Tests whether any horizon shows vertic properties – shrink-swell clay behaviour evidenced by slickensides, wedge-shaped peds, and deep cracks. Diagnostic for Vertisols.
Usage
vertic_properties(
pedon,
min_clay = 30,
min_thickness = 25,
slickenside_levels = c("common", "many", "continuous")
)Arguments
- pedon
A
PedonRecord.- min_clay
Minimum clay percent (default 30, per WRB 2022).
- min_thickness
Minimum thickness (cm) of the vertic layer (default 25 per WRB 2022 Ch 3.2.x).
- slickenside_levels
Vector of
slickensidesvalues accepted as evidence (defaultc("common", "many", "continuous")).
Details
Sub-tests:
test_clay_above– clay >= 30%test_slickensides_present– slickensides at or above the "common" leveltest_minimum_thickness– combined vertic layer thickness >= 25 cm (v0.3.1 added per WRB 2022)
v0.3.1: thickness gate added. Limitations remaining: WRB also accepts deep cracks (>= 1 cm wide extending from the surface to >= 50 cm depth, when soil is dry) and wedge-shaped peds as alternative evidence; this implementation requires clay + slickensides. The "after mixing of upper 18 cm" clause from WRB is still deferred.