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Chernozem RSG gate (strengthened, WRB 2022 Ch 4, p 111)

Source: R/diagnostics-rsg-tier2.R
chernozem_strict.Rd

WRB-canonical: chernic horizon AND, starting \<= 50 cm below the lower limit of the mollic horizon and (if a petrocalcic horizon is present) above it, a layer with protocalcic properties \>= 5 cm thick OR a calcic horizon AND base saturation \>= 50% from the mineral soil surface to the protocalcic / calcic layer throughout. Protocalcic properties are visible secondary carbonates (protocalcic_properties); where BS is not recorded it is read from pH (WRB 2022 Annex 2, Table 9.2).

Usage

chernozem_strict(pedon, min_bs = 50, max_top_cm = 50, strict = NULL)

Arguments

pedon

A PedonRecord.

min_bs

Minimum base saturation % above the carbonate layer (default 50).

max_top_cm

Maximum depth of the carbonate layer below the lower limit of the mollic horizon, cm (default 50).

strict

Logical or NULL. When NULL (default) it resolves via getOption("soilKey.rsg_strict", FALSE). TRUE raises the base-saturation floor to 80%.

Value

A DiagnosticResult recording whether the diagnostic is present, the qualifying layers, and the supporting evidence.

Details

v0.3.4 strengthens the previous v0.2 chernozem (which only required mollic + chernic_color) by adding the protocalcic / calcic gate and the BS \>= 50% requirement.

Note: the v0.2 chernozem() diagnostic remains available as a less-strict variant; chernozem_strict() is what the v0.3.4 key.yaml uses for the CH RSG.

Tier-3 strict mode (v0.9.98)

With strict = TRUE the base-saturation floor above the carbonate-bearing layer is raised from 50% to 80%, in line with the very high base status expected of a textbook Chernozem.