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Gibbsic qualifier (gi): high gibbsite (>= 25%) in fine earth

Source: R/qualifiers-wrb2022-v0963.R
qual_gibbsic.Rd

WRB 2022 Ch 5 (Plinthosols / Ferralsols): "Containing layers with >= 25% gibbsite by mass averaged over a depth of 100 cm".

Usage

qual_gibbsic(pedon)

Arguments

pedon

A PedonRecord.

Details

soilKey schema does not currently carry direct gibbsite percent. The closest proxy is al_ox_pct (oxalate-extractable Al, %), but gibbsite is poorly extracted by oxalate. The sulfuric attack al2o3_sulfuric_pct captures crystalline Al-oxides (gibbsite + boehmite + diaspore + Al-substitution in goethite). This implementation uses Al2O3 by sulfuric attack >= 25% as a proxy (slight over-estimate, since not all crystalline Al is gibbsite).