Agriculture Reference
In-Depth Information
Macro- and Micronutrients, Their Chemical Symbols, and Common Ionic Forms in the Soil
Table 4.1
Macronutrient
Common Ionic
Micronutrient
Common Ionic
1,000 mg/kg)
a
100 mg/kg)
a
(
Forms in Soil
(
Forms in Soil
HCO
3
, CO
3
Carbon (C)
2
Iron (Fe)
Fe
3+
(sometimes Fe
2
)
Mn
4
(sometimes Mn
2
)
Zn
2
H
Hydrogen (H)
Manganese (Mn)
Oxygen (O)
H
2
O and many ions,
e.g., OH
, NO
3
,
SO
4
2
NH
4
, NO
3
Zinc (Zn)
Cu
2
B(OH)
4
MoO
4
2
Nitrogen (N)
Phosphorus (P)
Sulfur (S)
Calcium (Ca)
Magnesium (Mg)
Potassium (K)
Chlorine (Cl)
Copper (Cu)
Boron (B)
Molybdenum
(Mo)
H
2
PO
4
, HPO
4
SO
4
2
Ca
2
Mg
2
K
Cl
2
a
Units of measurement are discussed in box 4.1.
Trace elements in the soil are normally derived from the parent material. Ex-
amples of concentrations of trace elements in soils derived from different parent
materials are given in table 4.2. The rock
serpentinite
forms the parent material of
soils at the northern end of the Napa Valley, California. Soils formed on serpen-
tinite adversely affect the growth of grapevines because of their high Ni content
and also because the macronutrient Mg is too high relative to Ca and K. Trace
elements are also deposited naturally from the atmosphere, especially from vol-
canic eruptions and in dust and sea spray. In the twentieth century, however, an-
thropogenic sources of trace elements have increased markedly, especially from
mining, industrial processing, motor vehicles, agricultural chemicals, and urban
waste. These sources have increased trace element loadings in soil-plant systems,
via the atmosphere and through direct solid and/or liquid applications (e.g., spread-
Trace Element Contents
a
of Soils Formed on Different Rock Types
Table 4.2
Limestone and
Element
Dolomite
Serpentinite
Andesite
Granite
Sandstone
Basic
(ßßßßßßßßßßßßßßßßßßßßßßßßßß!
Acidic
Co
0.2
160
16
4
4
Ni
40
1600
20
20
30
Cr
22
6000
120
10
60
Mo
0.8
2
2
2
2
Cu
8
40
20
20
20
Mn
2200
6000
1600
1400
400
Pb
18
2
12
36
24
a
In kg/ha
Source:
Compiled from Mason (1966) and White (1997)
