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Anhydrous conditions (USDA Soil Taxonomy, 13th edition)

Source: R/diagnostics-conditions-usda.R
anhydrous_conditions_usda.Rd

"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.

Usage

anhydrous_conditions_usda(pedon)

Arguments

pedon

A PedonRecord.

Value

A DiagnosticResult.

Details

Required characteristics:

  • Mean annual soil temperature <= 0 C; AND

  • Layer 10-70 cm with soil temperature < 5 C throughout the year; AND

  • No ice-impregnated permafrost in that layer; AND

  • One of:

    • Dry (>= 1500 kPa) in 1/2+ of soil for 1/2+ of time above 0 C; OR

    • Rupture-resistance class loose to slightly hard throughout when temp <= 0 C (except where pedogenically cemented).

Implementation (v0.8.x): Uses 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.