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Dharumarajan et al. (2019) hydraulic PTFs for the Karnataka Plateau.

Source

Dharumarajan, S., Hegde, R., Lalitha, M., Kalaiselvi, B., & Singh, S. K. (2019). Pedotransfer functions for predicting soil hydraulic properties in semi-arid regions of Karnataka Plateau, India. Current Science, 116(7), 1237-1246. https://doi.org/10.18520/cs/v116/i7/1237-1246

DOI: 10.18520/cs/v116/i7/1237-1246

Scope

Territory: Karnataka Plateau, India

Dataset: Field capacity and permanent wilting point were modeled from 512 soil samples in the Northern Karnataka Plateau and 228 samples in the Southern Karnataka Plateau; infiltration was modeled from 100 Karnataka soil observations.

Functions

calc_ptf_dharumarajan2019_nkp

Estimate field capacity and wilting point for Northern Karnataka soils.

Status: implemented

Prediction target: Water content at field capacity and permanent wilting point from clay, sand, and cation exchange capacity.

Models: \(h(\theta)\) — Point water-retention estimates from multiple linear regression

Inputs

Name Type Unit Domain Description
clay number % Northern study range: 1.2 <= value <= 80.8 Clay content.
sand number % Northern study range: 2.7 <= value <= 94.0 Sand content.
cation_exchange_capacity number C mol p+/kg Northern study range: 1.7 <= value <= 80.9 Cation exchange capacity.

Outputs

Name Unit Domain Description
field_capacity % — Soil water content at -33 kPa matric potential.
permanent_wilting_point % — Soil water content at -1500 kPa matric potential.

Note

The model was fitted to 512 soil-layer observations.

Note

Reported cross-validation RMSE values are 5.25% for FC and 3.71% for PWP.

Warning

The paper does not state whether its water-content percentages are gravimetric or volumetric.

Warning

The source gives inconsistent profile counts and district lists for the Northern dataset; see the scientific notes.

calc_ptf_dharumarajan2019_nkp_clay

Estimate Northern Karnataka field capacity and wilting point from clay.

Status: implemented

Prediction target: Water content at field capacity and permanent wilting point from clay content alone.

Models: \(h(\theta)\) — Point water-retention estimates from simple linear regression

Inputs

Name Type Unit Domain Description
clay number % Northern study range: 1.2 <= value <= 80.8 Clay content.

Outputs

Name Unit Domain Description
field_capacity % — Soil water content at -33 kPa matric potential.
permanent_wilting_point % — Soil water content at -1500 kPa matric potential.

Note

The paper recommends this model when clay content is the only available predictor.

Note

Reported cross-validation RMSE values are 7.05% for FC and 4.74% for PWP.

Warning

The paper does not state whether its water-content percentages are gravimetric or volumetric.

Warning

The source gives inconsistent profile counts and district lists for the Northern dataset; see the scientific notes.

calc_ptf_dharumarajan2019_skp

Estimate field capacity and wilting point for Southern Karnataka soils.

Status: implemented

Prediction target: Water content at field capacity and permanent wilting point from clay, sand, and cation exchange capacity.

Models: \(h(\theta)\) — Point water-retention estimates from multiple linear regression

Inputs

Name Type Unit Domain Description
clay number % Southern study range: 5.8 <= value <= 67.8 Clay content.
sand number % Southern study range: 4.4 <= value <= 92.3 Sand content.
cation_exchange_capacity number C mol p+/kg Southern study range: 1.2 <= value <= 52.6 Cation exchange capacity.

Outputs

Name Unit Domain Description
field_capacity % — Soil water content at -33 kPa matric potential.
permanent_wilting_point % — Soil water content at -1500 kPa matric potential.

Note

The model was fitted to 228 soil samples from 43 profiles.

Note

Reported cross-validation RMSE values are 3.05% for FC and 2.17% for PWP.

Warning

The paper does not state whether its water-content percentages are gravimetric or volumetric.

calc_ptf_dharumarajan2019_skp_clay

Estimate Southern Karnataka field capacity and wilting point from clay.

Status: implemented

Prediction target: Water content at field capacity and permanent wilting point from clay content alone.

Models: \(h(\theta)\) — Point water-retention estimates from simple linear regression

Inputs

Name Type Unit Domain Description
clay number % Southern study range: 5.8 <= value <= 67.8 Clay content.

Outputs

Name Unit Domain Description
field_capacity % — Soil water content at -33 kPa matric potential.
permanent_wilting_point % — Soil water content at -1500 kPa matric potential.

Note

The paper recommends this model when clay content is the only available predictor.

Note

Reported cross-validation RMSE values are 5.39% for FC and 3.13% for PWP.

Warning

The paper does not state whether its water-content percentages are gravimetric or volumetric.

calc_ptf_dharumarajan2019_infiltration

Estimate infiltration rate for Karnataka soils from texture fractions.

Status: implemented

Prediction target: Infiltration rate from sand, silt, and clay contents.

Models: \(k(h)\) — Multiple linear regression for infiltration rate

Inputs

Name Type Unit Domain Description
sand number % — Sand content in the Karnataka infiltration dataset.
silt number % — Silt content in the Karnataka infiltration dataset.
clay number % — Clay content in the Karnataka infiltration dataset.

Outputs

Name Unit Domain Description
infiltration_rate mm/h Observed study range: 2.3 <= value <= 35 Soil infiltration rate measured with a double-ring infiltrometer.

Note

The model was fitted to 100 Karnataka soil observations.

Note

The reported model R-squared is 41%, and the reported RMSE is 6.71%.

Warning

Predictor calibration ranges are not reported for the 100-observation dataset.