<ptfkit/dijkerman1988.h>¶
#include <ptfkit/dijkerman1988.h>
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.
dijkerman1988_water_content¶
typedef struct {
double water_content_15_bar;
double water_content_one_third_bar;
} dijkerman1988_water_content;
| Field | 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. (%) |
Functions¶
calc_ptf_dijkerman1988¶
Estimate gravimetric water contents at 15 bar and one-third bar from texture.
static inline dijkerman1988_water_content calc_ptf_dijkerman1988(double clay, double sand);
Parameters¶
| Name | Direction | Description |
|---|---|---|
clay | in | Clay content by mass. The supplied research notes report this observed calibration range from a reconstruction of Odell et al. (1974), Appendix B. (%) |
sand | in | Sand content by mass. The supplied research notes report this observed calibration range from a reconstruction of Odell et al. (1974), Appendix B. (%) |
Returns¶
A dijkerman1988_water_content value.
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.
static inline double calc_ptf_dijkerman1988_available_water(double clay, double silt);
Parameters¶
| Name | Direction | Description |
|---|---|---|
clay | in | Clay content by mass. The supplied research notes report this observed calibration range from a reconstruction of Odell et al. (1974), Appendix B. (%) |
silt | in | Silt content by mass; sand, silt, and clay sum to 100%. No separate observed silt calibration range is supplied. (%) |
Returns¶
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.