Adams County Soil Data
Adams County, Washington
USDA SSURGO / PHZMAvg pH
7.3
Texture
Cobbly loam
Drainage
Well drained
Organic Matter
1.3%
Hydrologic Group
B
Data Story
About Soil in Adams County, Washington
Alkaline Aridisols of the High Desert
Adams County features alkaline Aridisols with a pH of 7.35, which is significantly higher than the national median of 6.5. This cobbly loam texture reflects the dry, rugged environment characteristic of eastern Washington.
A Gritty and Silt-Heavy Mix
The soil consists of 40.4% sand and 48.1% silt, creating a balanced but somewhat gritty profile. With only 8.6% clay, these soils are easy to work but may struggle to hold onto nutrients compared to heavier clay-based soils.
Managing Moisture in Dry Ground
Organic matter sits at 1.35%, falling below the state average of 14.85% and the national average of 2.0%. The available water capacity of 0.166 in/in indicates a need for careful irrigation to maximize growing potential in this thirsty soil.
Well-Drained Ground for Stable Use
These soils are well drained and belong to hydrologic group B, which helps prevent pooling during heavy rains. This efficient drainage makes the land suitable for both dryland farming and stable construction projects.
Hardy Crops for Zone 7a
In hardiness zone 7a, this soil supports robust wheat production and drought-tolerant perennials. Start your garden with native species or install drip irrigation to help your vegetables thrive in this arid climate.
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: Cobbly 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 Adams County have?
Adams County's soil is classified as Cobbly loam. This indicates the relative proportions of sand, silt, and clay — 40% sand, 48% silt, and 9% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Adams County's soil acidic or alkaline?
Adams 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 Adams County?
Adams 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 Adams County's soil?
Based on Adams County's Cobbly 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 Adams County?
Adams 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: Adams County
Soil Verdict
Adams 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
Adams County closely matches the Washington average hardiness conditions. The zone range of 6b-7a within the county means soil and planting decisions should account for local elevation and topography.
Planning your lawn? View lawn care data for Adams 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.