% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/diagnostics-horizons-wrb.R
\name{cambic}
\alias{cambic}
\title{Cambic horizon (WRB 2022)}
\usage{
cambic(pedon, min_thickness = 15, min_top_cm = 5, engine = NULL)
}
\arguments{
\item{pedon}{A \code{\link{PedonRecord}}.}

\item{min_thickness}{Minimum thickness in cm (default 15).}

\item{min_top_cm}{Minimum top depth (cm) for a horizon to be
considered cambic-eligible (default 5). Anchors the
candidate set to subsurface layers.}

\item{engine}{v0.9.63+. One of \code{"soilkey"} (hand-coded path,
default for back-compat) or \code{"aqp"} (canonical NRCS
dispatch via \code{aqp::getCambicBounds}). When \code{NULL}
(the new default) the function reads
\code{getOption("soilKey.diagnostic_engine", "soilkey")},
so a global \code{options(soilKey.diagnostic_engine = "aqp")}
flips every \code{cambic()} call without modifying call
sites. The aqp engine fired 40.6% of BDsolos RJ perfis vs
soilkey 0% in the v0.9.62 A/B benchmark -- and lifted the
v0.9.50 LUCAS WRB benchmark from 0% to 60% (Cambisols recall
100%) when combined with subsoil-fill SoilGrids. See
\code{\link{cambic_aqp}}.}
}
\value{
A \code{\link{DiagnosticResult}}.
}
\description{
Tests whether any horizon meets the cambic horizon criteria. The
cambic horizon is a subsurface horizon with evidence of pedological
alteration that does not meet the criteria for any stronger
diagnostic horizon. It is the diagnostic of Cambisols.
}
\details{
v0.2 implementation tests three conditions:
\itemize{
  \item thickness >= 15 cm (\code{\link{test_minimum_thickness}})
  \item texture sandy loam or finer (\code{\link{test_texture_argic}})
  \item NOT \code{\link{argic}} AND NOT \code{\link{ferralic}}
}

v0.2 limitations: WRB 2022 also excludes profiles with spodic,
calcic, gypsic, plinthic, vertic, and several other diagnostic
horizons. Those exclusions, plus the WRB criteria of "evidence of
alteration" (color/structure differences from parent material,
carbonate removal), are scheduled for v0.3.
}
\references{
IUSS Working Group WRB (2022), Chapter 3, Cambic horizon.
}
