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Gleyic properties (WRB 2022)

Source: R/diagnostics-properties-wrb.R
gleyic_properties.Rd

Tests whether the profile shows gleyic properties – evidence of prolonged saturation by groundwater – within the upper 50 cm. Gleyic properties are diagnostic for Gleysols and qualify many other RSGs (Endogleyic, Epigleyic qualifiers).

Usage

gleyic_properties(
  pedon,
  max_top_cm = 50,
  min_redox_pct = 5,
  stagnic_decay_factor = 3
)

Arguments

pedon

A PedonRecord.

max_top_cm

Maximum top depth (cm) of a candidate layer (default 50, per WRB 2022).

min_redox_pct

Minimum redoximorphic_features_pct (default 5).

stagnic_decay_factor

Numeric threshold or option (see Details).

Value

A DiagnosticResult.

Details

Sub-test: test_gleyic_features – requires explicit redoximorphic_features_pct >= 5% within the upper 50 cm.

v0.2 deliberately does NOT use the Munsell-based shortcut (chroma <= 2 + value >= 4) as a primary criterion: that pattern fits albic / bleached horizons of Podzols just as well as truly reduced gleyic horizons. v0.3 will add reductimorphic / oxidimorphic feature discrimination once we model field-described mottle properties. v0.9.72 adds the designation-suffix path (opt-in).

v0.9.72 designation morphological inference (opt-in)

Field-described Brazilian Gleissolos profiles (e.g.\ the Embrapa Redape curated dataset) routinely encode gleyic properties via the designation suffix g (e.g.\ Cg, Cg1, Cgn, Apg) plus low-chroma Munsell colours (chroma \<= 2), without recording redoximorphic_features_pct as a numeric percent. The strict canonical test then returns NA on every horizon and Gleissolos cascade to other Orders.

With options(soilKey.gleyic_designation_inference = TRUE) the function accepts a layer as gleyic when:

  1. the canonical redoximorphic_features_pct test is NA for that layer, AND

  2. the designation matches [A-Z]+g[0-9a-z]? (a horizon name with a g suffix in the master letter sequence, e.g.\ Cg, Bg2, Apg, Cgn), AND

  3. the layer has munsell_chroma_moist <= 2 (low-chroma reduced colour) when Munsell is recorded; if Munsell is missing on the layer the suffix alone is sufficient (designation suffix is the most direct signal of pedologist field judgment).

This is conservative: the suffix g is a master-letter modifier in the FAO/Embrapa horizon nomenclature that explicitly means "gleyic-affected" – the curator already made the call. Default is FALSE (canonical behaviour preserved).

References

IUSS Working Group WRB (2022), Chapter 3, Gleyic properties.