Washington County Soil Data
Washington County, Oregon
Avg pH
5.3
Texture
Silt Loam
Drainage
N/A
Organic Matter
26.9%
Hydrologic Group
N/A
Data Story
About Soil in Washington County, Oregon
Acidic Profiles with High Potential
Washington County averages a pH of 5.34, which is slightly more alkaline than the Oregon state average of 5.26 but far below the national median of 6.5. This acidic profile is typical for the region's productive agricultural lands. With a soil score of 75.1, these grounds outperform the state average of 70.2.
Silt-Heavy Soils Drive Workability
The soil composition is dominated by 55.1% silt and 21.6% clay, balanced by 25.7% sand. This high silt content provides excellent workability but requires careful management to prevent erosion. The clay fraction helps retain essential nutrients for seasonal crops.
Exceptional Organic Matter Levels
Organic matter reaches a massive 26.92%, dwarfing the national average of 2.0% while sitting just below the Oregon average of 29.41%. The available water capacity of 0.279 in/in also exceeds the state benchmark of 0.275. This combination creates a highly fertile environment for intense cultivation.
Complex Water Movement Patterns
Specific drainage and hydrologic group classifications are not provided in the current dataset. Given the high silt and clay content, water likely moves slowly through the soil profile compared to sandier regions. Local builders should prioritize site-specific drainage assessments for new foundations.
Bountiful Harvesters in Zone 8b
In USDA Hardiness Zone 8b, these fertile soils support everything from commercial berries to world-class vineyards. The high water capacity ensures plants stay hydrated during the dry Oregon summers. Start your backyard plot today to take advantage of this natural richness.
Soil Composition
Soil pH
Soil Series
Detailed soil series data not yet available for this county.
Hydrologic Group
Hydrologic group data not available.
Drainage Class
Drainage class data not available.
Soil Profile
Dominant texture: Silt Loam
Typical soil profile. Actual depths vary by location.
USDA Soil Orders
Frequently Asked Questions
What type of soil does Washington County have?
Washington County's soil is classified as Silt Loam. This indicates the relative proportions of sand, silt, and clay — 26% sand, 55% silt, and 22% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Washington County's soil acidic or alkaline?
Washington County's soil has a low pH of 5.3, which is strongly acidic. Acidic soils benefit from lime applications to raise pH and improve nutrient availability.
What is the drainage class for Washington County?
Drainage class data is not currently available for Washington County.
What crops or plants grow well in Washington County's soil?
Based on Washington County's Silt Loam texture, pH of 5.3, and drainage class, the soil is well suited for acid-loving plants like blueberries and azaleas, row crops and vegetable gardens.
What USDA soil order is found in Washington County?
The dominant USDA soil order for Washington County is not currently available in our dataset.
Planning your lawn? View lawn care data for Washington County on LawnByCounty.com →
Other Counties in Oregon
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.