Agriculture Reference
In-Depth Information
(continued)
To convert column
1 into column 2,
multiply by
To convert column
2 to column 1,
multiply by
Column 1, SI unit
Column 2, non-SI unit
Quantities per unit area
0.893
kilogram/hectare, kg/ha
pound/acre, lb/ac
1.12
0.446
tonne/hectare, t/ha
ton (U.S)/ac, ton/ac
2.24
0.107
liter/hectare, L/ha
gallon/ac
9.35
Miscellaneous
(9/5
o
C) + 32
Celsius,
o
C
b
Fahrenheit,
o
F
5/9 (
o
F - 32)
9.90
megapascal, MPa
atmosphere
0.101
10
Siemen/meter, S/m
millimho/centimeter,
mmho/cm
0.1
a
mega (M),
×
10
6
; kilo (k),
×
10
3
; deci (d),
×
10
-1
; centi (c),
×
10
-2
; milli (m),
×
10
-3
; micro (μ),
×
10
-6
;
nano (n),
×
10
-9
.
b
To convert from degrees Celsius to degrees Kelvin, add 273.
Appendix 2 The Relationship between Electrical Conductivity 1 to 5 Soil-to-
Water Ratio (
EC
1:5
) and Electrical Conductivity of the Saturation Extract (
EC
e
)
for a Range of Soil Textures
To convert
EC
1:5
values to
EC
e
values, multiply the
EC
1:5
value by the factor
K
in
the table A2.1. The factor decreases as texture increases because, per unit weight of
soil, a clay holds more water at saturation than a sand. The dilution effect on the soil
solution is therefore relatively smaller in a clay soil.
Note that these conversions are likely to overestimate
EC
e
in soil containing salts
such as gypsum, because such salts dissolve to some extent when the soil is suspended
1 to 5 in water.
Table A2.1
Factors to Convert
EC
1:5
to
EC
e
Values According to Soil Texture
Soil texture
Factor
K
Loamy sand
13
Silty loam
12
Sandy loam, loam
11
Sandy clay loam, clay loam
9
Sandy clay, loamy clay, light clay
7
Medium to heavy clay
5
Adapted from White (2003).
