Study area
Set a pin for a single map unit, or draw a polygon to list every SSURGO unit the shape crosses.
SSURGO fields (what the numbers mean)
Soil survey map symbols (e.g. on WMS) are shorthand. Tabular SSURGO adds interpretive fields—still not a substitute for field infiltration tests or groundwater monitoring.
- HSG (hydrologic soil group)
- NRCS classes A–D (and dual symbols) describing relative runoff potential from the soil profile. They support hydrologic methods (e.g. curve number thinking) but do not give a site-specific infiltration rate.
- Ksat (saturated hydraulic conductivity)
- From the shallowest horizon in the profile, in µm/s (shown with an approximate in/hr conversion). Compare components and map units; compacted or filled site soils often behave differently than the map.
- Runoff class
- NRCS qualitative surface-runoff potential for that component—not calibrated inches/hour. Use with HSG, slope, cover, and drainage class.
- Drainage class
- How water moves through the soil profile in the survey’s conceptual model (e.g. well drained vs poorly drained). It supports wetness risk screening, not a measured water table.
- Water table depth (map unit)
- Where present, wtdepannmin / wtdepaprjunmin are depths in centimeters from the soil surface to interpreted shallow saturation for part of the year. Many upland units have no value populated.
- Map unit vs component
- A map unit is the polygon label on the map. Components are soil bodies inside it with percent composition. Major components drive many summaries; complex units mix several soils.