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

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

\item{min_plinthite_pct}{Minimum volume \% plinthite (default 15).}
}
\value{
A \code{\link{DiagnosticResult}}.
}
\description{
Tests whether any horizon meets the plinthic horizon criteria.
Plinthite is Fe-rich material that hardens irreversibly on repeated
wetting and drying; the plinthic horizon is the diagnostic of
Plinthosols.
}
\details{
Sub-tests:
\itemize{
  \item \code{test_plinthite_concentration} -- plinthite
        volume \% >= 15
  \item \code{test_minimum_thickness} -- thickness >= 15 cm
}

v0.2 limitations: WRB 2022 also accepts profiles with >= 40\% red
Fe-rich mottles as alternative criterion -- not yet wired. The
"irreversibly hardens" criterion is conceptual and requires field
observation; v0.2 takes \code{plinthite_pct} as already representing
true plinthite (as opposed to soft mottles).
}
\section{v0.9.72 designation morphological inference (opt-in)}{

Field-described Brazilian Plintossolos profiles (e.g.\ the Embrapa
Redape curated dataset) routinely encode plinthite via the
designation suffix \code{f} in the master letter sequence (e.g.\
\code{Btf}, \code{2Btf}, \code{Cf}) -- the curator's direct
assertion that plinthite is present -- without recording
\code{plinthite_pct} as a numeric volume percent.

With \code{options(soilKey.plinthic_designation_inference = TRUE)} the
function accepts a layer as plinthic when:
\enumerate{
  \item the canonical \code{plinthite_pct} test is \code{NA} for
        that layer, AND
  \item the designation matches \code{[A-Z]+[A-Za-z]*f[0-9]?}
        (a \code{f} master-letter modifier in any sub-position).
}

Default is \code{FALSE} (canonical behaviour preserved).
}

\references{
IUSS Working Group WRB (2022), Chapter 3, Plinthic horizon.
}
