- Highest county pH
- 8.5
- Box Elder County, UT
- 25th on the list
- 8.2
- Glasscock County, TX
- Alkaline land, US
- 20%
- share of all mapped land
The 25 most alkaline counties
Typical topsoil pH, highest first
| County | Typical pH | Alkaline land | Most common soil |
|---|---|---|---|
| 1. Box Elder County, UT | 8.5 | 74% | Skumpah |
| 2. Millard County, UT | 8.5 | 84% | Uvada |
| 3. Tooele County, UT | 8.5 | 78% | Skumpah |
| 4. Esmeralda County, NV | 8.3 | 88% | Wardenot |
| 5. Maricopa County, AZ | 8.2 | 83% | Gunsight |
| 6. Yuma County, AZ | 8.2 | 86% | Gunsight |
| 7. Alamosa County, CO | 8.2 | 83% | Hooper |
| 8. Rio Grande County, CO | 8.2 | 79% | Norte |
| 9. Jefferson County, ID | 8.2 | 89% | Terreton |
| 10. Churchill County, NV | 8.2 | 76% | Isolde |
| 11. Clark County, NV | 8.2 | 86% | Weiser |
| 12. Nye County, NV | 8.2 | 75% | Stewval |
| 13. Pershing County, NV | 8.2 | 78% | Mazuma |
| 14. White Pine County, NV | 8.2 | 82% | Palinor |
| 15. Bernalillo County, NM | 8.2 | 83% | Bluepoint |
| 16. De Baca County, NM | 8.2 | 94% | Berwolf |
| 17. Lincoln County, NM | 8.2 | 83% | Deama |
| 18. Otero County, NM | 8.2 | 77% | Lozier |
| 19. San Juan County, NM | 8.2 | 83% | Sheppard |
| 20. Valencia County, NM | 8.2 | 88% | Madurez |
| 21. Cameron County, TX | 8.2 | 79% | Laredo |
| 22. Concho County, TX | 8.2 | 85% | Cho |
| 23. Coryell County, TX | 8.2 | 75% | Real |
| 24. El Paso County, TX | 8.2 | 81% | Hueco |
| 25. Glasscock County, TX | 8.2 | 93% | Reagan |
Why these soils are alkaline
Dry climates do not wash calcium carbonate out of the soil, so it collects in the upper layers, sometimes as a hard white layer called caliche. Soils formed from limestone or from old lake and sea beds add more. A few of these counties also have salty or sodic soils, which push pH higher still.
Gardening in alkaline soil
Above about pH 7.8, plants have trouble taking up iron, manganese and zinc even when the soil holds plenty. The classic sign is yellow leaves with green veins (chlorosis) on young growth. Lowering pH with sulfur works slowly and fights the lime already in the soil, so many gardeners in these counties grow in raised beds, use chelated iron, and choose plants native to the region, which are adapted to it.
Sources & data dates
- Source
- USDA NRCS Soil Survey Geographic Database (SSURGO), queried through Soil Data Access. Public domain.
- Data date
- SSURGO as published on November 3, 2026 (most recent survey area update October 26, 2026). NRCS refreshes SSURGO each October.
- Scope
- All mapped land in the 50 states and DC in the current soil survey.
- Method
- County rankings include counties with at least 100,000 acres of mapped land and soil ratings on at least 80% of it, so a small county with one unusual map unit cannot top the list. Counties without a full report on this site are named but not linked; the ZIP lookup covers them. Counties also need a pH reading on at least half their land. Alkaline means topsoil pH 7.4 or above. Full methodology.