Geoscience Reference
In-Depth Information
50
y = 0.8006x - 10.322
R
2
= 0.8429
40
30
20
10
0
0
10
30
Water Content (g kg
-1
)
20
40
50
60
fIGURe 13.1
The relation between soil organic matter (SOM) and soil water content (
n
= 154).
tAble 13.2
Selected Soil properties Grouped on the basis of Measured eM
h
,
with Intervals Commonly Used for Soil Survey Maps in norway*
Soil organic Matter
Silt
total Sand
g kg
−1
g kg
−1
g kg
−1
eM
h
Interval
mS m
−1
Class
n
Mean
Stdv
n
Mean
Stdv
n
Mean
Stdv
1
0 ≥ EM
H
< 2
38
30.3
a
14.8
5
327
a
36.7
5
568
a
48.0
2
2 ≥ EM
H
< 4
140
71.1
b
28.5
12
372
ab
69.0
12
463
b
93.4
3
4 ≥ EM
H
< 6
75
96.6
c
37.0
11
470
c
40.7
11
310
c
55.6
4
6 ≥ EM
H
< 8
18
133
d
74.8
3
428
bc
51.4
3
373
bc
95.0
5
8 ≥ EM
H
< 10
15
190
e
79.8
3
400
abc
11.5
3
390
bc
26.2
6
10 ≥ EM
H
< 12
15
227
f
88.6
3
490
cd
124.9
3
335
c
17.2
7
12 ≥ EM
H
< 14
7
326
g
68.9
3
576
d
72.4
3
327
c
38.6
*
Number of observations (n), mean, and standard deviation (Stdv) within each group are shown, and
means indicated by the same letter are not significantly different.
correlations were positive, except those between EM
H
and the sand fractions and K-HNO
3
. Mea-
sured EC
a
was unaffected by the clay content.
The soil properties selected for testing the commercial soil survey practice were soil water
content, ignition loss, soil organic matter, silt content, and all sand fractions except medium sand.
The sand fractions were naturally strongly intercorrelated, as were ignition loss and SOM (data not
shown). However, ignition loss and SOM also correlated strongly with soil water content, as shown
for SOM in Figure 13.1. For convenience, only soil properties having a low intercorrelation are
presented in Table 13.2.
Mean SOM increased with each EM
H
class up to the highest class included in the test, and there
were statistical differences between all seven classes (Table 13.2). The good match between the EC
a
zones (based on the commercial procedure) and the SOM content is illustrated in Figure 13.2. For
ignition loss and soil water content, there were significant differences between six and five of the
