Quantifying Plant Water Use in the Native Coteau Rangelands of North Dakota


 

Table 2. The Campbell equation (C) and the Van Genuchten and Nielsen equation (GN) as fitted to the experimentally measured soil water characteristic curves for 12 samples from CGREC. Also shown are the root mean square deviations (RMSD*) between the measured and fitted points (in terms of q) for each of the samples. In the fitting procedure, the minimum and maximum values of different parameters are assumed to be within the following range: ymax (-10 – -1), qmax (0.25 – 0.60), q (1 – 20), qr (0.001 – 0.1), n (0.5 – 6), m (0.08 – 1).

 

Campbell Equation

Van Genuchten & Nielsen Equation

Site

Depth

   (in)

ymax (J kg –1)

 qmax(v/v)

q

RMSD

ymax (J kg –1)

qmax(v/v)

qr(v/v)

n

 m

RMSD

Non-grazed

0-6

-3.404

 0.368

9.795

0.025

-1.739

0.518

0.100

1.224

0.183

0.013

Non-grazed

6-12

-4.918

 0.395

8.209

0.026

-4.083

0.515

0.100

1.249

0.199

0.008

Non-grazed

12-18

-8.669

 0.398

6.085

0.009

-2.219

0.568

0.081

1.255

0.203

0.007

Non-grazed

18-24

-3.438

 0.593

4.592

0.036

-12.569

0.416

0.010

1.205

0.170

0.008

Non-grazed

24-30

-9.892

 0.524

4.897

0.007

-9.232

0.591

0.100

1.327

0.246

0.014

Non-grazed

30-36

-9.943

 0.539

4.543

0.025

-5.764

0.600

0.090

1.296

0.228

0.013

Non-grazed

36-48

-4.556

 0.523

6.038

0.030

-8.921

0.597

0.100

1.315

0.240

0.011

Non-grazed

48-60

-8.331

 0.596

4.404

0.031

-15.513

0.531

0.010

1.239

0.193

0.012

Moderate

0-6

-4.334

 0.403

7.446

0.011

-1.666

0.515

0.100

1.238

0.192

0.009

Moderate

30-36

-9.599

 0.599

5.812

0.008

-15.488

0.600

0.037

1.214

0.176

0.016

Extreme

0-6

-2.932

 0.360

15.937

0.042

-1.634

0.529

0.097

1.178

0.151

0.012

Extreme

30-36

-9.995

 0.600

5.704

0.012

-24.029

0.600

0.100

1.298

0.230

0.027

* RMSD is calculated as [å((x-x’)2/n)]1/2, where x, x’ and n represent measured, fitted soil water contents and number of points in each curve.

 
Table of contents | Introduction| Methods | Data Analysis and Modeling | Results

  
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