% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/diagnostics-properties-wrb.R
\name{andic_properties}
\alias{andic_properties}
\title{Andic properties (WRB 2022)}
\usage{
andic_properties(
  pedon,
  min_alfe = 2,
  max_bd = 0.9,
  min_p_retention = 70,
  min_oc_proxy = 4,
  max_bd_proxy = 0.9
)
}
\arguments{
\item{pedon}{A \code{\link{PedonRecord}}.}

\item{min_alfe}{Minimum (Al_ox + 0.5*Fe_ox) percent for the Al-Fe
path (default 2.0).}

\item{max_bd}{Maximum bulk density g/cm^3 for the Al-Fe path
(default 0.9).}

\item{min_p_retention}{Minimum phosphate retention \% for the P
path (default 70).}

\item{min_oc_proxy}{Minimum SOC \% for the v0.9.80 OC+BD proxy
path (default 4.0). Only consulted when the proxy is
enabled via \code{options(soilKey.andic_oc_bd_proxy = TRUE)}.}

\item{max_bd_proxy}{Maximum bulk density g/cm^3 for the v0.9.80
OC+BD proxy path (default 0.9). Only consulted when the
proxy is enabled.}
}
\value{
A \code{\link{DiagnosticResult}}.
}
\description{
Tests for the andic property complex -- volcanic-ash-derived
allophanic / imogolitic / Al-humus material. Diagnostic of
Andosols. Two alternative qualifying paths per WRB 2022 Ch 3.2:
\enumerate{
  \item \strong{Al-Fe oxalate + low BD}:
        (Al_ox + 0.5*Fe_ox) >= \code{min_alfe} (default 2.0\%) AND
        bulk_density <= \code{max_bd} (default 0.9 g/cm^3) on the
        same layer.
  \item \strong{Phosphate retention}: phosphate_retention_pct
        >= \code{min_p_retention} (default 70\%).
}
Either path qualifies. The volcanic-glass criterion is the
separate \code{\link{vitric_properties}} diagnostic; Andosols key
on (andic OR vitric) at the RSG-gate level (\code{\link{andosol}}).
}
\section{v0.9.80 OC + BD proxy (opt-in)}{

Field-described volcanic-ash soils (e.g.\ AfSP, KSSL/NASIS, SOTER)
routinely lack oxalate Al/Fe and phosphate retention measurements,
so the canonical paths return \code{NA} and Andosols cascade to
other RSGs. The genetic signature is still detectable from coarser
data: very high SOC (>= 4-5\%) plus low bulk density
(<= 0.9 g/cm^3) typical of allophanic / Al-humus complexation.

With \code{options(soilKey.andic_oc_bd_proxy = TRUE)} the function
adds a third path that fires when both canonical paths fail and the
surface horizon shows \code{oc_pct >= min_oc_proxy} AND
\code{bulk_density_g_cm3 <= max_bd_proxy} (or OC alone >= 5\% when
BD is missing). Default is \code{FALSE} (canonical behaviour
preserved).
}

\section{v0.9.85 proxy contiguous-layer extension (opt-in)}{

When \code{options(soilKey.andic_oc_bd_proxy_extend = TRUE)}
(only meaningful with \code{soilKey.andic_oc_bd_proxy = TRUE}),
iteratively extend the proxy layers to include contiguous deeper
layers whose \code{oc_pct >= min_oc_proxy / 2} AND whose
\code{bulk_density_g_cm3} is missing OR
\code{<= max_bd_proxy + 0.15}. The extension stops at the first
horizon failing either constraint, so a ferralic / argic subsoil
cannot accidentally inflate the andic thickness. Default is
\code{FALSE} -- canonical proxy behaviour preserved.
}

\references{
IUSS Working Group WRB (2022), Chapter 3, Andic
  properties.
}
