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Quartzipsamment helper (Quartzipsamments: >= 95% resistant minerals)

Source: R/diagnostics-entisols-usda.R
quartzipsamment_qualifying_usda.Rd

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.

Usage

quartzipsamment_qualifying_usda(pedon)

Arguments

pedon

A PedonRecord.

Details

v0.9.31 broadens the proxy from "clay <= 5 <= 5 were caught) to:

  • clay_pct <= 10 (loamy sands and finer sands all qualify – the 5

  • sand_pct >= 80 (sand-dominated texture – a NEW requirement, since clay alone is not sufficient);

  • coarse_fragments_pct <= 15 (some coarse fragments tolerated; 5

  • at least 50 (preserved from v0.8).

This still excludes Loamy Psamments and Sandy-Loamy Psamments (Udipsamments / Ustipsamments fallthroughs) by requiring sand >= 80 near-pure-sand texture.