mainly found in terraces accompanied by Pseudogley soils.
In northern Hokkaido, Stagnogley soils are used as grassland
and upland field because the climate is not suitable for rice
cultivation.
4.7.2 Pseudogley Soils
(1) Properties of Pseudogley soils
Pseudogley soils are distributed in flat or gently sloped terraces, hills, and mountainous areas where water stagnates
seasonally. Unlike Stagnogley soils, in Pseudogley soils the
groundwater table is not always shallow. The soil profile of a
Pseudogley soils is characterized by iron-mottle-rich horizons and compacted layers. The upper parts of the profile
(Bg horizon) have mottled coarse blocky peds with bleached
surfaces, while the lower parts (Cg horizon) have mottled
plate-like blocky peds with bleached surfaces. As the peds of
the Cg horizon are more compact than those of the Bg
horizon, the Cg horizon becomes impermeable and water
seasonally stagnates there; the stagnated water causes soil
reduction and promotes the leaching of iron. In the dry
season, the stagnated water disappears and the soil becomes
drier. As a result, the redox potential of the subsoil increases,
iron is oxidized, and free-iron mottles form (Fig. 4.39).
(2) Physical and chemical properties of Pseudogley soils
As bases are leached, Pseudogley soils show strong acidity
and base saturation is low. The subsoil has a fine texture and
its clay content often exceed 25%. The solid phase ratio is
Table 4.5 Distribution area of
Stagnic soils in Japan (Obara et al
2016)
Region
Stagnic soils (km
2
)
Total
Stagnogley soils
Pseudogley soils
Hokkaido
1500
6
1494
Tohoku
0
0
0
Kanto and Tosan
154
36
117
Hokuriku
748
682
65
Chubu
385
0
385
Kinki
150
0
150
Chugoku and Shikoku
8
0
8
Kyushu
1
0
1
Japan
2946
725
2221
Table 4.4 Physicochemical properties of the Stagnic soils (unpublished data by Monolith data of NIAES)
Depth
BD
Permeability
pH
TC
TN
Exchangeable cation
CEC
BSat
PAbs
H 2 O
KCl
Ca
Mg
K
Na
cm
g cm
−3
m s
−1
g kg
−1
cmol c kg
−1
%
Stagnogley soil at Oshima, Niigata prefecture
0
12
0.71
1.98 E−03
4.5
3.6
37
2.4
12.4
5.2
0.5
0.4
33.7
54.9
1170
12
19
0.96
2.26 E−04
4.5
3.6
29
2.0
13.6
5.5
0.4
0.2
33.6
58.6
1180
19
28
1.25
1.71 E−06
4.9
3.7
5
0.7
14.0
5.7
0.6
0.2
31.9
64.3
1140
28
54
1.25
2.00 E−06
5.0
3.5
2
0.5
17.7
7.9
0.9
0.2
34.6
77.2
1090
54
59
5.8
4.5
1
0.4
17.8
9.5
0.9
0.2
28.1
101.1
950
59
69
1.28
2.03 E−04
5.8
4.8
4
0.6
17.7
8.9
0.8
0.2
29.4
93.9
1210
Pseudogley soil at Mombetsu, Hokkaido
0
14
0.56
4.8
3.8
83
3.6
1.3
1.5
0.7
0.5
26.2
15.3
1620
14
33
1.38
7.00 E−04
5.2
3.8
10
0.6
1.6
1.7
0.4
0.2
16.4
23.6
1130
33
53
1.34
1.00 E−05
5.3
3.7
4
0.3
3.5
2.7
0.2
0.4
17.7
39.0
820
53
83
1.60
4.00 E−06
5.5
3.5
1
0.2
5.4
4.4
0.2
0.5
17.1
61.1
510
83
100
1.71
2.00 E−06
BD bulk density, Bsat base saturation, PAbs phosphorus absorption coefficient
108
Y. Takata et al.
In northern Hokkaido, Stagnogley soils are used as grassland
and upland field because the climate is not suitable for rice
cultivation.
4.7.2 Pseudogley Soils
(1) Properties of Pseudogley soils
Pseudogley soils are distributed in flat or gently sloped terraces, hills, and mountainous areas where water stagnates
seasonally. Unlike Stagnogley soils, in Pseudogley soils the
groundwater table is not always shallow. The soil profile of a
Pseudogley soils is characterized by iron-mottle-rich horizons and compacted layers. The upper parts of the profile
(Bg horizon) have mottled coarse blocky peds with bleached
surfaces, while the lower parts (Cg horizon) have mottled
plate-like blocky peds with bleached surfaces. As the peds of
the Cg horizon are more compact than those of the Bg
horizon, the Cg horizon becomes impermeable and water
seasonally stagnates there; the stagnated water causes soil
reduction and promotes the leaching of iron. In the dry
season, the stagnated water disappears and the soil becomes
drier. As a result, the redox potential of the subsoil increases,
iron is oxidized, and free-iron mottles form (Fig. 4.39).
(2) Physical and chemical properties of Pseudogley soils
As bases are leached, Pseudogley soils show strong acidity
and base saturation is low. The subsoil has a fine texture and
its clay content often exceed 25%. The solid phase ratio is
Table 4.5 Distribution area of
Stagnic soils in Japan (Obara et al
2016)
Region
Stagnic soils (km
2
)
Total
Stagnogley soils
Pseudogley soils
Hokkaido
1500
6
1494
Tohoku
0
0
0
Kanto and Tosan
154
36
117
Hokuriku
748
682
65
Chubu
385
0
385
Kinki
150
0
150
Chugoku and Shikoku
8
0
8
Kyushu
1
0
1
Japan
2946
725
2221
Table 4.4 Physicochemical properties of the Stagnic soils (unpublished data by Monolith data of NIAES)
Depth
BD
Permeability
pH
TC
TN
Exchangeable cation
CEC
BSat
PAbs
H 2 O
KCl
Ca
Mg
K
Na
cm
g cm
−3
m s
−1
g kg
−1
cmol c kg
−1
%
Stagnogley soil at Oshima, Niigata prefecture
0
12
0.71
1.98 E−03
4.5
3.6
37
2.4
12.4
5.2
0.5
0.4
33.7
54.9
1170
12
19
0.96
2.26 E−04
4.5
3.6
29
2.0
13.6
5.5
0.4
0.2
33.6
58.6
1180
19
28
1.25
1.71 E−06
4.9
3.7
5
0.7
14.0
5.7
0.6
0.2
31.9
64.3
1140
28
54
1.25
2.00 E−06
5.0
3.5
2
0.5
17.7
7.9
0.9
0.2
34.6
77.2
1090
54
59
5.8
4.5
1
0.4
17.8
9.5
0.9
0.2
28.1
101.1
950
59
69
1.28
2.03 E−04
5.8
4.8
4
0.6
17.7
8.9
0.8
0.2
29.4
93.9
1210
Pseudogley soil at Mombetsu, Hokkaido
0
14
0.56
4.8
3.8
83
3.6
1.3
1.5
0.7
0.5
26.2
15.3
1620
14
33
1.38
7.00 E−04
5.2
3.8
10
0.6
1.6
1.7
0.4
0.2
16.4
23.6
1130
33
53
1.34
1.00 E−05
5.3
3.7
4
0.3
3.5
2.7
0.2
0.4
17.7
39.0
820
53
83
1.60
4.00 E−06
5.5
3.5
1
0.2
5.4
4.4
0.2
0.5
17.1
61.1
510
83
100
1.71
2.00 E−06
BD bulk density, Bsat base saturation, PAbs phosphorus absorption coefficient
108
Y. Takata et al.