Soil series profile
Tarrant soil series
Tarrant is a well drained soil with a very cobbly clay surface, mapped on 2,936,494 acres in 46 counties across 2 states. Hydrologic group D.
- Drainage class
- Well drained 100% of mapped acres
- Hydrologic group
- D 97% of mapped acres
- Typical topsoil pH
- 7.6 slightly alkaline · range 7.6–7.9
- Mapped area
- 2.9M acres in 46 counties, 2 states
Typical Tarrant profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–8 in (A) | Very cobbly clay | 7.6 | 52% | 10% | 4.5% |
| 8–13 in (Ak) | Extremely cobbly clay | 7.7 | 56% | 7% | 4.5% |
| 13–30 in (R) | Bedrock | Not reported | Not reported | Not reported | Not reported |
What this means
What Tarrant soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Tarrant soils is slightly alkaline: pH 7.6 (most land between 7.6 and 7.9). Acid-loving plants such as blueberries and azaleas struggle without amended beds, and some trees and shrubs show iron chlorosis (yellow leaves with green veins).
Clayey topsoil covers 97% of mapped Tarrant acres. Clay holds water and nutrients but drains slowly and compacts if worked wet: add compost, avoid tilling soggy soil and consider raised beds. The most common surface texture is very cobbly clay (70% of mapped Tarrant acres).
100% of mapped Tarrant acres is moderately well to excessively drained, which suits most garden plants.
For lawns and yards
On 97% of mapped acres, rain soaks in slowly (hydrologic groups C and D, including dual groups that are D until drained). Expect runoff and puddles after heavy rain: core-aerate compacted lawns and keep ground sloping away from foundations.
For a septic system
For conventional septic absorption fields, NRCS rates 97% of the acres in mapped Tarrant soils very limited, 0% somewhat limited and 0% not limited (3% not rated, such as urban land, pits or water).
Where the soil is very limited (slow permeability, a high water table, flooding, shallow bedrock or steep slopes), alternative systems such as mound or sand-filter designs are common and cost more.
Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.
Where Tarrant soil is found
Mapped acres
Tarrant is mapped in Texas and Oklahoma.
| County | Acres | Share of county land |
|---|---|---|
| Sutton County, TX | 520,581 | 55.9% |
| Kimble County, TX | 514,709 | 64.4% |
| Menard County, TX | 391,298 | 67.9% |
| Schleicher County, TX | 305,847 | 36.5% |
| McCulloch County, TX | 217,083 | 31.7% |
| Tom Green County, TX | 178,037 | 18.3% |
| Gillespie County, TX | 174,736 | 25.8% |
| Coleman County, TX | 105,617 | 13.1% |
| Coke County, TX | 85,529 | 14.9% |
| Kinney County, TX | 64,424 | 7.4% |
| Mills County, TX | 49,425 | 10.3% |
| Val Verde County, TX | 38,861 | 1.9% |
| Edwards County, TX | 35,506 | 2.6% |
| Bosque County, TX | 30,888 | 4.9% |
| Crockett County, TX | 30,658 | 1.7% |
| Comanche County, TX | 25,720 | 4.2% |
| Mason County, TX | 23,305 | 3.9% |
| Irion County, TX | 23,017 | 3.4% |
| Concho County, TX | 21,039 | 3.4% |
| Bandera County, TX | 18,547 | 3.7% |
| Sterling County, TX | 12,703 | 2.2% |
| Nolan County, TX | 11,597 | 2.0% |
| Brown County, TX | 9,958 | 1.6% |
| Bryan County, OK | 9,917 | 1.7% |
| Kerr County, TX | 8,325 | 1.2% |
| Runnels County, TX | 5,886 | 0.9% |
| Real County, TX | 5,131 | 1.1% |
| Bell County, TX | 4,035 | 0.6% |
| Medina County, TX | 3,779 | 0.4% |
| Marshall County, OK | 3,268 | 1.4% |
| Coryell County, TX | 2,610 | 0.4% |
| Hamilton County, TX | 942 | 0.2% |
| San Saba County, TX | 680 | 0.1% |
| Lampasas County, TX | 612 | 0.1% |
| Eastland County, TX | 543 | 0.1% |
| Johnston County, OK | 500 | 0.1% |
| Taylor County, TX | 424 | 0.1% |
| Bexar County, TX | 235 | 0.0% |
| Stephens County, TX | 111 | 0.0% |
| Blanco County, TX | 103 | 0.0% |
| McLennan County, TX | 89 | 0.0% |
| Atoka County, OK | 79 | 0.0% |
| Palo Pinto County, TX | 54 | 0.0% |
| Hays County, TX | 37 | 0.0% |
| Burnet County, TX | 28 | 0.0% |
| Comal County, TX | 18 | 0.0% |
Septic absorption fields
NRCS rating, share of Tarrant acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.0% |
| Somewhat limited | 0.0% |
| Very limited | 96.9% |
| Not rated | 3.1% |
Drainage, water table and flooding
Share of Tarrant acres
- Depth to seasonal high water table
- None reported within about 6.5 feet (median where reported).
- Flooding
- Not mapped as flooding on most acres.
- Slope
- Typically 4–12% (median 5%).
- Topsoil organic matter
- Median 4.5%.
Drainage class
Show as a table
| Category | Share of acres |
|---|---|
| Excessively drained | 0.0% |
| Somewhat excessively drained | 0.0% |
| Well drained | 100.0% |
| Moderately well drained | 0.0% |
| Somewhat poorly drained | 0.0% |
| Poorly drained | 0.0% |
| Very poorly drained | 0.0% |
Hydrologic soil group
Show as a table
| Category | Share of acres |
|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 0.0% |
| B: moderate infiltration | 0.0% |
| C: slow infiltration | 0.0% |
| D: very slow infiltration (clayey, shallow or wet) | 97.2% |
| A/D: D as is, A if drained | 0.0% |
| B/D: D as is, B if drained | 0.0% |
| C/D: D as is, C if drained | 0.0% |
| Not rated | 2.8% |
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 map unit components named Tarrant (component kind "Series") in SSURGO: 2,936,494 acres.
- Method
- Shares are by mapped acres of Tarrant components. The profile comes from the single largest Tarrant component. Full methodology.