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Dijkerman (1988), texture-based gravimetric water retention for Sierra Leone soils.

Source

Dijkerman, J. C. (1988). An Ustult-Aquult-Tropept catena in Sierra Leone, West Africa, II. Land qualities and land evaluation. Geoderma, 42, 29-49.

DOI: 10.1016/0016-7061(88)90021-3

Scope

Territory: Sierra Leone, West Africa

Dataset: 166 soil samples from 42 soil profiles reported by Odell et al. (1974). Samples with organic carbon greater than 4% were excluded from the regressions.

Functions

calc_ptf_dijkerman1988

Estimate gravimetric water contents at 15 bar and one-third bar from texture.

Status: ready-for-implementation

Prediction target: Gravimetric water contents at 15 bar and one-third bar.

Inputs

Name Type Unit Domain Description
clay number % 1.3 <= clay <= 66.6 Clay content by mass. The supplied research notes report this observed calibration range from a reconstruction of Odell et al. (1974), Appendix B.
sand number % 0.5 <= sand <= 96.4 Sand content by mass. The supplied research notes report this observed calibration range from a reconstruction of Odell et al. (1974), Appendix B.

Outputs

Name Unit Domain Description
water_content_15_bar % — Gravimetric moisture content at 15 bar, in weight percentage.
water_content_one_third_bar % — Gravimetric moisture content at one-third bar, in weight percentage.

Note

Sand, silt, and clay percentages must sum to 100; sand plus clay must not exceed 100.

Note

The regression dataset excludes samples containing more than 4% organic carbon.

Note

These are two point predictions, not a continuous retention curve.

Warning

The paper describes these relationships as rough guides.

Warning

One-third-bar moisture content may underestimate field capacity and available moisture in these soils.

Warning

The observed marginal calibration ranges do not establish validity for every joint texture combination.

calc_ptf_dijkerman1988_available_water

Estimate the gravimetric available moisture between one-third bar and 15 bar.

Status: ready-for-implementation

Prediction target: Gravimetric available moisture between one-third bar and 15 bar.

Inputs

Name Type Unit Domain Description
clay number % 1.3 <= clay <= 66.6 Clay content by mass. The supplied research notes report this observed calibration range from a reconstruction of Odell et al. (1974), Appendix B.
silt number % 0 <= silt <= 100; 0.5 <= 100 - clay - silt <= 96.4 Silt content by mass; sand, silt, and clay sum to 100%. No separate observed silt calibration range is supplied.

Outputs

Name Unit Domain Description
available_water % — Difference in gravimetric moisture contents, in weight percentage points.

Note

This estimates a gravimetric difference, not profile water storage or a volumetric fraction.

Note

Use soil material with organic carbon at most 4% and physically consistent texture percentages.

Warning

Available moisture estimated using one-third bar may be somewhat low according to the paper.