Ada County Soil Data
Ada County, Idaho
USDA SSURGO / PHZMAvg pH
6.8
Texture
Stones, boulders
Drainage
N/A
Organic Matter
4.0%
Hydrologic Group
A
Data Story
About Soil in Ada County, Idaho
Stony Soils with Neutral pH
Ada County's soil shows a slightly alkaline pH of 6.81, which sits just above the national median of 6.5 and exceeds the Idaho state average of 6.04. The terrain features a dominant texture of stones and boulders, making it more rugged than typical valley farmland. This mineral-rich environment requires specific management to ensure uniform plant growth.
Silt and Sand Dominance
The local mix contains 38.3% sand and 43.0% silt, balanced by a relatively low 15.7% clay content. This silt-heavy profile provides a fine texture that holds some nutrients while the sand ensures the ground doesn't become overly compacted. It offers moderate workability, though the low clay means it lacks the natural binding seen in heavier soils.
High Organic Matter, Low Water Capacity
Organic matter stands at 4.04%, which is double the national average of 2.0% but significantly lower than the Idaho state average of 27.53%. With an available water capacity of 0.162 in/in, these soils hold less moisture than the state benchmark of 0.269 in/in. Gardeners should expect to irrigate more frequently to sustain healthy crop growth during dry spells.
High Infiltration and Fast Drainage
Hydrologic Group A classification indicates high infiltration rates and a low runoff potential across the county. While specific drainage class data is unavailable, the Group A status and stony texture suggest that water moves quickly through the soil profile. This is ideal for avoiding root rot but requires careful nutrient management to prevent leaching.
A Garden Oasis in Zone 7a
Located in Hardiness Zone 7a, Ada County is perfect for growing everything from lavender and grapes to heat-loving tomatoes. The well-draining soil and warmer climate provide an excellent foundation for a productive home garden. Start by adding compost to boost water retention and jumpstart your growing season.
Soil Composition
Soil pH
Soil Series
Detailed soil series data not yet available for this county.
Hydrologic Group
Group A — Low Runoff
Sandy, well-drained soils with high infiltration rates. Water moves quickly through the soil profile. Lowest runoff potential when thoroughly wetted.
Drainage Class
Drainage class data not available.
Soil Profile
Dominant texture: Stones, boulders
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 Ada County have?
Ada County's soil is classified as Stones, boulders. This indicates the relative proportions of sand, silt, and clay — 38% sand, 43% silt, and 16% clay. Sandy soils drain quickly but may need more frequent irrigation and fertilization.
Is Ada County's soil acidic or alkaline?
Ada County's soil has a pH of 6.8, which is near neutral. This range is ideal for most garden plants and field crops.
What is the drainage class for Ada County?
Drainage class data is not currently available for Ada County.
What crops or plants grow well in Ada County's soil?
Based on Ada County's Stones, boulders texture, pH of 6.8, and drainage class, the soil is well suited for vegetables, grains, and most field crops.
What USDA soil order is found in Ada County?
The dominant USDA soil order for Ada County is not currently available in our dataset.
Soil & Planting Advisory: Ada County
Soil Verdict
Ada 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
Ada County is somewhat warmer than the Idaho statewide average.
Planning your lawn? View lawn care data for Ada County on LawnByCounty.com →
Other Counties in Idaho
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.