<ptfkit/mayr1999.h>¶
#include <ptfkit/mayr1999.h>
Mayr and Jarvis (1999) modified Brooks-Corey water-retention parameter PTFs.
Source¶
Mayr, T., & Jarvis, N. J. (1999). Pedotransfer functions to estimate soil water retention parameters for a modified Brooks-Corey type model. Geoderma, 91(1-2), 1-9.
DOI: 10.1016/S0016-7061(98)00129-3
Scope¶
Territory: England and Wales
Dataset: Soil Survey and Land Research Centre soil physical properties database; regressions used 286 soil horizons retained from a 306-horizon subset after excluding fits with RMSE greater than 0.05 m^3/m^3, and validation used 1678 independent soil horizons.
mayr1999_ptf_result¶
typedef struct {
double a_hc;
double b_hc;
double theta_s;
} mayr1999_ptf_result;
| Field | Description |
|---|---|
a_hc | Hutson-Cass fitting parameter with pressure-head dimensions. (cm H2O) |
b_hc | Hutson-Cass fitting parameter controlling retention-curve shape. (dimensionless) |
theta_s | Volumetric soil water content at saturation. (m^3/m^3) |
Functions¶
calc_ptf_mayr1999¶
Estimate modified Brooks-Corey a, b, and saturated water content from texture, bulk density, and organic carbon.
static inline mayr1999_ptf_result calc_ptf_mayr1999(double sand, double silt, double clay, double bulk_density, double organic_carbon);
Parameters¶
| Name | Direction | Description |
|---|---|---|
sand | in | Sand content for particles 0.063-2.0 mm. (%) |
silt | in | Silt content for particles 0.002-0.063 mm. (%) |
clay | in | Clay content for particles 0-0.002 mm. (%) |
bulk_density | in | Dry bulk density; the paper excludes application below 0.9 g/cm^3. (g/cm^3) |
organic_carbon | in | Organic carbon content; the paper excludes application above 5%. (%) |
Returns¶
A mayr1999_ptf_result value.
Note
The particle-size inputs use the UK size boundaries stated by the paper; sand, silt, and clay are percentages.
Note
The source reports r^2 values of 0.34 for log(a), 0.74 for log(1/b), and 0.84 for theta_s.
Note
Human review resolved the source's unspecified log base as base 10; the implementation therefore interprets log(a) and log(1/b) as log10 values.
Warning
Do not apply the functions to organic soils with organic carbon above 5% or soils with dry bulk density below 0.9 g/cm^3.
Warning
Treat application outside the calibration particle-size distribution with great care; the paper provides that distribution only graphically.