Leptic features (WRB 2022) — leptic

Tests whether continuous rock or rock-like material occurs within max_depth cm of the surface. Two alternative paths qualify per WRB 2022:

Designation: a layer at depth <= max_depth with designation matching "^R" or "^Cr" (continuous rock or weathered rock-like substrate).
Coarse fragments: a layer at depth <= max_depth with coarse_fragments_pct >= min_coarse_pct (default 90% by volume), interpreted as rock-dominated even when not R / Cr-designated.

Either path qualifies.

Usage

leptic_features(pedon, max_depth = 25, min_coarse_pct = NULL, engine = NULL)

pedon: A PedonRecord.
max_depth: Maximum depth (cm) at which continuous rock or rock-dominated material must appear (default 25).
min_coarse_pct: Minimum coarse-fragment percent for the coarse-fragments path (default 90 in soilkey engine, 50 in aqp engine; NULL picks a default per engine).
engine: One of "soilkey" (default; strict 90\ cfvo threshold) or "aqp" (LUCAS-friendly relaxed 50\ requiring positive evidence of rock contact – v0.9.66 tightening). The thin-topsoil path fires only when a horizon ending within max_depth also satisfies at least one of: (a) designation contains "R" (e.g.\ AR, BR, Cr, R, Rk), (b) coarse_fragments_pct >= 30 (gravelly), or (c) a deeper horizon is R/Cr-designated. Users with a strong external prior (e.g.\ a parent-material survey that documents rock < 25 cm but did not record it in the horizon table) can opt back into the original v0.9.65 loose behaviour with options(soilKey.leptic_assume_rock_below = TRUE). NULL (the default) reads getOption("soilKey.diagnostic_engine").

IUSS Working Group WRB (2022), Chapter 5, Leptosols.