Relations between a Commercial Soil Survey Map Based on Soil Apparent Electrical Conductivity (ECa) and Measured Soil Properties on a Morainic Soil in Southeast Norway - Agricultural Geophysics - page 229

N

EMh (mS/m)

0-2

2-4
4-6
6-8
8-10
10-12
12-14

14-16
16-18
18-20

100 0 100 Meters

N

SOM (%)

0-3
3-6
6-9
9-12
12-15
15-18
18-21
21-24
24-27
27-30
30-33

100 0 100Meters

fIGURe 13.2 Map showing EM H , using the standard procedure used in Norway for commercial soil survey
with the EM-EC a method (above), and measured soil organic matter (SOM) content. Soil sample locations are
indicated by black dots.

classes, respectively (data not shown). Mean silt content increased from the lowest to the highest class
but showed a decrease from class 3 to 5. A similar trend was seen for the sand fractions (for total sand
see Table 13.2), but with opposite signs, as the sand content decreased from the lowest to the highest
class. Hence, none of the texture fractions were unambiguously reflected by the soil survey map.

13.4 dISCUSSIon
There were significant correlations between apparent electrical conductivity (EC a ) and all the tex-
ture fractions except for clay content. This exception is not typical, because EC a is normally strongly