Varallyai et al. (1982), water-retention parameter regressions for Hungarian soils.¶
Source¶
Varallyai, D., Raikai, K., Mironenko, Ye. V., Pachepskiy, Ya. A., & Scherbakov, R. A. (1982). A mathematical description of basic water-physical soil characteristics. Pochvovedenie, (4), 77-89.
Scope¶
Territory: Hungary, mainly the Hungarian Plain
Dataset: Undisturbed samples from 559 genetic horizons in 160 soil profiles; the meadow-series regressions used 68 samples and the chernozem comparison used 108 samples.
Functions¶
calc_ptf_varallyai1982_meadow¶
Estimate equation (9) water-retention parameters for meadow-series soils.
Status: implemented
Prediction target: Parameters of the equation (9) water-retention model.
Models: \(h(\theta)\) — theta = theta_0 / (1 + (psi / psi_*)^m)
Inputs¶
| Name | Type | Unit | Domain | Description |
|---|---|---|---|---|
bulk_density | number | g/cm^3 | value > 0 | Undisturbed-soil bulk density. |
fine_sand_fraction | number | fraction | 0 <= value <= 1 | Mass fraction in the 0.25-0.05 mm particle-size class. |
fine_fraction | number | fraction | 0 <= value <= 1 | Fine-particle mass fraction reported as particles smaller than 0.002 mm. |
Outputs¶
| Name | Unit | Domain | Description |
|---|---|---|---|
theta_0 | vol.% | — | Upper-asymptote water content parameter of equation (9). |
m | dimensionless | — | Shape parameter of equation (9). |
pf_star | dimensionless | — | Base-10 logarithm of the equation (9) suction-scale parameter psi_*, with suction expressed in centimetres of water. |
Note
Equation (14) was fitted to 68 meadow-series soil samples.
Note
S and C are fractions of one, while bulk density is in g/cm^3.
Note
The source reports 95% relative errors of 14% for theta_0, 34% for m, and 25% for pF_*.
Warning
Use is described as approximate by the source.
Warning
The source does not report exact calibration ranges; avoid extrapolation beyond comparable Hungarian meadow-series soils.
calc_ptf_varallyai1982_chernozem_a¶
Estimate equation (9) water-retention parameters for chernozem A horizons.
Status: implemented
Prediction target: Parameters of the equation (9) water-retention model for chernozem A horizons.
Models: \(h(\theta)\) — theta = theta_0 / (1 + (psi / psi_*)^m)
Inputs¶
| Name | Type | Unit | Domain | Description |
|---|---|---|---|---|
bulk_density | number | g/cm^3 | value > 0 | Undisturbed-soil bulk density. |
fine_fraction | number | fraction | 0 <= value <= 1 | Fine-particle mass fraction reported as particles smaller than 0.002 mm. |
Outputs¶
| Name | Unit | Domain | Description |
|---|---|---|---|
theta_0 | vol.% | — | Upper-asymptote water content parameter of equation (9). |
m | dimensionless | — | Shape parameter of equation (9). |
pf_star | dimensionless | — | Base-10 logarithm of the equation (9) suction-scale parameter psi_*, with suction expressed in centimetres of water. |
Note
Equation (15) applies to chernozem A horizons.
Note
The source reports 95% relative errors of 10% for theta_0, 29% for m, and 18% for pF_*.
Warning
Use is described as approximate by the source.
Warning
The source does not report exact calibration ranges; avoid extrapolation beyond comparable Hungarian chernozem A horizons.
calc_ptf_varallyai1982_chernozem_b¶
Estimate equation (9) water-retention parameters for chernozem B horizons.
Status: implemented
Prediction target: Parameters of the equation (9) water-retention model for chernozem B horizons.
Models: \(h(\theta)\) — theta = theta_0 / (1 + (psi / psi_*)^m)
Inputs¶
| Name | Type | Unit | Domain | Description |
|---|---|---|---|---|
bulk_density | number | g/cm^3 | value > 0 | Undisturbed-soil bulk density. |
fine_fraction | number | fraction | 0 <= value <= 1 | Fine-particle mass fraction reported as particles smaller than 0.002 mm. |
Outputs¶
| Name | Unit | Domain | Description |
|---|---|---|---|
theta_0 | vol.% | — | Upper-asymptote water content parameter of equation (9). |
m | dimensionless | — | Shape parameter of equation (9). |
pf_star | dimensionless | — | Base-10 logarithm of the equation (9) suction-scale parameter psi_*, with suction expressed in centimetres of water. |
Note
Equation (16) applies to chernozem B horizons.
Note
The source reports 95% relative errors of 11% for theta_0, 34% for m, and 18% for pF_*.
Warning
Use is described as approximate by the source.
Warning
The source does not report exact calibration ranges; avoid extrapolation beyond comparable Hungarian chernozem B horizons.
calc_ptf_varallyai1982_chernozem_c¶
Estimate equation (9) water-retention parameters for chernozem C horizons.
Status: implemented
Prediction target: Parameters of the equation (9) water-retention model for chernozem C horizons.
Models: \(h(\theta)\) — theta = theta_0 / (1 + (psi / psi_*)^m)
Inputs¶
| Name | Type | Unit | Domain | Description |
|---|---|---|---|---|
bulk_density | number | g/cm^3 | value > 0 | Undisturbed-soil bulk density. |
fine_fraction | number | fraction | 0 <= value <= 1 | Fine-particle mass fraction reported as particles smaller than 0.002 mm. |
Outputs¶
| Name | Unit | Domain | Description |
|---|---|---|---|
theta_0 | vol.% | — | Upper-asymptote water content parameter of equation (9). |
m | dimensionless | — | Shape parameter of equation (9). |
pf_star | dimensionless | — | Base-10 logarithm of the equation (9) suction-scale parameter psi_*, with suction expressed in centimetres of water. |
Note
Equation (17) applies to chernozem C horizons.
Note
The source reports 95% relative errors of 7% for theta_0, 22% for m, and 11% for pF_*.
Warning
Use is described as approximate by the source.
Warning
The source does not report exact calibration ranges; avoid extrapolation beyond comparable Hungarian chernozem C horizons.