Fukuoka Plain. These soils have a coarse texture, contain 1:1
clay minerals, and have a weak buffering capacity. (4) Soils
in the Hitoyoshi and Miyakonojo Basins. These soils contain
1:1 clay minerals and amorphous clay minerals influenced
by volcanic ash and have a high phosphate adsorption
coefficient. Fluvic soils are subdivided taxonomically into
Fluvic Paddy soils, Gley Fluvic soils, Gray Fluvic soils,
Brown Fluvic soils, and so on, based on the effects of irrigation water and groundwater. Fluvic Paddy soils and
Brown Fluvic soils are distributed in natural levees, alluvial
fans, and in high altitude areas in the Chikugo, Kuma, and
Oyodo river basins. Gray Fluvic soils are distributed in the
flat areas of the Chikushi, Kumamoto, and Yatsushiro Plains.
Gley Fluvic soils are widely distributed in reclaimed areas
such as the Ariake Sea and the Shiranui Coast and are also
distributed in mountainous areas or valley bottom plains
between terraces (Hamazaki 2004). Gley Fluvic soils may be
accompanied by a peat layer, a black mud layer, and in some
cases, an acid sulfate soil layer in the lower layer.
Soils of the Fluvic soil great group are mainly used as
paddy fields. There are many paddy fields reclaimed around
the Ariake Sea in northern Kyushu, and the soil productivity
is moderate to good. In addition to paddy rice (Oryza sativa
L.), wheat (Triticum aestivum L.), soybean (Glycine max L.
Merril, strawberry (Fragaria ananassa DUCHESNE), and
eggplant (Solanum melongena) and onion (Allium cepa L.)
is cultivated in the Chikushi Plain, and cucumber (Cucumis
sativus L.) and tomato (Solanum lycopericum L.) are cultivated in the Miyazaki Plain.
(2) Andosols
Soils of this great group are distributed in the areas covered
with volcanic ejecta around Mt. Aso, Mt. Kuju, Mt. Unzen,
Mt. Sakurajima, Mt. Kirishima, and Mt. Kaimon. Uncultivated Andosols are generally rich in humus, the content of
which may exceed 30% (Miyazawa 1986). Soil layers with
properties such as high humus content and high phosphate
absorption coefficient were generated at the rim of Mt. Aso
10 kya and at the western foot of the rim of Mt. Aso about
24 kya (Yamada and Kubotera 1994). On the other hand,
Non-Allophanic Andosols showing strong acidity are scattered around northern Kyushu. Furthermore, it was recently
revealed that Non-Allophanic Andosols are also widely
distributed in the Kuju Plateau in central Kyushu (Kubotera
et al. 2013).
Andosols have low base saturation and a high phosphate
absorption coefficient, and are small in volume weight and
rich in pores. Therefore, these soils have good water retention and drainage, have low bulk densities, and allow
exceptionally easy cultivation. The agricultural land on
Andosols is used for upland fields, forage fields, orchards,
and tea fields, as this soil type is widely distributed at the feet
of volcanic mountains and plateaus.
(3) Red-Yellow soils
Red-Yellow soils are distributed on hills and tableland in
northern and central Kyushu and on mountainous hills and
terraces in the Nansei Islands. Red-Yellow soils are derived
from various kinds of rocks and strata such as basalt,
andesite, crystalline schist, granite, Paleogene and Neogene
sedimentary rocks, Pleistocene strata, and so on.
Red-Yellow soils in northern Kyushu are distributed only in
high terraces and are considered to be the paleosol formed in
the Pleistocene warm period (about 120–130 kya) (Matsui
and Kato 1962). On the other hand, Red-Yellow soils in the
central and the southern part of the Nansei Islands are
considered to have formed under the current climate. Some
Red-Yellow soils derived from andesite are difficult to form
under the current warm and humid climatic conditions,
which causes moderate soil weathering. It has been pointed
out that such soils may have been formed by post-volcanic
action, such as the intense oxidation or alteration of the soil
host rock during or after the lava cooling process (Yoshida
et al. 1974). Furthermore, it has been pointed out that the
formation of these soils is influenced by eolian dust from the
Asian continent based on evidence about the grain size and
the chemical properties of the quartz grains contained in the
soil (Mizota et al. 1992).
Since Red-Yellow soils are distributed in plateaus and
hills, are weakly acidic, and have a low nutrient content and
low nutrient-holding capacity; they are mainly used as upland fields, orchards, and tea fields. In the central and the
southern part of the Nansei Islands, sugarcane, pineapple
(Ananas comosus (L.) Merr.), and citrus fruits are cultivated.
10.1.3 Properties and Management of Local
Problem Soils
Kyushu has many volcanoes, and volcanic soils are therefore
widely distributed. Andosols derived from fine volcanic ash
are suitable for upland farming due to their excellent physical properties. However, some volcanic ejecta have
unsuitable physical properties. In 1952, a law for the
enhancement of disaster prevention and soil improvement
for these problematic soils was enforced by the Japanese
government. In Kyushu, the soils described below are subject to this law.
332
Y. Arakawa et al.
clay minerals, and have a weak buffering capacity. (4) Soils
in the Hitoyoshi and Miyakonojo Basins. These soils contain
1:1 clay minerals and amorphous clay minerals influenced
by volcanic ash and have a high phosphate adsorption
coefficient. Fluvic soils are subdivided taxonomically into
Fluvic Paddy soils, Gley Fluvic soils, Gray Fluvic soils,
Brown Fluvic soils, and so on, based on the effects of irrigation water and groundwater. Fluvic Paddy soils and
Brown Fluvic soils are distributed in natural levees, alluvial
fans, and in high altitude areas in the Chikugo, Kuma, and
Oyodo river basins. Gray Fluvic soils are distributed in the
flat areas of the Chikushi, Kumamoto, and Yatsushiro Plains.
Gley Fluvic soils are widely distributed in reclaimed areas
such as the Ariake Sea and the Shiranui Coast and are also
distributed in mountainous areas or valley bottom plains
between terraces (Hamazaki 2004). Gley Fluvic soils may be
accompanied by a peat layer, a black mud layer, and in some
cases, an acid sulfate soil layer in the lower layer.
Soils of the Fluvic soil great group are mainly used as
paddy fields. There are many paddy fields reclaimed around
the Ariake Sea in northern Kyushu, and the soil productivity
is moderate to good. In addition to paddy rice (Oryza sativa
L.), wheat (Triticum aestivum L.), soybean (Glycine max L.
Merril, strawberry (Fragaria ananassa DUCHESNE), and
eggplant (Solanum melongena) and onion (Allium cepa L.)
is cultivated in the Chikushi Plain, and cucumber (Cucumis
sativus L.) and tomato (Solanum lycopericum L.) are cultivated in the Miyazaki Plain.
(2) Andosols
Soils of this great group are distributed in the areas covered
with volcanic ejecta around Mt. Aso, Mt. Kuju, Mt. Unzen,
Mt. Sakurajima, Mt. Kirishima, and Mt. Kaimon. Uncultivated Andosols are generally rich in humus, the content of
which may exceed 30% (Miyazawa 1986). Soil layers with
properties such as high humus content and high phosphate
absorption coefficient were generated at the rim of Mt. Aso
10 kya and at the western foot of the rim of Mt. Aso about
24 kya (Yamada and Kubotera 1994). On the other hand,
Non-Allophanic Andosols showing strong acidity are scattered around northern Kyushu. Furthermore, it was recently
revealed that Non-Allophanic Andosols are also widely
distributed in the Kuju Plateau in central Kyushu (Kubotera
et al. 2013).
Andosols have low base saturation and a high phosphate
absorption coefficient, and are small in volume weight and
rich in pores. Therefore, these soils have good water retention and drainage, have low bulk densities, and allow
exceptionally easy cultivation. The agricultural land on
Andosols is used for upland fields, forage fields, orchards,
and tea fields, as this soil type is widely distributed at the feet
of volcanic mountains and plateaus.
(3) Red-Yellow soils
Red-Yellow soils are distributed on hills and tableland in
northern and central Kyushu and on mountainous hills and
terraces in the Nansei Islands. Red-Yellow soils are derived
from various kinds of rocks and strata such as basalt,
andesite, crystalline schist, granite, Paleogene and Neogene
sedimentary rocks, Pleistocene strata, and so on.
Red-Yellow soils in northern Kyushu are distributed only in
high terraces and are considered to be the paleosol formed in
the Pleistocene warm period (about 120–130 kya) (Matsui
and Kato 1962). On the other hand, Red-Yellow soils in the
central and the southern part of the Nansei Islands are
considered to have formed under the current climate. Some
Red-Yellow soils derived from andesite are difficult to form
under the current warm and humid climatic conditions,
which causes moderate soil weathering. It has been pointed
out that such soils may have been formed by post-volcanic
action, such as the intense oxidation or alteration of the soil
host rock during or after the lava cooling process (Yoshida
et al. 1974). Furthermore, it has been pointed out that the
formation of these soils is influenced by eolian dust from the
Asian continent based on evidence about the grain size and
the chemical properties of the quartz grains contained in the
soil (Mizota et al. 1992).
Since Red-Yellow soils are distributed in plateaus and
hills, are weakly acidic, and have a low nutrient content and
low nutrient-holding capacity; they are mainly used as upland fields, orchards, and tea fields. In the central and the
southern part of the Nansei Islands, sugarcane, pineapple
(Ananas comosus (L.) Merr.), and citrus fruits are cultivated.
10.1.3 Properties and Management of Local
Problem Soils
Kyushu has many volcanoes, and volcanic soils are therefore
widely distributed. Andosols derived from fine volcanic ash
are suitable for upland farming due to their excellent physical properties. However, some volcanic ejecta have
unsuitable physical properties. In 1952, a law for the
enhancement of disaster prevention and soil improvement
for these problematic soils was enforced by the Japanese
government. In Kyushu, the soils described below are subject to this law.
332
Y. Arakawa et al.