Agriculture Reference
In-Depth Information
(a)
(b)
(c)
(d)
b
HS
=
0, CEC
=
0,
[X
−
]
L
b
HS
=
15, CEC
=
35,
[X
−
]
L
b
HS
=
50, CEC
=
35,
[X
−
]
L
b
HS
=
50, CEC
=
10,
[X
−
]
L
=
0
=
20
=
20
=
10
4.0
18
8.0
16
Fe
2
+
3.5
7.5
Fe
2
+
14
Fe
2
+
3.0
7.0
pH
12
pH
pH
2.5
6.5
10
pH
2.0
8
6.0
Fe
2
+
6
1.5
5.5
4
1.0
5.0
2
pe
pe
0.5
O
2
4.5
pe
pe
0
O
2
O
2
O
2
0.0
−
2
4.0
0
2
4
6
8
10121416 0
2
4
6
8
10121416 0
2
4
6
8
10121416 0
2
4
6
8
10121416
CH
2
O oxidized (mmol kg
−
1
)
Figure 4.7
Calculated changes in pe, pH, [O
2
]and[Fe
2
+
] in an idealized soil during reduction. Mineral phases Fe(OH)
3
and Fe
3
(
OH
)
8
.
Parameters for pH buffering and cation exchange differ between (a) - (d) as indicated. Units of
b
HS
(soil pH buffer power), mmol kg
−
1
pH
−
1
;
CEC (initial cation exchange capacity), cmol
c
kg
−
1
;and[X
−
]
L
(concentration of non-carbonate anions), mM. CO
2
pressure
=
10 kPa,
θ
=
0
.
6,
ρ
=
1
.
0, initial pH
=
4
.
5