Grant County Soil Data
Grant County, Washington
USDA SSURGO / PHZMAvg pH
7.3
Texture
Silt loam
Drainage
Well drained
Organic Matter
1.4%
Hydrologic Group
B
Data Story
About Soil in Grant County, Washington
Classic Aridisols of the Desert
Grant County is dominated by Aridisols with an average pH of 7.28, which is more alkaline than the national median of 6.5. This high pH is typical of arid climates where minerals accumulate rather than leaching away.
Productive Silt Loam Mix
The dominant texture is silt loam, consisting of 50.2% sand and 39.7% silt. This mix, containing only 8.0% clay, offers an excellent balance of root aeration and physical stability for large-scale farming.
Irrigation Drives This Land
Organic matter is measured at 1.40%, falling below the national average of 2.0% and the state average of 14.85%. An available water capacity of 0.151 in/in makes irrigation indispensable for maintaining the county's high agricultural output.
Well-Drained for Building and Farming
The soil is classified as well-drained and belongs to Hydrologic Group B. These properties indicate a moderate infiltration rate, making the land highly suitable for both residential foundations and diverse crop types.
A Potato Growing Powerhouse
Located in Hardiness Zone 7a, Grant County is one of the nation's top producers of potatoes and tree fruits. The well-drained silt loam is ready for your home garden—start planting today and watch it thrive.
Soil Composition
Soil pH
Soil Series
Detailed soil series data not yet available for this county.
Hydrologic Group
Group B — Moderate Runoff
Moderately deep, moderately well-drained soils with moderate infiltration rates. Good balance of drainage and water retention.
Drainage Class
Well drained
Water is removed from the soil readily but not rapidly. Optimal for most plants and construction.
Soil Profile
Dominant texture: Silt loam
Typical soil profile. Actual depths vary by location.
USDA Soil Orders
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Browse Soil AmendmentsFrequently Asked Questions
What type of soil does Grant County have?
Grant County's soil is classified as Silt loam. This indicates the relative proportions of sand, silt, and clay — 50% sand, 40% silt, and 8% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Grant County's soil acidic or alkaline?
Grant County's soil has a pH of 7.3, which is near neutral. This range is ideal for most garden plants and field crops.
What is the drainage class for Grant County?
Grant County has a dominant drainage class of "Well drained." Well-drained soils allow excess water to move through quickly, reducing waterlogging risk and supporting most field and garden crops.
What crops or plants grow well in Grant County's soil?
Based on Grant County's Silt loam texture, pH of 7.3, and Well drained, the soil is well suited for drought-tolerant crops and native grasses, row crops and vegetable gardens, most annual and perennial crops.
What USDA soil order is found in Grant County?
Grant County's dominant soil order is Aridisols. Aridisols are soils of dry environments with low organic matter. They often have salt or calcium carbonate accumulations at depth.
Soil & Planting Advisory: Grant County
Soil Verdict
Grant County is in USDA hardiness zone 7a, a moderate climate zone. where winter lows can reach 0°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. 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
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. When soil temperatures drop below freezing, microbial nitrogen cycling stops; spring fertilization is more effective than late-fall application.
Regional Context
Grant County closely matches the Washington average hardiness conditions. The zone range of 6b-7b within the county means soil and planting decisions should account for local elevation and topography.
Planning your lawn? View lawn care data for Grant County on LawnByCounty.com →
Other Counties in Washington
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.