Harmon County Soil Data
Harmon County, Oklahoma
USDA SSURGO / PHZMAvg pH
6.9
Texture
Variable
Drainage
N/A
Organic Matter
1.1%
Hydrologic Group
D
Data Story
About Soil in Harmon County, Oklahoma
Western Oklahoma's Alkaline Profile
Harmon County shares a pH of 6.86 with its neighbors, making it more alkaline than the Oklahoma state average of 6.06. This pH is slightly above the national 6.5 median, which often favors specific crops over acid-loving plants. The county’s soil score of 30.1 suggests a landscape that requires thoughtful management.
Coarse Sand and Variable Textures
With a high sand content of 47.0%, Harmon County has some of the coarsest soil in the region. Silt accounts for 28.1% and clay for 18.3%, creating a profile that drains quickly but lacks some structural cohesion. The dominant texture is classified as variable, reflecting a diverse and changing landscape.
Navigating Low Organic Reserves
At 1.10%, the organic matter in Harmon County is significantly lower than the national 2.0% average. The available water capacity is also lower than the state average at 0.129 in/in. These numbers indicate that plants here may face more stress during the peak of summer heat without supplemental irrigation.
Slow Infiltration Despite Sandy Mix
The soil belongs to Hydrologic Group D, characterized by high runoff and slow infiltration despite the high sand percentage. This can lead to surface crusting which further prevents water from reaching deep root zones. Strategic mulching is often necessary to keep the surface permeable and moist.
Hardy Crops for a 7b Climate
Cotton and sorghum are traditional favorites that can handle the specific soil and 7b hardiness zone of Harmon County. Gardeners should prioritize drought-resistant varieties and consider raised beds to better control soil quality. With its sunny climate, this is a great place for heat-loving succulents and native shrubs.
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: Variable
Typical soil profile. Actual depths vary by location.
USDA Soil Orders
Soil Amendment Products
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Browse Soil AmendmentsFrequently Asked Questions
What type of soil does Harmon County have?
Harmon County's soil is classified as Variable. This indicates the relative proportions of sand, silt, and clay — 47% sand, 28% silt, and 18% clay. Sandy soils drain quickly but may need more frequent irrigation and fertilization.
Is Harmon County's soil acidic or alkaline?
Harmon County's soil has a pH of 6.9, which is near neutral. This range is ideal for most garden plants and field crops.
What is the drainage class for Harmon County?
Drainage class data is not currently available for Harmon County.
What crops or plants grow well in Harmon County's soil?
Based on Harmon County's Variable texture, pH of 6.9, and drainage class, the soil is well suited for vegetables, grains, and most field crops.
What USDA soil order is found in Harmon County?
The dominant USDA soil order for Harmon County is not currently available in our dataset.
Soil & Planting Advisory: Harmon County
Soil Verdict
Harmon County is in USDA hardiness zone 7b, a moderate climate zone. where winter lows can reach 5°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
Harmon County closely matches the Oklahoma average hardiness conditions.
Planning your lawn? View lawn care data for Harmon County on LawnByCounty.com →
Other Counties in Oklahoma
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.