Thapto-Humic Subgroup helper — thapto_humic

Pass when a buried layer meets criteria for histic, mollic, umbric, or melanic epipedon within 200 cm of the soil surface, OR buried O and dark-colored A horizons (V <= 3 moist, combined thickness >= 20 cm, OC >= 1 percent Holocene-age) within 200 cm (KST 13ed, p 189-191).

Usage

thapto_humic_usda(
  pedon,
  max_top_cm = 200,
  min_thickness_cm = 20,
  min_oc_pct = 1
)

Arguments

pedon: A PedonRecord.
max_top_cm: Default 200.
min_thickness_cm: Default 20.
min_oc_pct: Default 1.0.

Value

A DiagnosticResult.

Details

Implementation detects buried horizons via designation containing 'b' (KST notation for buried) AND dark color (V <= 3) within 200 cm.

References

Soil Survey Staff (2022), KST 13ed, Ch. 9 various.