Dallam County Soil Data
Dallam County, Texas
USDA SSURGO / PHZMAvg pH
7.7
Texture
Sandy Loam
Drainage
N/A
Organic Matter
1.2%
Hydrologic Group
D
Data Story
About Soil in Dallam County, Texas
Strongly Alkaline Panhandle Soils
Dallam County sits at the tip of the Texas Panhandle with a strongly alkaline average pH of 7.74. This is much higher than the Texas average of 7.09 and the national median of 6.5. This chemical profile is common in the semi-arid High Plains where calcium carbonate often accumulates near the surface.
Sandy Soils of the High Plains
The soil composition is 56.4% sand, 24.8% silt, and 18.9% clay, creating a light and airy texture. This high sand content makes the soil easy to cultivate but susceptible to wind erosion if left uncovered. The low clay fraction means the soil has less natural 'glue' to hold it together during dry periods.
Exceptional Water Storage Capacity
While organic matter is low at 1.18%, the available water capacity is a robust 0.144 in/in. This exceeds the state average of 0.133 in/in, making the soil surprisingly good at holding onto every drop of scarce rainfall. This high capacity is a lifesaver for the corn and wheat crops that dominate the region.
Slow Infiltration in Group D Soils
Despite the sandy texture, these soils are in hydrologic group D, indicating very slow infiltration and high runoff potential at depth. This suggests a restrictive layer, like a caliche bed, may exist beneath the surface sand. Landowners should be aware that water may sit on the surface longer than expected during intense storms.
Cold Winters in Hardiness Zone 6b
As the coldest part of Texas, Dallam County is in hardiness zone 6b, requiring plants that can survive significant freezes. The sandy, high-capacity soil is excellent for cool-season vegetables like kale, carrots, and potatoes. Start your northernmost Texas garden today by choosing cold-hardy varieties that love the alkaline soil.
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: Sandy Loam
Typical soil profile. Actual depths vary by location.
USDA Soil Orders
Alkaline Soil Detected
Your county's average pH is 7.7. These products help acidify soil for better nutrient uptake.
Browse Soil AmendmentsFrequently Asked Questions
What type of soil does Dallam County have?
Dallam County's soil is classified as Sandy Loam. This indicates the relative proportions of sand, silt, and clay — 56% sand, 25% silt, and 19% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Dallam County's soil acidic or alkaline?
Dallam County's soil has a pH of 7.7, which is mildly to moderately alkaline. Sulfur amendments can lower pH if needed.
What is the drainage class for Dallam County?
Drainage class data is not currently available for Dallam County.
What crops or plants grow well in Dallam County's soil?
Based on Dallam County's Sandy Loam texture, pH of 7.7, 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 Dallam County?
The dominant USDA soil order for Dallam County is not currently available in our dataset.
Soil & Planting Advisory: Dallam County
Soil Verdict
Dallam County is in USDA hardiness zone 6b, a moderate climate zone. where winter lows can reach -5°F. Freeze-thaw cycles are moderate; soil biology slows in winter but recovers reliably in spring, supporting a broad range of plants.
Planting Guidance
A wide plant palette is possible: deciduous trees, most shrubs, cool-season vegetables, and many perennials thrive here. Winter protection (mulch, burlap wraps) helps push the zone boundary for desired species. 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
Moderate freeze-thaw cycles naturally aerate the soil but can also cause compaction in clay-heavy areas; annual core aeration is beneficial. Organic matter amendments decompose at a moderate pace — aim for 3-5% organic content for optimal fertility. When soil temperatures drop below freezing, microbial nitrogen cycling stops; spring fertilization is more effective than late-fall application.
Regional Context
Dallam County is significantly cooler than the Texas average, shifting effective hardiness by roughly 2.2 zones.
Planning your lawn? View lawn care data for Dallam 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.