Polk County Soil Data
Polk County, Oregon
Avg pH
5.4
Texture
Silt Loam
Drainage
N/A
Organic Matter
16.4%
Hydrologic Group
N/A
Data Story
About Soil in Polk County, Oregon
Willamette Valley Soil Identity
Polk County's soil carries an average pH of 5.44, sitting well below the national 6.5 neutral point. This acidic profile is common across the Willamette Valley and slightly exceeds the state average of 5.26. Such conditions are ideal for the region's famous vineyards and berry farms.
The Balance of Silt and Clay
The soil composition is dominated by 51.5% silt and 24.9% clay, providing strong structure and nutrient storage. With sand making up only 22.3%, the soil holds together well but requires careful management to avoid compaction. This mix is excellent for retaining the moisture necessary for summer crops.
High Organic Matter for Harvests
Polk County features 16.37% organic matter, which is exceptionally high compared to the 2.0% national average. Although it is lower than the 29.41% state average, it still offers incredible natural fertility. The available water capacity of 0.235 in/in supports consistent growth during the dry season.
Managing Water in Valley Soils
The high clay and silt content suggests that drainage may be slow in certain low-lying areas. Farmers here often manage water carefully to prevent oversaturation during wet Oregon winters. Understanding these hydrologic properties is key for maintaining healthy root systems in local orchards.
Bountiful Options in Zone 8b
As a zone 8b region, Polk County is a gardener’s paradise for cool-season crops and perennials. The combination of acidic soil and a mild climate is perfect for wine grapes, hazelnuts, and cherries. It is time to plant your roots in this productive valley soil.
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 Polk County have?
Polk County's soil is classified as Silt Loam. This indicates the relative proportions of sand, silt, and clay — 22% sand, 51% silt, and 25% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Polk County's soil acidic or alkaline?
Polk County's soil has a low pH of 5.4, which is strongly acidic. Acidic soils benefit from lime applications to raise pH and improve nutrient availability.
What is the drainage class for Polk County?
Drainage class data is not currently available for Polk County.
What crops or plants grow well in Polk County's soil?
Based on Polk County's Silt Loam texture, pH of 5.4, 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 Polk County?
The dominant USDA soil order for Polk County is not currently available in our dataset.
Planning your lawn? View lawn care data for Polk 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.