Geoscience Reference
In-Depth Information
elevated EC
a
values greater than 200 mS/m and corresponding low yield values below 600 kg/ha
(Figure 20.2).
The map produced from the EC
a
data (Figure 20.2a) is much more detailed than a standard
soil survey. This information was used to explore variability within potential research plots to
be laid out across the Montana field underneath a newly installed linear move sprinkler system.
Figure 20.3a shows the eight east-west tire tracks for the linear system. The Montana field was
divided into nine plots (85 m wide and 378 m long) called M1 to M9, with each plot further divided
into seven subplots. Mean soil EC
a
and yield values from each of the nine Montana plots are shown
in Figure 20.3b, with their corresponding CV values shown in Figure 20.3c. Two important obser-
vations may be made from Figure 20.3.
M9-1
M8-1
M7-1
M6-1
M5-1
M4-1
M3-1
M2-1
M1-1
M9-2
M8-2
M7-2
M6-2
M5-2
M4-2
M3-2
M2-2
M1-2
M9-3
M8-3
M7-3
M6-3
M5-3
M4-3
M3-3
M2-3
M1-3
M9-4
M8-4
M7-4
M6-4
M5-4
M4-4
M3-4
M2-4
M1-4
M9-5
M8-5
M7-5
M6-5
M5-5
M4-5
M3-5
M2-5
M1-5
M9-6
M8-6
M7-6
M6-6
M5-6
M4-6
M3-6
M2-6
M1-6
M9-7
M8-7
M7-7
M6-7
M5-7
M4-7
M3-7
M2-7
M1-7
(a)
60
6000
Shallow EC
a
Deep EC
a
Yield
50
5000
40
4000
3000
30
20
2000
10
1000
0
0
M9 M8 M7 M6 M5 M4 M3 M2 M1
Plot Number
(b)
80
60
40
20
0
M9 M8 M7 M6 M5 M4 M3 M2 M1
Plot Number
(c)
fIGURe 20.3
(a) Map of research plots and subplots in the irrigated Montana field, (b) mean EC
a
and yield (with
error bars), and (c) coefficient of variation (CV) for each of the nine research plots across the Montana field.
