Campbell Scientific 253 253-L and 257-L (Watermark 200) Soil Matric Potential - Page 24

TABLE 7-3., Comparison of, Estimated Soil Water Potential, and R, at 21°C, kPa Non, Linear, Equation

Get Campbell Scientific 253 PDF manuals and user guides View all Campbell Scientific 253 manuals
Add to My Manuals
Save this manual to your list of manuals

Page 24 highlights

253-L and 257-L Soil Matric Potential Sensors 7.2.3.2 Non-Linear Relationship For more precise work, calibration and temperature compensation in the range of 10 to 100 kPa has been refined by Thompson and Armstrong (1987), as defined in the non-linear equation, SWP = Rs 0.01306[1.062(34.21 − Ts + 0.01060Ts 2 ) − Rs ] where SWP is soil water potential in kPa TABLE 7-3. Comparison of Estimated Soil Water Potential and Rs at 21°C kPa (NonLinear Equation) -9 -14 -20 -27 -35 -45 -56 -69 -85 -105 kPa (Linear Equation) -3.7 -11 -18 -26 -33 -41 -48 -56 -63 -70 -78 -85 -92 -99 -107 -115 -122 -129 -144 -159 -174 -188 -199 (Rs) kOhms 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 12.00 13.00 14.00 15.00 16.00 17.00 18.00 20.00 22.00 24.00 26.00 27.50 18

  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
  • 11
  • 12
  • 13
  • 14
  • 15
  • 16
  • 17
  • 18
  • 19
  • 20
  • 21
  • 22
  • 23
  • 24
  • 25
  • 26
  • 27
  • 28
  • 29
  • 30
  • 31
  • 32
  • 33
  • 34
  • 35
  • 36
253-L and 257-L Soil Matric Potential Sensors
7.2.3.2 Non-Linear Relationship
For more precise work, calibration and temperature compensation in the range
of 10 to 100 kPa has been refined by Thompson and Armstrong (1987), as
defined in the non-linear equation,
]
)
01060
.
0
21
.
34
(
062
.
1
[
01306
.
0
s
s
s
R
T
T
−
+
−
2
s
R
SWP
=
where SWP is soil water potential in kPa
TABLE 7-3.
Comparison of
Estimated Soil Water Potential
and R
s
at 21°C
kPa (Non-
Linear
Equation)
kPa
(Linear
Equation)
(R
s
)
kOhms
–3.7
1.00
–9
–11
2.00
–14
–18
3.00
–20
–26
4.00
–27
–33
5.00
–35
–41
6.00
–45
–48
7.00
–56
–56
8.00
–69
–63
9.00
–85
–70
10.00
–105
–78
11.00
–85
12.00
–92
13.00
–99
14.00
–107
15.00
–115
16.00
–122
17.00
–129
18.00
–144
20.00
–159
22.00
–174
24.00
–188
26.00
–199
27.50
18