon or argic horizon of sufficient thickness. Most Brown Forest soils are acidic or weakly acidic
due to the leaching of base elements under a warm and
humid climate condition. Most forest lands in Japan are
covered by Brown Forest soils.
Table 4.6 Correlation of soil
classification system for Eutrosols
Soil classification system of Japan (2017)
WRB (2014)
Soil Taxonomy (2014)
Eutrosols
Luvisols, Cambisols
Udalfs, Udepts
Magnesian
Luvisols, Cambisols
Udalfs, Udepts
Argic
Leptic Luvisols (Chromic)
Leptic Luvisols (Rhodic)
Haplic Luvisols (Chromic)
Haplic Luvisols (Rhodic)
Typic Paleudalfs
Typic Rhodualfs
Typic Hapludalfs
Haplic
Leptic Cambisols (Eutric)
Haplic Cambisols (Eutric)
Lithic Eutrudepts
Typic Eutrudepts
Calcareous
Luvisols, Cambisols
Udalfs, Udepts
Argic
Leptic Luvisols
Haplic Luvisols
Typic Paleudalfs
Typic Rhodualfs
Typic Hapludalfs
Haplic
Leptic Cambisols (Eutric)
Haplic Cambisols (Eutric)
Lithic Eutrudepts
Typic Eutrudepts
4 Major Soil Types
113
yellowish-brown, reddish-brown, and dark brown. Magnesian Eutrosols are generally distributed on serpentine and
Calcareous Eutrosols are mainly distributed on limestone.
Calcareous Eutrosols are one of the major soils on the
Nansei Islands, which lie in a subtropical area where coral
reef terraces are well-developed. It has been suggested that
the Calcareous Eutrosols in this area formed from the residue
of limestone (Nagatsuka et al. 1983). However, Inoue et al.
(1993) estimated that the parent material of this soil was
mainly eolian dust which was transported from continental
China including East China Sea sediments in dry periods of
glacial age. However, there is still no clear conclusion as to
the parent material of Calcareous Eutrosols, and the elucidation of the potential contribution of eolian dust as a parent
material is a subject to be studied in the future.
4.8.5 Land Use
In the case of Magnesian Eutrosols, due to the imbalance of
base cations and the influence of heavy metals (nickel,
cobalt, manganese), the growth of trees is usually not good,
and unique vegetation with characteristic species of dwarf
forests is observed in these soils. However, in some areas,
these mineral-rich soils are suitable for agricultural use as
orchards (mandarin oranges) and paddy fields.
On the other hand, the Calcareous Eutrosols occurring on
limestone in the Nansei Islands are mainly used for sugar
cane cultivation. The subsurface soil has a high clay content,
is densic, and has low permeability. As a result, water percolates across the slope and flows out of sugar cane fields
through cracks in the limestone bedrock, which makes the
soils susceptible to drought.
4.8.6 Future Challenges
Volcanogenous Dark Red soil formed by hydrothermal
metamorphism was classified as Dark Red soil in past soil
classification systems (Forest Soil Division 1976; Cultivated
Soil Classification Committee 1995). According to the Soil
Classification System of Japan, Volcanogenous Dark Red
soil is classified not into the Eutrosol soil great group, but
rather into the Red-Yellow or Brown Forest soil great
group. The formation process of this soil is different from
that of Red-Yellow soils or Brown Forest soils, and therefore, we need to further consider how to classify acidic
dark-reddish soils such as Volcanogenous Dark Red soil in
the new classification system. Further data collection is
needed to classify these soils.
4.9 Brown Forest Soils
In mountainous, humid parts of Japan, Brown Forest soils,
which are relatively young soils, are widely distributed. In
the Japanese archipelago, which stretches for over 3000 km
in a north-to-southwardly direction and experiences climatic
zones ranging from subarctic to subtropical, Brown Forest
soils have a wide range of soil properties resulting from
various soil-forming factors of other soil great groups, such
as podzolization, including not only those having a cambic
horizon but also those having an argic horizon. The difference between Brown Forest soils and Regosols is that they
have a cambic horizon or argic horizon of sufficient thickness. Most Brown Forest soils are acidic or weakly acidic
due to the leaching of base elements under a warm and
humid climate condition. Most forest lands in Japan are
covered by Brown Forest soils.
Table 4.6 Correlation of soil
classification system for Eutrosols
Soil classification system of Japan (2017)
WRB (2014)
Soil Taxonomy (2014)
Eutrosols
Luvisols, Cambisols
Udalfs, Udepts
Magnesian
Luvisols, Cambisols
Udalfs, Udepts
Argic
Leptic Luvisols (Chromic)
Leptic Luvisols (Rhodic)
Haplic Luvisols (Chromic)
Haplic Luvisols (Rhodic)
Typic Paleudalfs
Typic Rhodualfs
Typic Hapludalfs
Haplic
Leptic Cambisols (Eutric)
Haplic Cambisols (Eutric)
Lithic Eutrudepts
Typic Eutrudepts
Calcareous
Luvisols, Cambisols
Udalfs, Udepts
Argic
Leptic Luvisols
Haplic Luvisols
Typic Paleudalfs
Typic Rhodualfs
Typic Hapludalfs
Haplic
Leptic Cambisols (Eutric)
Haplic Cambisols (Eutric)
Lithic Eutrudepts
Typic Eutrudepts
4 Major Soil Types
113