Colusa County Soil Data
Colusa County, California
USDA SSURGO / PHZMAvg pH
6.2
Texture
Loam
Drainage
N/A
Organic Matter
1.6%
Hydrologic Group
D
Data Story
About Soil in Colusa County, California
Slightly Acidic Valley Floor Soils
Colusa County soils have an average pH of 6.17, making them slightly more acidic than the national median of 6.5. This pH level is also a bit lower than the California state average of 6.34. These conditions are generally favorable for many traditional valley crops.
A Balanced but Substantial Mix
The soil composition features 31.0% sand, 33.8% silt, and 25.9% clay. This relatively even mix provides a solid foundation for nutrient retention, though the clay content requires careful management to avoid compaction. It is a productive but heavy soil to work with.
High Water Capacity Boosts Growth
At 1.61%, the organic matter in Colusa is below the state average of 3.30%. However, its available water capacity of 0.159 in/in exceeds the California average of 0.141 in/in, ensuring your plants stay hydrated longer between waterings.
Managing Slow-Draining Valley Land
The county falls into Hydrologic Group D, characterized by very slow infiltration and high runoff potential. This makes drainage management a priority for local farmers and home builders to prevent waterlogging. Proper irrigation planning is essential for success here.
Thriving in the 9b Sun
Colusa County's Zone 9b climate is legendary for almond and rice production. With a soil score of 45.2, the ground is ready for action; start your own garden with heat-loving melons or a backyard nut tree.
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
Soil Amendment Products
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Browse Soil AmendmentsFrequently Asked Questions
What type of soil does Colusa County have?
Colusa County's soil is classified as Loam. This indicates the relative proportions of sand, silt, and clay — 31% sand, 34% silt, and 26% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Colusa County's soil acidic or alkaline?
Colusa County's soil has a pH of 6.2, which is moderately acidic. This range suits many crops and is common across much of the eastern US.
What is the drainage class for Colusa County?
Drainage class data is not currently available for Colusa County.
What crops or plants grow well in Colusa County's soil?
Based on Colusa County's Loam texture, pH of 6.2, 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 Colusa County?
The dominant USDA soil order for Colusa County is not currently available in our dataset.
Soil & Planting Advisory: Colusa County
Soil Verdict
Colusa County is in USDA hardiness zone 9b, a warm climate zone. where winter lows can reach 25°F. Warm winters keep soil biology active nearly year-round, accelerating decomposition but increasing pest and disease pressure in topsoil.
Planting Guidance
Tropical and subtropical plants are viable. Year-round gardening is possible, though summer heat may limit some cool-season crops. Frost is rare; tender plants can overwinter with minimal protection. 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
Rapid organic matter turnover means soils can become nutrient-poor quickly; test annually and fertilize based on results. High soil temperatures favor certain soilborne pathogens; practice crop rotation and avoid overwatering.
Regional Context
Colusa County closely matches the California average hardiness conditions. The zone range of 9a-9b within the county means soil and planting decisions should account for local elevation and topography.
Planning your lawn? View lawn care data for Colusa 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.