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Table 1. Soil properties.
Location
Land use
Soil type
Soil name
Abbreviation
abbreviated
of
soil name
Ammonium
Nitrate
( μμgN
g N g -1 soil)
Oak forest
Cambisol
TUATFF
9.7
20.3
Grassland
Andosol
TUATAA
6.8
53.9
Arable
Acrisol
NUFA1
3.3
50.0
Arable
Acrisol
NUFA2
3.2
76.7
Arable
Acrisol
NUFA3
17.5
Pine forest
Cambisol
NUFF
11.5
0.4
Tamdao , Vietnam
Arable
Cambisol
VTA
2.7
15.7
Leyte , Philippines
Arable
Cambisol
PHLA
1.9
23.7
FM*1 Tsukui, Tokyo University of Agriculture
and Technology, Kanagawa Pref., Japan
The Nagoya University Farm, Aichi Pref.,
Japan
*1: Field Museum Tsukui, Field Science and Education Center
Yanai (Table 1)
684
(a) NUFA3
(e) NUFA1
950
150
850
100
750
50
650
0
550
0
3
6
9
0
12
350
Nitrate content (μg N g-1 soil)
15
30
45
60
15
30
45
60
75
(f) NUFF
(b) NUFA2
50
300
40
250
30
200
20
150
10
100
0
50
0
3
6
9
0
12
(c) TUATA
75
90
(g) TUATF
250
280
200
230
150
180
130
100
80
50
30
0
0
3
6
9
12
15
(d) PHLA
0
15
30
15
30
45
60
75
(h) VTA
200
100
160
80
120
60
80
40
40
20
0
0
0
3
6
9
12
15
18
21
24
0
45
60
Incubation period (day)
Fig. 1. Time course of nitrate content in soils. Samples were incubated at 27℃ to adjust the
moisture content to 60 % of maximum water-holding capacity with (closed symbols) or
without (open symbols) 200 μg N of ammonium sulfate g-1dry soil in the soils subjected to
the freeze-thaw cycles (diamond symbols with a solid line) or kept at 4℃ constant
temperature (unfrozen control; square symbols with a dotted line). Each value shows mean
and SD (n = 2).
Yanai (Fig. 1)
75
Nitrate content （μg N g-1dry soil）
(NH4)2SO4
AAA
35
CH
3COONH4
BBB
NH
4HCO3
CCC
e
(a) VTA
80
d
d
(B) TUATF
c
28
c
60
21
Control
DDD(not added)
c
120
(C) TUATA c
b
c
b
90
b
40
a
a
14
7
20
30
0
0
0
0
15
0
15
a
a
60
0
3
Incubation period (day)
Fig. 2. Effects of counter-anions of ammonium salts (200 μg N g-1dry soil addition) on
nitrification in different soils: (a) VT A, (b) TUATF and (c) TUATA. Each value shows mean and
SD (n = 2). For each soil, values marked with different letters are si gnificantly different,
according to Tukey’s multiple comparisons (P < 0.05).
Yanai (Fig. 2)
7.0
pH (KCl)
6.0
5.8 a
5.0
4.6 b
4.0
3.9 c
3.0
2.0
X
Y
Z
Effect of soil freeze-thaw cycles on nitrification
Fig. 3. Relationship between soil pH (KCl) and the
responses of the nitrification potential of soils to the
soil freeze-thaw cycles; X: not inhibited (NUF A3,
NUFA2 and TUATA); Y: significantly inhibited
(PHLA and TUATF); Z: undetectable even in the
unfrozen control (VT A, NUFA1 and NUFF). Each
value shows mean and SD. Values marked with
different letters are significantly different, according
to Fisher’s LSD (P < 0.05). Data of pH (KCl) were
cited from Table 1 in Yanai et al. (submitted to Soil
Sci. Plant Nutr.).
Yanai (Fig. 3)

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