Sonoma County Soil Data
Sonoma County, California
Avg pH
5.9
Texture
Loam
Drainage
N/A
Organic Matter
4.3%
Hydrologic Group
D
Data Story
About Soil in Sonoma County, California
Acidic foundations for Sonoma wine country
Sonoma's soil is notably acidic with an average pH of 5.90, which falls below the national median of 6.5. This low pH profile is characteristic of the region's diverse coastal and inland landscapes. These conditions require careful management for growers focusing on crops sensitive to high acidity.
A balanced mix of sand and silt
The soil contains a balanced mixture of 40.5% sand, 34.2% silt, and 23.0% clay. This texture provides a versatile environment that allows for decent aeration while retaining enough clay for structural integrity. It offers moderate workability for farmers across the county's rolling hills.
Superior organic matter fuels growth
With 4.34% organic matter, Sonoma far exceeds the state average of 3.30% and the national average of 2.0%. The available water capacity of 0.144 in/in also sits above the California average of 0.141 in/in. These metrics indicate a highly fertile base with excellent nutrient cycling potential.
Slow infiltration challenges water management
The soil belongs to Hydrologic Group D, which typically indicates high runoff potential and slow water movement when wet. While specific drainage class data is limited for this region, this hydrologic profile suggests a need for robust erosion control and drainage infrastructure. Growers should monitor moisture levels closely during heavy winter rains.
Thriving in hardiness zone 9b
Located in USDA hardiness zone 9b, Sonoma's soil and climate perfectly support world-class vineyards, orchards, and cool-season vegetables. The rich organic matter provides an incredible head start for any home gardener looking to plant. Your garden is ready for success in this nutrient-dense environment.
Soil Composition
Soil pH
Soil Series
Detailed soil series data not yet available for this county.
Hydrologic Group
Group D — High Runoff
Clay soils with very slow infiltration rates. Highest runoff potential. These soils have a permanent high water table or are shallow over impervious material.
Drainage Class
Drainage class data not available.
Soil Profile
Dominant texture: Loam
Typical soil profile. Actual depths vary by location.
USDA Soil Orders
Frequently Asked Questions
What type of soil does Sonoma County have?
Sonoma County's soil is classified as Loam. This indicates the relative proportions of sand, silt, and clay — 41% sand, 34% silt, and 23% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Sonoma County's soil acidic or alkaline?
Sonoma County's soil has a pH of 5.9, which is moderately acidic. This range suits many crops and is common across much of the eastern US.
What is the drainage class for Sonoma County?
Drainage class data is not currently available for Sonoma County.
What crops or plants grow well in Sonoma County's soil?
Based on Sonoma County's Loam texture, pH of 5.9, and drainage class, the soil is well suited for vegetables, grains, and most field crops, row crops and vegetable gardens.
What USDA soil order is found in Sonoma County?
The dominant USDA soil order for Sonoma County is not currently available in our dataset.
Planning your lawn? View lawn care data for Sonoma County on LawnByCounty.com →
Other Counties in California
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.