Soil hydraulic properties by USDA texture class.

Class-average volumetric soil water contents by USDA texture class: total porosity (saturation), field capacity (33 kPa) and permanent wilting point (1500 kPa), each as a volumetric fraction (cubic metre water per cubic metre soil). These are the per-cell soil hydraulic drivers the ICBM soil-carbon moisture modifier consumes (soc_rate_modifier_icbm()'s t_field, t_wilt and porosity); read_soil_hydraulic() joins this table onto the dominant HWSD texture class of each grid cell to emit those columns, which then feed get_soc_climate_drivers(). Every row satisfies porosity > field_capacity > wilting_point with all three in (0, 1).

Usage

soil_hydraulic_by_texture

Format

A tibble with columns:

usda_texture_class

USDA texture class (snake_case): "sand", "loamy_sand", "sandy_loam", "silt_loam", "silt", "loam", "sandy_clay_loam", "silty_clay_loam", "clay_loam", "sandy_clay", "silty_clay" or "clay".

porosity

Total porosity / saturated volumetric water content (fraction).

field_capacity

Volumetric water content at field capacity, 33 kPa (fraction).

wilting_point

Volumetric water content at the permanent wilting point, 1500 kPa (fraction).

Source

Class-average hydraulic properties compiled by texture class in "Average hydraulic properties of ARS soil texture classes" (Schaake, J., draft February 2000; 2128 soil samples), the values used as the default soil-texture lookup in the VIC land-surface model (https://vic.readthedocs.io/en/master/Documentation/soiltext/). The underlying regression relating the water-retention parameters to texture is Cosby, B. J., Hornberger, G. M., Clapp, R. B. & Ginn, T. R. (1984). A statistical exploration of the relationships of soil moisture characteristics to the physical properties of soils. Water Resources Research, 20(6), 682-690. doi:10.1029/WR020i006p00682 .

Examples

soil_hydraulic_by_texture
#> # A tibble: 12 × 4
#>    usda_texture_class porosity field_capacity wilting_point
#>    <chr>                 <dbl>          <dbl>         <dbl>
#>  1 sand                   0.43           0.08          0.03
#>  2 loamy_sand             0.42           0.15          0.06
#>  3 sandy_loam             0.4            0.21          0.09
#>  4 silt_loam              0.46           0.32          0.12
#>  5 silt                   0.52           0.28          0.08
#>  6 loam                   0.43           0.29          0.14
#>  7 sandy_clay_loam        0.39           0.27          0.17
#>  8 silty_clay_loam        0.48           0.36          0.21
#>  9 clay_loam              0.46           0.34          0.21
#> 10 sandy_clay             0.41           0.31          0.23
#> 11 silty_clay             0.49           0.37          0.25
#> 12 clay                   0.47           0.36          0.27