% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/diagnostics-conditions-usda.R
\name{anhydrous_conditions_usda}
\alias{anhydrous_conditions_usda}
\title{Anhydrous conditions (USDA Soil Taxonomy, 13th edition)}
\usage{
anhydrous_conditions_usda(pedon)
}
\arguments{
\item{pedon}{A \code{\link{PedonRecord}}.}
}
\value{
A \code{\link{DiagnosticResult}}.
}
\description{
"Anhydrous conditions refer to the moisture condition of soils in
very cold deserts and other areas with permafrost (often dry
permafrost). These soils typically have low precipitation
(usually less than 50 mm water equivalent per year) and a moisture
content of less than 3 percent by weight."  -- KST 13ed, Ch 3,
p 33.
}
\details{
Required characteristics:
\itemize{
  \item Mean annual soil temperature <= 0 C; AND
  \item Layer 10-70 cm with soil temperature < 5 C throughout the year; AND
  \item No ice-impregnated permafrost in that layer; AND
  \item One of:
    \itemize{
      \item Dry (>= 1500 kPa) in 1/2+ of soil for 1/2+ of time
            above 0 C; OR
      \item Rupture-resistance class loose to slightly hard
            throughout when temp <= 0 C (except where pedogenically
            cemented).
    }
}

Implementation (v0.8.x): Uses \code{permafrost_temp_C} from schema
to flag layers below freezing; checks rupture_resistance for
"loose" / "soft" / "slightly hard" in the 10-70 cm layer.
Precipitation criterion is deferred to v0.9 (climatic data).
}
\references{
Soil Survey Staff (2022), KST 13ed, Ch. 3, p 33.
}
