Horizons (click a cell to edit)
CSV
Click any cell to edit it. Depths are in centimetres; leave a lab value blank if unmeasured.
Depth profile
Build a pedon on the Pedon tab first.
Attached Vis-NIR spectrum
Horizon attributes (post gap-fill)
Location

Acknowledgements & references

soilKey stands on the shoulders of the soil-science community. The deterministic keys, the tools they run on, and the data that tests them are the work of many others. Thank you.

Classification standards
  • IUSS Working Group WRB (2022). World Reference Base for Soil Resources 2022, 4th edition. International Union of Soil Sciences, Vienna. The reference-soil-group key, qualifiers and diagnostic horizons/properties/materials implemented for the WRB system.
  • Soil Survey Staff (2022). Keys to Soil Taxonomy, 13th edition. USDA-NRCS, Washington, DC. The order-to-subgroup keys and diagnostic criteria for USDA Soil Taxonomy.
  • Santos, H.G. dos, Jacomine, P.K.T., Anjos, L.H.C. dos, et al. (2018). Sistema Brasileiro de Classificacao de Solos (SiBCS), 5th edition. Embrapa, Brasilia. The ordem-to-subgrupo keys, atributos diagnosticos and familia criteria for the Brazilian system.
Built on these R packages
  • aqp -- the ncss-tech team (Dylan E. Beaudette, Andrew G. Brown, and colleagues). Horizon-geometry algorithms, argillic/cambic boundary detection, and the SoilProfileCollection the app interoperates with.
  • SoilTaxonomy -- Andrew G. Brown, Dylan E. Beaudette and colleagues (ncss-tech). The vendored Keys to Soil Taxonomy and WRB 2022 criteria tables used to audit soilKey's own predicates.
  • munsellinterpol -- Glenn Davis. CIE-anchored Munsell <-> XYZ conversion, and identifying the D65->Illuminant C chromatic adaptation and correct roundHVC() usage in soilKey's spectra-to-colour path.
  • mpspline2 -- Brendan Malone and colleagues. Mass-preserving spline harmonisation of horizon data to standard depths.
  • terra, sf, leaflet, shiny, bslib, DT, plotly, ellmer and the wider R ecosystem. Spatial analysis, the interactive map, the application framework, and optional vision-language extraction.
Data sources & services
  • SoilGrids / ISRIC - World Soil Information. Global soil-property and WRB class-probability priors sampled by the Map tab.
  • Open Soil Spectral Library (OSSL) -- Woodwell Climate Research Center, ISRIC and partners. Vis-NIR / MIR spectra with paired laboratory labels for the spectral gap-fill engine.
  • FEBR -- Free Brazilian Repository for Open Soil Data -- Alessandro Samuel-Rosa and contributors. Brazilian profiles with Munsell colours used for benchmarking.
  • Embrapa Solos -- BDSolos and the SmartSolos SiBCS classifier API (Glauber dos S. Vaz). A national soil database and an independent SiBCS reference to cross-check soilKey against.
  • Glauber J. Vaz, Alberto F. Silva Jr & Luis de F. da Silva Neto (2023) -- 'Brazilian soil data for taxonomic classification', Embrapa Redape (DOI 10.48432/PYKKA7). A curated set of ~96 hand-reviewed Brazilian soil profiles, shared as a gold-standard benchmark used to test and calibrate the classifiers.
Review & feedback
  • Glenn Davis (author of munsellinterpol). Colorimetry corrections to the spectra-to-Munsell path (chromatic adaptation and rounding).
  • CRAN and Uwe Ligges. Package review and publication.
If your work is used here and you would like the wording changed, or a credit added or removed, please reach out via Support. This list is maintained on a best-effort basis.
Diagnostic engine
These options set how every classifier reads horizon data. They apply globally to all tabs of this session.
Threshold engine

Which set of numeric thresholds decides whether a horizon meets each diagnostic criterion.


soilKey applies canonical WRB 2022 thresholds; aqp relaxes a few horizon thresholds to match KSSL / regional lab methodology.
WRB Tier-3 strict mode

How deep the classification goes below the reference group or order.

Strengthens per-RSG numerical gates (e.g. Ferralsol CEC, Vertisol clay). Borderline profiles may fall through to a different RSG.
Auto-attach Epi-/Endo-/Bathy-/Amphi- to depth-anchored qualifiers from the feature's depth (e.g. Gleyic -> Endogleyic).
Missing-data policy
Control how missing measurements are handled and how much taxonomic detail the classifiers report.
When an attribute the key needs is absent

What the classifier does when a horizon lacks a value a rule needs.


Silent is recommended in the app -- missing attributes surface in the Classify tab as 'measurements that would refine the result'.
Resolve SiBCS 5th level (familia)

Whether to resolve the deepest, lowest-level categories in each taxonomy.

USDA family prepends class modifiers (particle-size, mineralogy, CEC-activity, temperature regime, ...) to the subgroup name.
soilKey 0.9.184 Transparent, deterministic soil classification -- WRB 2022, SiBCS 5 and USDA Soil Taxonomy. Docs GitHub CRAN GPL-3 | (c) 2026 Hugo Rodrigues