% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/diagnostics-horizons-wrb.R
\name{natric_horizon}
\alias{natric_horizon}
\title{Natric horizon (WRB 2022)}
\usage{
natric_horizon(pedon, min_esp = 15, min_pH_h2o = 7)
}
\arguments{
\item{pedon}{A \code{\link{PedonRecord}}.}

\item{min_esp}{Minimum ESP \% (default 15).}

\item{min_pH_h2o}{Minimum pH(H2O) for the ESP-only path
(default 7.0; alkaline gate to exclude false-positive
acidic Bt horizons).}
}
\value{
A \code{\link{DiagnosticResult}}.
}
\description{
Tests for the natric horizon: an argic horizon with diagnostic
sodium accumulation (ESP >= 15\%) within at least one argic layer.
Diagnostic of Solonetz.
}
\section{v0.9.76 designation + ESP-only inference (opt-in)}{

Field-described Solonetz profiles in NCSS / KSSL data routinely
reach the natric ESP threshold (computed from
\code{na_cmol / cec_cmol}) without satisfying the strict
\code{argic()} clay-increase test, because surveyors record
\code{Btk}-suffix designations (carbonates dominate the horizon
designation choice) rather than \code{Btn}/\code{Bn} or
\code{clay_pct} is missing.

With \code{options(soilKey.natric_designation_inference = TRUE)} the
function accepts a layer as natric when the canonical argic test
returns NA or FALSE AND \emph{either}:
\enumerate{
  \item the designation matches \code{[A-Z][a-z0-9]*n} (an \code{n}
        master-letter modifier in the horizon name -- e.g.\
        \code{Btn}, \code{Btnz}, \code{Bn}, the curator's direct
        assertion that natric features are present), OR
  \item ESP >= \code{min_esp} on a B-prefixed subsoil layer
        (\code{top_cm > 20}) AND the layer's pH(H2O) >= 7
        (alkaline -- typical of true natric, excludes acidic Bt
        horizons that happen to read high Na from sea-spray).
}

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

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