Johnson County Soil Data
Johnson County, Indiana
USDA SSURGO / PHZMAvg pH
6.4
Texture
Silt loam
Drainage
Well drained
Organic Matter
3.3%
Hydrologic Group
B
Data Story
About Soil in Johnson County, Indiana
Prime Alfisols Define Johnson County Soils
Johnson County features Alfisols, a highly productive soil order known for its natural fertility. With an average pH of 6.37, these soils sit remarkably close to the national median of 6.5 and remain higher than the Indiana state average of 6.08.
A Perfectly Balanced Silt Loam Mix
The ground here consists of 52.8% silt and 19.4% clay, resulting in a classic silt loam texture. This composition offers an ideal balance of easy workability for farmers and strong nutrient retention for growing crops.
High Water Capacity Fuels Local Growth
The county boasts an available water capacity of 0.208 in/in, surpassing the state average of 0.202. While the 3.35% organic matter is lower than the state average, it still significantly exceeds the national average of 2.0%.
Reliable Natural Drainage for Stable Building
The land is classified as well-drained and falls into Hydrologic Group B, meaning it has a moderate infiltration rate when wet. These characteristics make it excellent for both large-scale agriculture and residential development.
Ideal Conditions for Zone 6a Gardening
The 6a hardiness zone and high 79.6 soil score make Johnson County one of the best spots in Indiana for a home garden. You can successfully grow a wide variety of vegetables, particularly heavy-feeders like corn and tomatoes.
Soil Composition
Soil pH
Soil Series
Detailed soil series data not yet available for this county.
Hydrologic Group
Group B — Moderate Runoff
Moderately deep, moderately well-drained soils with moderate infiltration rates. Good balance of drainage and water retention.
Drainage Class
Well drained
Water is removed from the soil readily but not rapidly. Optimal for most plants and construction.
Soil Profile
Dominant texture: Silt 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 Johnson County have?
Johnson County's soil is classified as Silt loam. This indicates the relative proportions of sand, silt, and clay — 27% sand, 53% silt, and 19% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Johnson County's soil acidic or alkaline?
Johnson County's soil has a pH of 6.4, which is moderately acidic. This range suits many crops and is common across much of the eastern US.
What is the drainage class for Johnson County?
Johnson County has a dominant drainage class of "Well drained." Well-drained soils allow excess water to move through quickly, reducing waterlogging risk and supporting most field and garden crops.
What crops or plants grow well in Johnson County's soil?
Based on Johnson County's Silt loam texture, pH of 6.4, and Well drained, the soil is well suited for vegetables, grains, and most field crops, row crops and vegetable gardens, most annual and perennial crops.
What USDA soil order is found in Johnson County?
Johnson County's dominant soil order is Alfisols. Alfisols are moderate to high base-status soils with a clay-enriched subsoil. They support productive forests and cropland across temperate regions.
Soil & Planting Advisory: Johnson County
Soil Verdict
Johnson County is in USDA hardiness zone 6a, a moderate climate zone. where winter lows can reach -10°F. Freeze-thaw cycles are moderate; soil biology slows in winter but recovers reliably in spring, supporting a broad range of plants.
Planting Guidance
A wide plant palette is possible: deciduous trees, most shrubs, cool-season vegetables, and many perennials thrive here. 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
Moderate freeze-thaw cycles naturally aerate the soil but can also cause compaction in clay-heavy areas; annual core aeration is beneficial. Organic matter amendments decompose at a moderate pace — aim for 3-5% organic content for optimal fertility. When soil temperatures drop below freezing, microbial nitrogen cycling stops; spring fertilization is more effective than late-fall application.
Regional Context
Johnson County closely matches the Indiana average hardiness conditions. The zone range of 6a-6b within the county means soil and planting decisions should account for local elevation and topography.
Planning your lawn? View lawn care data for Johnson County on LawnByCounty.com →
Other Counties in Indiana
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.