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Andosol RSG gate (WRB 2022 Ch 4, p 104)

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

WRB-canonical: layer(s) with andic OR vitric properties, combined thickness \>= 30 cm within 100 cm starting \<= 25 cm; OR \>= 60% of the entire soil thickness when a limiting layer starts 25-50 cm. Plus: no argic, ferralic, petroplinthic, pisoplinthic, plinthic or spodic horizon \<= 100 cm (unless buried below 50 cm).

Usage

andosol(
  pedon,
  min_thickness = 30,
  max_top_cm = 25,
  buried_below_cm = 50,
  strict = NULL
)

Arguments

pedon

A PedonRecord.

min_thickness

Numeric threshold or option (see Details).

max_top_cm

Numeric threshold or option (see Details).

buried_below_cm

Numeric: layers of the exclusion diagnostics whose top_cm \>= this depth are treated as buried and do NOT exclude the Andosol (default 50, per WRB 2022 Ch 4 p 104).

strict

Logical or NULL. When NULL (default) it resolves via getOption("soilKey.rsg_strict", FALSE). TRUE disables the buried-exclusion tolerance.

Value

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

Details

v0.3.4 enforces (1) andic OR vitric AND (2) combined thickness \>= 30 cm starting in the upper 25 cm AND (3) the negative-list exclusions on argic / ferralic / plinthic / spodic.

v0.9.313 (WRB 2022 Ch 4, p 104, as worded)

The combined thickness is that of every andic or vitric layer within 100 cm of the soil surface (clipped at 100 cm), provided the uppermost starts \<= 25 cm; until v0.9.312 only layers starting \<= 25 cm were added up. Item 1b applies: where a limiting layer starts \> 25 and \<= 50 cm, andic or vitric layers covering \>= 60% of the soil above it qualify. Petroplinthic and pisoplinthic horizons join the exclusions. An argic horizon read from a clay increase alone (no clay films recorded) whose layers all have andic properties does not exclude (Hugo, N4: the clay of andic material does not disperse fully). Layers whose andic or vitric status is not recorded leave the gate undecided (NA) where they could change it.

v0.9.85 buried-exclusion fix

WRB 2022 Ch 4 p 104 specifies the Andosol exclusion list (argic / ferralic / petroplinthic / pisoplinthic / plinthic / spodic) as "<= 100 cm unless buried below 50 cm". The earlier implementation excluded an Andosol whenever any of those diagnostics passed anywhere in the profile, including on layers starting deeper than 50 cm – which mis-fires on AfSP Andosol references like CM W3_0047, where an argic layer at 56-72 cm wrongly excluded the andic surface stack. v0.9.85 restricts the exclusion check to layers starting <= 50 cm: a buried argic / ferralic / plinthic / spodic at deeper levels no longer disqualifies the surface andic stack from Andosol.

Tier-3 strict mode (v0.9.98)

With strict = TRUE the v0.9.85 buried-exclusion tolerance is switched off: any argic / ferralic / plinthic / spodic horizon anywhere in the profile excludes the Andosol, regardless of depth.