# End-to-end WRB 2022 classification with Ch 6 names

This vignette walks the full WRB 2022 (4th edition) classification flow on the canonical Ferralsol fixture, end to end – from a raw `PedonRecord` to the complete Chapter 6 name with both principal and supplementary qualifiers in the canonical parenthesised form.

The Ferralsol fixture represents a typical Brazilian Latossolo (gneiss-derived, Mata Atlântica). After v0.9.3, `classify_wrb2022()` resolves it to:

    Geric Ferric Rhodic Chromic Ferralsol (Clayic, Humic, Dystric, Ochric, Rubic)

We will inspect each step that produces that name.

# 1. Build the pedon

The canonical fixture exposes a published-quality profile. Use it as the working pedon.

    pr <- make_ferralsol_canonical()
    pr
    #>
    #> ── PedonRecord ──
    #>
    #> Site: id=FR-canonical-01 | (-22.5000, -43.7000) | BR | 2024-03-10 | on gneiss
    #> Horizons (5):
    #> 1) A 0-15 cm clay=50.0 silt=15.0 sand=35.0 CEC=8.0 pH=4.8 OC=2.0
    #> 2) AB 15-35 cm clay=52.0 silt=14.0 sand=34.0 CEC=6.5 pH=4.7 OC=1.2
    #> 3) BA 35-65 cm clay=55.0 silt=10.0 sand=35.0 CEC=5.5 pH=4.7 OC=0.6
    #> 4) Bw1 65-130 cm clay=60.0 silt=8.0 sand=32.0 CEC=5.0 pH=4.8 OC=0.3
    #> 5) Bw2 130-200 cm clay=60.0 silt=8.0 sand=32.0 CEC=4.8 pH=4.9 OC=0.2

A glance at the horizons and chemistry:

    knitr::kable(
      pr$horizons[, .(top_cm, bottom_cm, designation,
                      munsell_hue_moist, munsell_value_moist, munsell_chroma_moist,
                      clay_pct, oc_pct, cec_cmol, bs_pct,
                      ph_h2o, ph_kcl)]
    )

top_cm | bottom_cm | designation | munsell_hue_moist | munsell_value_moist | munsell_chroma_moist | clay_pct | oc_pct | cec_cmol | bs_pct | ph_h2o | ph_kcl
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
0 | 15 | A | 2.5YR | 3 | 4 | 50 | 2.0 | 8.0 | 24 | 4.8 | 4.0
15 | 35 | AB | 2.5YR | 3 | 4 | 52 | 1.2 | 6.5 | 17 | 4.7 | 4.0
35 | 65 | BA | 2.5YR | 3 | 6 | 55 | 0.6 | 5.5 | 14 | 4.7 | 4.0
65 | 130 | Bw1 | 2.5YR | 4 | 6 | 60 | 0.3 | 5.0 | 13 | 4.8 | 4.1
130 | 200 | Bw2 | 2.5YR | 4 | 6 | 60 | 0.2 | 4.8 | 13 | 4.9 | 4.2

Notable features for WRB key:

- Clay 50-60 % throughout, hue 2.5YR, low chroma -> ferralic-like with reddish tint;
- OC 2.0 % at the surface, decreasing with depth;
- Low CEC (5-8 cmol+/kg fine earth) and low BS (13-24 %);
- pH H2O 4.7-4.9, pH KCl 4.0-4.2 -> delta pH negative (no Posic).

# 2. Run the WRB key

`classify_wrb2022()` walks the canonical Ch 4 RSG order (HS -> AT -> … -> RG) and returns the first RSG whose tier-2 gate is satisfied.

    res <- classify_wrb2022(pr)
    res
    #>
    #> ── ClassificationResult (WRB 2022) ──
    #>
    #> Name: Geric Ferric Rhodic Chromic Ferralsol (Clayic, Humic, Dystric, Ochric,
    #> Rubic)
    #> RSG/Order: Ferralsols
    #> Qualifiers: Geric, Ferric, Rhodic, Chromic, Clayic, Humic, Dystric, Ochric,
    #> Rubic, FALSE, FALSE, FALSE, FALSE, TRUE, FALSE, FALSE, FALSE, FALSE, FALSE,
    #> al_ox_pct, fe_ox_pct, phosphate_retention_pct, volcanic_glass_pct, FALSE,
    #> volcanic_glass_pct, FALSE, FALSE, plinthite_pct, FALSE, plinthite_pct, FALSE,
    #> plinthite_pct, FALSE, top_cm, bottom_cm, FALSE, TRUE, TRUE, TRUE, FALSE, FALSE,
    #> redoximorphic_features_pct, FALSE, redoximorphic_features_pct, FALSE, FALSE,
    #> p_mehlich3_mg_kg, FALSE, p_mehlich3_mg_kg, FALSE, FALSE, FALSE, FALSE, FALSE,
    #> FALSE, TRUE, FALSE, FALSE, TRUE, TRUE, FALSE, FALSE, FALSE, FALSE, TRUE, FALSE,
    #> TRUE, FALSE
    #> Evidence grade: A
    #>
    #> ── Ambiguities
    #> - TC: Indeterminate -- missing 3 attribute(s): artefacts_pct,
    #> geomembrane_present, technic_hardmaterial_pct
    #> - CR: Indeterminate -- missing 1 attribute(s): permafrost_temp_C
    #> - VR: Indeterminate -- missing 1 attribute(s): slickensides
    #> - SC: Indeterminate -- missing 1 attribute(s): ec_dS_m
    #> - PZ: Indeterminate -- missing 2 attribute(s): al_ox_pct, fe_ox_pct
    #> - PT: Indeterminate -- missing 1 attribute(s): plinthite_pct
    #> - ST: Indeterminate -- missing 1 attribute(s): redoximorphic_features_pct
    #>
    #> ── Missing data that would refine result
    #> artefacts_pct, geomembrane_present, technic_hardmaterial_pct,
    #> permafrost_temp_C, slickensides, ec_dS_m, redoximorphic_features_pct,
    #> al_ox_pct, fe_ox_pct, phosphate_retention_pct, volcanic_glass_pct,
    #> plinthite_pct
    #>
    #> ── Warnings
    #> ! 12 distinct attribute(s) missing across the key trace -- see $missing_data
    #>
    #> ── Key trace
    #> (16 RSGs tested before assignment)
    #> 1. HS Histosols -- failed
    #> 2. AT Anthrosols -- failed
    #> 3. TC Technosols -- NA (3 attrs missing)
    #> 4. CR Cryosols -- NA (1 attrs missing)
    #> 5. LP Leptosols -- failed
    #> 6. SN Solonetz -- failed
    #> 7. VR Vertisols -- NA (1 attrs missing)
    #> 8. SC Solonchaks -- NA (1 attrs missing)
    #> 9. GL Gleysols -- failed (1 attrs missing)
    #> 10. AN Andosols -- failed (4 attrs missing)
    #> 11. PZ Podzols -- NA (2 attrs missing)
    #> 12. PT Plinthosols -- NA (1 attrs missing)
    #> 13. PL Planosols -- failed
    #> 14. ST Stagnosols -- NA (1 attrs missing)
    #> 15. NT Nitisols -- failed
    #> 16. FR Ferralsols -- PASSED

The returned `ClassificationResult` carries:

- `$rsg_or_order` – the assigned Reference Soil Group (here, Ferralsols);
- `$name` – the full Ch 6 name with principal and supplementary qualifiers;
- `$qualifiers` – the resolved principal and supplementary lists, plus the per-qualifier trace;
- `$trace` – the RSG-by-RSG key trace, including which RSGs failed before the assignment;
- `$evidence_grade` – A through D, summarising the provenance of the classification.

# 3. Inspect the principal qualifier resolution

After the RSG is assigned, the resolver walks the canonical Ch 4 principal-qualifier list for that RSG (e.g. for Ferralsols: `Vetic, Posic, Acric, Lixic, Geric, Hyperdystric, ...`) and tests each against the pedon.

    qres <- resolve_wrb_qualifiers(pr, "FR")
    qres$principal
    #> [1] "Geric"   "Ferric"  "Rhodic"  "Chromic"

The four principals that pass the Ferralsol fixture, in canonical Ch 4 order:

    #>   Qualifier
    #> 1     Geric
    #> 2    Ferric
    #> 3    Rhodic
    #> 4   Chromic
    #>                                                                                                                                               Why
    #> 1 ECEC = sum of bases + Al_KCl <= 1.5 cmol+/kg fine earth in some layer of the upper 100 cm. Layer 4 (Bw1, top = 65 cm) has ECEC = 1.18 cmol+/kg.
    #> 2                                                                         Iron-rich subsoil (Fe_dcb >= 5%); fe_dcb_pct hits 8-9% in this fixture.
    #> 3                                   Hue 2.5YR moist, value < 4 in 25-150 cm. Bw1 has value = 4 (failing in some layers but BA satisfies value 3).
    #> 4                                                              Hue redder than 7.5YR + chroma > 4 in 25-150 cm subsoil. Bw1 chroma = 6 satisfies.

The `trace` slot keeps every Ch 4 principal that was tested, including those that failed. Useful for diagnostic debugging:

    trace_df <- do.call(
      rbind,
      lapply(names(qres$trace), function(q) {
        t <- qres$trace[[q]]
        data.frame(qualifier = q,
                   passed    = if (is.null(t$passed)) NA else t$passed,
                   note      = t$note %||% "")
      })
    )
    head(trace_df, 12)
    #>       qualifier passed note
    #> 1         Vetic  FALSE
    #> 2         Posic  FALSE
    #> 3         Acric  FALSE
    #> 4         Lixic  FALSE
    #> 5         Geric   TRUE
    #> 6  Hyperdystric  FALSE
    #> 7   Hypereutric  FALSE
    #> 8        Histic  FALSE
    #> 9         Folic  FALSE
    #> 10        Andic  FALSE
    #> 11       Vitric  FALSE
    #> 12      Sombric  FALSE

# 4. Inspect the supplementary qualifier resolution

Supplementary qualifiers are the parenthesised tags in the WRB Ch 6 name. They refine the soil description with texture / chemistry / colour information that is not strong enough to be a principal but still informative.

    qres$supplementary
    #> [1] "Clayic"  "Humic"   "Dystric" "Ochric"  "Rubic"

What each tag captures for this Ferralsol:

    #>   Qualifier
    #> 1    Clayic
    #> 2     Humic
    #> 3   Dystric
    #> 4    Ochric
    #> 5     Rubic
    #>                                                                                                Why
    #> 1 Clay >= 60 % over a layer thicker than 30 cm in the upper 100 cm; Bw1 has clay = 60% over 65 cm.
    #> 2                                 Weighted OC >= 1 % in the upper 50 cm; weighted OC ~ 1.1 % here.
    #> 3                       BS < 50 % throughout 20-100 cm; BS = 13-24 % across all four upper layers.
    #> 4                      OC >= 0.2 % in upper 10 cm + no mollic + no umbric; surface has OC = 2.0 %.
    #> 5         Hue <= 5YR + chroma >= 4 in upper 100 cm (less strict than Rhodic). 2.5YR / 6 satisfies.

# 5. Compose the Ch 6 name

`format_wrb_name()` glues principal and supplementary into the canonical form:

    format_wrb_name(
      rsg_name      = "Ferralsols",
      principal     = qres$principal,
      supplementary = qres$supplementary
    )
    #> [1] "Geric Ferric Rhodic Chromic Ferralsol (Clayic, Humic, Dystric, Ochric, Rubic)"

This is exactly the string returned by `classify_wrb2022()$name`.

# 6. Family suppression

When several qualifiers from the same WRB family (e.g. Calcic / Hypocalcic / Protocalcic) pass the same RSG, only the most-specific sibling appears in the name. The suppression is applied after all candidates are evaluated and works on both the principal and supplementary lists.

The internal table:

    str(soilKey:::.wrb_qualifier_families)
    #> List of 10
    #>  $ salinity: chr [1:3] "Hypersalic" "Salic" "Hyposalic"
    #>  $ sodicity: chr [1:3] "Hypersodic" "Sodic" "Hyposodic"
    #>  $ calcic  : chr [1:4] "Hypercalcic" "Calcic" "Hypocalcic" "Protocalcic"
    #>  $ gypsic  : chr [1:4] "Hypergypsic" "Gypsic" "Hypogypsic" "Protogypsic"
    #>  $ vertic  : chr [1:2] "Vertic" "Protovertic"
    #>  $ albic   : chr [1:2] "Hyperalbic" "Albic"
    #>  $ skeletic: chr [1:2] "Hyperskeletic" "Skeletic"
    #>  $ eutric  : chr [1:2] "Hypereutric" "Eutric"
    #>  $ dystric : chr [1:2] "Hyperdystric" "Dystric"
    #>  $ alic    : chr [1:2] "Hyperalic" "Alic"

A worked example: a synthetic Calcisol that satisfies Calcic, Hypocalcic, and Protocalcic simultaneously will collapse to just Calcic.

    soilKey:::.suppress_qualifier_siblings(
      c("Mollic", "Calcic", "Hypocalcic", "Protocalcic", "Cambic")
    )
    #> [1] "Mollic" "Calcic" "Cambic"

# 7. Evidence grade

`classify_wrb2022()` reports an `evidence_grade` summarising the provenance of every attribute used in the classification. A means every used value was lab-measured; D means the result rests on VLM-extracted or user-assumed values.

    res$evidence_grade
    #> [1] "A"

The Ferralsol fixture has all measured values, so the grade is A. The `v01_getting_started` vignette shows how `pedon$add_measurement()` with `source = "extracted_vlm"` or `source = "predicted_spectra"` lowers the grade – so you always know how robust the classification is.

# 6. Render a self-contained pedologist-facing report

The `report()` generic takes a `ClassificationResult` (or a list of them, or a `PedonRecord` – in which case all three keys are run automatically) and writes a single-file HTML report with inline CSS, no external network requests, suitable for archiving with a laudo. The PDF path goes through `rmarkdown::render()` and requires a working LaTeX engine.

    # Pass the three classifications as a list:
    results <- list(
      classify_wrb2022(pr),
      classify_sibcs(pr, include_familia = TRUE),
      classify_usda(pr)
    )
    out_html <- file.path(tempdir(), "perfil_ferralsol.html")
    report(results, file = out_html, pedon = pr)

    # Or pass the pedon directly and let report() run the three keys:
    report(pr, file = out_html)

    # Same content as PDF (requires LaTeX):
    # report(pr, file = file.path(tempdir(), "perfil_ferralsol.pdf"))

The HTML output includes: the cross-system summary, the full key trace per system, qualifiers (principal + supplementary), evidence grade, ambiguities, missing data, the horizons table, and the per-source provenance summary. `ClassificationResult$report(file)` is the R6-method-style equivalent and delegates to the same code.

# Summary

    #> WRB 2022 name : Geric Ferric Rhodic Chromic Ferralsol (Clayic, Humic, Dystric, Ochric, Rubic)
    #> Assigned RSG  : Ferralsols
    #> Principal     : Geric, Ferric, Rhodic, Chromic
    #> Supplementary : Clayic, Humic, Dystric, Ochric, Rubic
    #> Evidence grade: A

The `v03_cross_system_correlation` vignette runs the same profile through the Brazilian SiBCS and the USDA Soil Taxonomy keys and shows the alignment between the three classifications.