% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/diagnostics-entisols-usda.R
\name{quartzipsamment_qualifying_usda}
\alias{quartzipsamment_qualifying_usda}
\title{Quartzipsamment helper (Quartzipsamments: >= 95\% resistant minerals)}
\usage{
quartzipsamment_qualifying_usda(pedon)
}
\arguments{
\item{pedon}{A \code{\link{PedonRecord}}.}
}
\description{
KST 13ed Ch 8 (p 357) defines Quartzipsamments as Psamments where
"a weighted average of the resistant minerals in the 0.02-2.0 mm
fraction is at least 95 percent". Resistant minerals are dominated
by quartz; the practical proxy is a profile that is uniformly
sandy with very little clay AND minimal coarse fragments AND no
explicit mineralogical evidence of weatherable minerals.
}
\details{
v0.9.31 broadens the proxy from "clay <= 5 % AND coarse_fragments
<= 5 %" (which under-detected; only 0/14 KSSL Quartzipsamments
were caught) to:

\itemize{
  \item \code{clay_pct <= 10} (loamy sands and finer sands all
        qualify -- the 5 % cutoff was too strict);
  \item \code{sand_pct >= 80} (sand-dominated texture -- a NEW
        requirement, since clay alone is not sufficient);
  \item \code{coarse_fragments_pct <= 15} (some coarse fragments
        tolerated; 5 % was overly strict);
  \item at least 50 % of in-range layers must satisfy all three
        (preserved from v0.8).
}

This still excludes Loamy Psamments and Sandy-Loamy Psamments
(Udipsamments / Ustipsamments fallthroughs) by requiring sand >=
80 %; it captures the mineralogical signal indirectly via the
near-pure-sand texture.
}
