Vereecken et al. soil-moisture retention regressions for Belgian soils.¶
Source¶
Vereecken, H., Maes, J., Feyen, J., & Darius, P. (1989). Estimating the soil moisture retention characteristic from texture, bulk density, and carbon content. Soil Science, 148(6), 389-403.
DOI: 10.1097/00010694-198912000-00001
Scope¶
Territory: Belgian territory north of the river axis Samber and Meuse
Dataset: 182 horizons from 40 important Belgian soil series, with textures ranging from sand to heavy clay.
Functions¶
calc_ptf_vereecken1989¶
Estimate four parameters of the reduced van Genuchten moisture-retention model from broad texture fractions, bulk density, and carbon content.
Status: implemented
Prediction target: Residual and saturated volumetric water content and the alpha and n shape parameters of the van Genuchten model with m equal to 1.
Models: \(h(\theta)\) — van Genuchten moisture-retention model with m = 1
Inputs¶
| Name | Type | Unit | Domain | Description |
|---|---|---|---|---|
sand | number | % | 5.60 <= value <= 97.80 | Sand content in the 50-2000 micrometre particle-size fraction. |
clay | number | % | 0 <= value <= 54.46 | Clay content in the less-than-2-micrometre particle-size fraction. |
carbon | number | % | 0.01 <= value <= 6.60 | Carbon content determined by the Walkley-Black method. |
bulk_density | number | g/cm^3 | 1.040 <= value <= 1.730 | Dry bulk density measured after drying undisturbed 100-cm^3 cores for 24 hours at 105 degrees Celsius. |
Outputs¶
| Name | Unit | Domain | Description |
|---|---|---|---|
theta_r | cm^3/cm^3 | 0 <= value <= 1 | Residual volumetric soil water content. |
theta_s | cm^3/cm^3 | 0 <= value <= 1 | Saturated volumetric soil water content. |
alpha | cm^-1 | value > 0 | Shape parameter of the van Genuchten moisture-retention model. |
n | dimensionless | value > 0 | Shape parameter of the van Genuchten moisture-retention model. |
Note
Table 7 reports regressions for theta_s, theta_r, log(alpha), and log(n) using broad particle-size fractions, carbon content, and bulk density.
Note
The paper accepts fitted n values below 1 because constraining n above 1 gave poorer descriptions for many of the measured curves.
Warning
The bulk-density maximum is reviewed as 1.730 g/cm^3 because the supplied transcription's 1.230 value is inconsistent with the reported mean.
calc_ptf_vereecken1989_detailed¶
Estimate van Genuchten parameters from nine particle-size fractions and particle-size distribution descriptors.
Status: implemented
Prediction target: Residual and saturated volumetric water content and the alpha and n shape parameters of the van Genuchten model with m equal to 1.
Models: \(h(\theta)\) — van Genuchten moisture-retention model with m = 1
Inputs¶
| Name | Type | Unit | Domain | Description |
|---|---|---|---|---|
particle_2000_1000 | number | % | 0 <= value <= 4.50 | Particle content from 2000 to 1000 micrometres. |
particle_1000_500 | number | % | 0 <= value <= 9.30 | Particle content from 1000 to 500 micrometres. |
particle_500_200 | number | % | 0.10 <= value <= 85.70 | Particle content from 500 to 200 micrometres. |
particle_200_100 | number | % | 0.10 <= value <= 68.90 | Particle content from 200 to 100 micrometres. |
particle_100_50 | number | % | 0.70 <= value <= 51.00 | Particle content from 100 to 50 micrometres. |
particle_50_20 | number | % | 0 <= value <= 62.80 | Particle content from 50 to 20 micrometres. |
particle_20_10 | number | % | 0 <= value <= 19.00 | Particle content from 20 to 10 micrometres. |
particle_10_2 | number | % | 0 <= value <= 23.33 | Particle content from 10 to 2 micrometres. |
clay | number | % | 0 <= value <= 54.46 | Particle content below 2 micrometres. |
geometric_mean_particle_size | number | cm | value > 0 | Geometrical mean particle size calculated using the method cited by the paper. |
geometric_standard_deviation | number | dimensionless | value > 0 | Geometrical standard deviation of particle size calculated using the method cited by the paper. |
carbon | number | % | 0.01 <= value <= 6.60 | Carbon content determined by the Walkley-Black method. |
bulk_density | number | g/cm^3 | 1.040 <= value <= 1.730 | Dry bulk density measured after drying undisturbed 100-cm^3 cores for 24 hours at 105 degrees Celsius. |
Outputs¶
| Name | Unit | Domain | Description |
|---|---|---|---|
theta_r | cm^3/cm^3 | 0 <= value <= 1 | Residual volumetric soil water content. |
theta_s | cm^3/cm^3 | 0 <= value <= 1 | Saturated volumetric soil water content. |
alpha | cm^-1 | value > 0 | Shape parameter of the van Genuchten moisture-retention model. |
n | dimensionless | value > 0 | Shape parameter of the van Genuchten moisture-retention model. |
Note
Table 8 reports transformed regressions in original particle-size variables for theta_r, log(alpha), and log(n).
Note
Detailed particle-size information did not substantially improve theta_s; this function therefore retains the broad-texture theta_s regression.
Warning
The detailed log(alpha) formula restores the carbon and bulk-density terms shown in Table 7 but omitted from the supplied Table 8 transcription.
Warning
The bulk-density maximum is reviewed as 1.730 g/cm^3 because the supplied transcription's 1.230 value is inconsistent with the reported mean.