You can pull this straight from USDA's Soil Data Access (SDA) without going through Web Soil Survey or standing up an ArcGIS query. SDA takes T-SQL over HTTP — POST to
https://SDMDataAccess.sc.egov.usda.gov/Tabular/post.rest. Coordinate → map unit (note: lon-then-lat inside point(), WGS84):
SELECT mukey FROM SDA_Get_Mukey_from_intersection_with_WktWgs84('point(-93.65 42.03)')
That gives you the mukey. For actual properties (pH, AWC, organic matter at a depth window) you then join mapunit → component → chorizon and depth-weight the horizons.
Heads-up: SDA queries can hang ~a minute and there are 100k-row / 32MB caps, so chunk large jobs.
If you just want clean JSON per coordinate without writing the SQL or wiring up an ArcGIS query — I built a free wrapper for exactly this (disclosure: it's mine, free while I
see if it's useful to anyone):
curl "https://soilpoint.dev/v1/soil?lat=42.03&lon=-93.65"
returns:
{"soilSeries":"Nicollet","mapUnitName":"Nicollet loam, 1 to 3 percent slopes","texture":"Loam","drainageClass":"Somewhat poorly
drained","hydrologicGroup":"B/D","ph":6.2,"awc":0.21,"organicMatter":5.3,"depthWindowCm":[0,30],"dataVintage":"2025-09-09"}
It returns soil series / texture / drainage / hydrologic group / pH / AWC / organic matter for the dominant component. Two honest caveats for your use case: it does NOT do
GDD (that's climate, not soil — different dataset) or detailed nutrient panels beyond OM/pH. And it's US-only (SSURGO coverage), 0–30 cm values are best-effort, as-is / not
for regulatory use. It caches + stale-serves when SDA is flaky. Live "try it" box at https://soilpoint.dev/?utm_source=esri — and it returns honest nulls for non-soil map
units (urban land, water).
