The HWSD (Harmonized World Soil Database) layer provides comprehensive soil characterization based on HWSD version 2.0, the most authoritative global soil database jointly developed by FAO, IIASA, ISRIC, and JRC.
The database maps 34 WRB (World Reference Base) soil groups at approximately 1 km resolution globally, with detailed soil attributes for 7 depth layers spanning 0–200 cm. These attributes include texture (sand, silt, clay percentages), organic carbon content, pH, cation exchange capacity, bulk density, and available water capacity.
From these raw soil properties, five aggregated quality indices are computed:
| Index | Description | Components |
|---|---|---|
| Composition Index | Soil texture balance | Sand/silt/clay ratios, stoniness |
| Fertility Index | Nutrient availability | Organic carbon, CEC, pH, base saturation |
| Hydraulic Index | Water retention/drainage | Available water capacity, drainage class |
| Productive Limitations | Constraints on agriculture | Depth to bedrock, salinity, sodicity |
| Master Suitability Index | Overall soil quality | Weighted combination of all indices |
Soil data extraction and index computation:
Spatial query — The HWSD raster is clipped to the analysis area, extracting soil mapping units (SMUs)
Attribute retrieval — For each SMU, soil properties are retrieved for up to 7 depth layers:
Index computation — Each index is calculated as a normalized score (0–1):
| Code | Name | Provider | Type | Coverage | Resolution | Version |
|---|---|---|---|---|---|---|
| HWSD v2.0 | Harmonized World Soil Database | FAO/IIASA/ISRIC/JRC | Raster + database | Global | ~1 km (30 arc-sec) | 2.0 (2023) |
Documentation: FAO HWSD
La mappa HWSD (Harmonized World Soil Database) utilizza la versione 2.0 del database globale dei suoli prodotto congiuntamente da FAO, IIASA, ISRIC, ISS-CAS e JRC, con risoluzione di circa 1 km (30 arc-seconds). Il database combina dati da diverse fonti regionali (FAO Digital Soil Map of the World, SOTER, European Soil Database). Il dato raster contiene per ogni pixel un SMU_ID (Soil Mapping Unit ID) che identifica l'unità di suolo. Da un database CSV associato si ottengono per ogni SMU_ID gli attributi dettagliati: - Classe di suolo secondo WRB 2022 (World Reference Base), con 34 gruppi principali (Acrisols, Andosols, Arenosols, Calcisols, Cambisols, Chernozems, Ferralsols, Fluvisols, Gleysols, Histosols, Leptosols, Luvisols, Podzols, Vertisols, ecc.); - Attributi per 7 strati di profondità (D1-D7: 0-5, 5-15, 15-30, 30-60, 60-100, 100-150, 150-200 cm); - Proprietà fisiche: tessitura (sabbia, limo, argilla), densità apparente, pietrosità; - Proprietà chimiche: pH, CEC (capacità di scambio cationico), carbonio organico, azoto totale. Vengono calcolati indici di qualità del suolo: Composition Index (qualità della composizione), Fertility Index (fertilità), Hydraulic Index (proprietà idrauliche), Productive Limitations Index (limitazioni produttive), Master Suitability Index (idoneità complessiva).