% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/diagnostics-epipedons-usda.R
\name{umbric_epipedon_usda}
\alias{umbric_epipedon_usda}
\title{Umbric epipedon (USDA Soil Taxonomy, 13th edition)}
\usage{
umbric_epipedon_usda(pedon, max_bs = 50, min_oc_pct = 0.6)
}
\arguments{
\item{pedon}{A \code{\link{PedonRecord}}.}

\item{max_bs}{Maximum BS (default 50 -- "less than 50 percent").}

\item{min_oc_pct}{Minimum OC (default 0.6).}
}
\value{
A \code{\link{DiagnosticResult}}.
}
\description{
A thick, dark-colored, base-poor (BS < 50 percent) mineral
surface horizon. Differs from mollic in low base saturation;
qualifies the Humults / Humic / Umbric subgroups in many orders.
}
\details{
KST 13ed required characteristics (Ch. 3, pp 18-20):
\itemize{
  \item Color: same as mollic (V<=3 moist, V<=5 dry, chroma<=3);
  \item Base saturation (NH4OAc) < 50 percent in some part;
  \item Organic carbon >= 0.6 percent (or 0.6 absolute > C);
  \item Thickness: same rules as mollic (18 / 25 / 10 cm);
  \item Structure: peds <= 30 cm OR rupture-resistance <= moderately
        hard.
}
}
\references{
Soil Survey Staff (2022), KST 13ed, Ch. 3, pp 18-20.
}
