Knox County Soil Data
Knox County, Texas
USDA SSURGO / PHZMAvg pH
7.6
Texture
Loam
Drainage
N/A
Organic Matter
1.2%
Hydrologic Group
D
Data Story
About Soil in Knox County, Texas
Alkaline Soil Profiles in Knox County
The soil in Knox County shows a pH level of 7.59, which is considerably more alkaline than the national median of 6.5. While taxonomic data is limited, the overall soil health score of 22.0 sits below the state average of 28.8.
A Balanced Mix of Sand and Clay
The ground consists of 44.3% sand, 29.7% silt, and 26.0% clay. This moderate clay content provides decent nutrient retention, though the high sand percentage helps with initial workability.
High Water Storage Despite Lower Organic Matter
Organic matter levels sit at 1.18%, which is lower than the Texas state average of 1.66%. However, the available water capacity of 0.144 in/in actually exceeds the state benchmark of 0.133 in/in.
Heavy Runoff Potential in Group D Soils
The county is dominated by hydrologic group D, indicating soil that has a high runoff potential when wet. These soils typically have very slow infiltration rates, requiring careful management during heavy Texas rains.
Gardening Success in Zone 8a
Knox County sits in hardiness zone 8a, which is ideal for winter wheat and cotton. With proper irrigation to manage the alkaline pH, local gardeners can see great success with heat-tolerant vegetables.
Soil Composition
Soil pH
Soil Series
Detailed soil series data not yet available for this county.
Hydrologic Group
Group D — High Runoff
Clay soils with very slow infiltration rates. Highest runoff potential. These soils have a permanent high water table or are shallow over impervious material.
Drainage Class
Drainage class data not available.
Soil Profile
Dominant texture: Loam
Typical soil profile. Actual depths vary by location.
USDA Soil Orders
Alkaline Soil Detected
Your county's average pH is 7.6. These products help acidify soil for better nutrient uptake.
Browse Soil AmendmentsFrequently Asked Questions
What type of soil does Knox County have?
Knox County's soil is classified as Loam. This indicates the relative proportions of sand, silt, and clay — 44% sand, 30% silt, and 26% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Knox County's soil acidic or alkaline?
Knox County's soil has a pH of 7.6, which is mildly to moderately alkaline. Sulfur amendments can lower pH if needed.
What is the drainage class for Knox County?
Drainage class data is not currently available for Knox County.
What crops or plants grow well in Knox County's soil?
Based on Knox County's Loam texture, pH of 7.6, and drainage class, the soil is well suited for drought-tolerant crops and native grasses, row crops and vegetable gardens.
What USDA soil order is found in Knox County?
The dominant USDA soil order for Knox County is not currently available in our dataset.
Soil & Planting Advisory: Knox County
Soil Verdict
Knox County is in USDA hardiness zone 8a, a warm climate zone. where winter lows can reach 10°F. Mild winters mean soil rarely freezes deeply, allowing year-round microbial activity and faster organic matter breakdown.
Planting Guidance
Warm-season crops, citrus relatives, and heat-loving ornamentals do well. Cool-season vegetables should be planted in fall and winter. Always match plant selections to the specific microclimate of your property — low spots, slopes, and wind exposure can shift effective hardiness by half a zone.
Soil Implications
Warm soils accelerate organic matter breakdown, so compost and mulch need replenishing more frequently than in cooler zones. Sandy soils common in warm zones drain quickly; water-retentive amendments like compost or peat help hold moisture.
Regional Context
Knox County closely matches the Texas average hardiness conditions.
Planning your lawn? View lawn care data for Knox County on LawnByCounty.com →
Other Counties in Texas
Soil data sourced from USDA SSURGO via Soil Data Access. Data is informational only and should not be used as a substitute for on-site soil testing. Contact your local NRCS office for site-specific soil information.