Soil series profile

Comfrey soil series

Comfrey is a poorly drained soil with a loam surface, mapped on 94,627 acres in 41 counties across 3 states. Hydrologic group B/D.

#3685 by mapped area fine-loamy Cumulic Endoaquolls (Mollisols)

Drainage class
Poorly drained
89% of mapped acres
Hydrologic group
B/D
>99% of mapped acres
Typical topsoil pH
7.0
neutral · range 6.8–7.2
Mapped area
95k
acres in 41 counties, 3 states

Typical Comfrey profile

Texture and pH by depth

Typical Comfrey soil profile by depth 0 in 20 in 40 in 60 in 0–7 in · H1 · pH 6.9 · 23% clay Loam 7–26 in · H2 · pH 6.9 · 27% clay Loam 26–37 in · H3 · pH 6.9 · 29% clay Silty clay loam 37–63 in · H4 · pH 7.0 · 25% clay Loam
Depth to scale. More strongly shaded layers hold more clay. Horizon names are the soil survey's (A = topsoil, B = subsoil, C = parent material).
Show as a table
Typical Comfrey horizons (representative values)
Depth Texture pH Clay Sand Organic matter
0–7 in (H1) Loam 6.9 23% 30% 6%
7–26 in (H2) Loam 6.9 27% 30% 3.5%
26–37 in (H3) Silty clay loam 6.9 29% 19% 1.35%
37–63 in (H4) Loam 7.0 25% 35% 1%

Representative values from the most extensive Comfrey map unit (Comfrey loam, 0 to 2 percent slopes, frequently flooded, survey area IL201). Other map units of this series vary within the series range.

Hands holding dark garden soil
Stock photo for illustration, not a sample of this soil series. Credit on the Sources & method page.

What this means

What Comfrey soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Comfrey soils is neutral: pH 7.0 (most land between 6.8 and 7.2), the range most vegetables, flowers and lawn grasses prefer.

Loamy topsoil (loam, silt loam and similar) covers >99% of mapped Comfrey acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is loam (60% of mapped Comfrey acres).

>99% of mapped Comfrey acres is somewhat poorly to very poorly drained, so soil stays soggy for long spells after rain and in wet seasons. Raised beds, plants that tolerate wet feet, and not working the soil while wet all help.

For lawns and yards

On >99% of mapped acres, rain soaks in slowly (hydrologic groups C and D, including dual groups that are D until drained). Expect runoff and puddles after heavy rain: core-aerate compacted lawns and keep ground sloping away from foundations.

A seasonal high water table comes within 18 inches of the surface on >99% of mapped acres, often in spring. Basements, sump pumps and lawns in low spots feel it first.

For a septic system

For conventional septic absorption fields, NRCS rates >99% of the acres in mapped Comfrey soils very limited, 0% somewhat limited and 0% not limited.

Where the soil is very limited (slow permeability, a high water table, flooding, shallow bedrock or steep slopes), alternative systems such as mound or sand-filter designs are common and cost more.

Flooding is mapped on >99% of the acres (36% occasional, 63% frequent).

Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.

Generated from the mapped numbers above using fixed rules, not a site visit. See how these notes are written.

Where Comfrey soil is found

Mapped acres

Comfrey is mapped in Illinois, Minnesota and Indiana.

Counties with the most mapped Comfrey soil
County Acres Share of county land
Winnebago County, IL 16,262 5.2%
Ogle County, IL 9,878 2.1%
Blue Earth County, MN 8,122 1.7%
Lee County, IL 7,750 1.7%
McHenry County, IL 7,544 2.1%
Houston County, MN 7,368 2.1%
Benton County, IN 5,827 2.3%
Nobles County, MN 5,081 1.1%
Boone County, IL 3,989 2.3%
Livingston County, IL 3,546 0.5%
Warren County, IN 3,310 1.5%
Iroquois County, IL 2,956 0.4%
Winona County, MN 2,229 0.6%
Cass County, IL 2,078 0.9%
Rock County, MN 1,698 0.5%
Grundy County, IL 1,561 0.6%
Scott County, MN 1,453 0.6%
Newton County, IN 940 0.4%
Cumberland County, IL 668 0.3%
LaSalle County, IL 458 0.1%
Redwood County, MN 354 0.1%
Stephenson County, IL 330 0.1%
DeKalb County, IL 308 0.1%
Whiteside County, IL 205 0.0%
Olmsted County, MN 191 0.0%
Kane County, IL 114 0.0%
Jo Daviess County, IL 97 0.0%
Kendall County, IL 81 0.0%
Wabasha County, MN 62 0.0%
Carroll County, IL 45 0.0%
Cottonwood County, MN 39 0.0%
Will County, IL 27 0.0%
Bureau County, IL 11 0.0%
Murray County, MN 10 0.0%
Tazewell County, IL 10 0.0%
Logan County, IL 8 0.0%
Kankakee County, IL 7 0.0%
Brown County, IL 5 0.0%
Peoria County, IL 4 0.0%
Lake County, IL 2 0.0%
Lyon County, MN 1 0.0%

Septic absorption fields

NRCS rating, share of Comfrey acres

Not limited 0%
Somewhat limited 0%
Very limited >99%
Not rated <1%
Septic tank absorption field rating across mapped Comfrey acres. Scale 0 to 100% of mapped land.
Show as a table
Septic tank absorption field rating across mapped Comfrey acres.
CategoryShare of acres
Not limited0.0%
Somewhat limited0.0%
Very limited99.1%
Not rated0.9%

Drainage, water table and flooding

Share of Comfrey acres

Depth to seasonal high water table
About 6 inches (median where reported); within 18 inches on >99% of acres.
Flooding
Mapped as flooding on >99% of acres (36% occasional, 63% frequent).
Slope
Typically 0–1% (median 0%).
Topsoil organic matter
Median 6%.

Drainage class

Excessively drained 0%
Somewhat excessively drained 0%
Well drained 0%
Moderately well drained 0%
Somewhat poorly drained 0%
Poorly drained 89%
Very poorly drained 11%
Not rated <1%
Drainage class across mapped Comfrey acres. Scale 0 to 100% of mapped land.
Show as a table
Drainage class across mapped Comfrey acres.
CategoryShare of acres
Excessively drained0.0%
Somewhat excessively drained0.0%
Well drained0.0%
Moderately well drained0.0%
Somewhat poorly drained0.0%
Poorly drained88.9%
Very poorly drained10.8%
Not rated0.4%

Hydrologic soil group

A: fast infiltration (mostly sandy or gravelly) 0%
B: moderate infiltration 0%
C: slow infiltration 0%
D: very slow infiltration (clayey, shallow or wet) 0%
A/D: D as is, A if drained 0%
B/D: D as is, B if drained >99%
C/D: D as is, C if drained 0%
Not rated <1%
Hydrologic soil group across mapped Comfrey acres. Scale 0 to 100% of mapped land.
Show as a table
Hydrologic soil group across mapped Comfrey acres.
CategoryShare of acres
A: fast infiltration (mostly sandy or gravelly)0.0%
B: moderate infiltration0.0%
C: slow infiltration0.0%
D: very slow infiltration (clayey, shallow or wet)0.0%
A/D: D as is, A if drained0.0%
B/D: D as is, B if drained99.1%
C/D: D as is, C if drained0.0%
Not rated0.9%

Sources & data dates

Source
USDA NRCS Soil Survey Geographic Database (SSURGO), queried through Soil Data Access. Public domain.
Data date
SSURGO as published on November 3, 2026 (most recent survey area update October 26, 2026). NRCS refreshes SSURGO each October.
Scope
All map unit components named Comfrey (component kind "Series") in SSURGO: 94,627 acres.
Method
Shares are by mapped acres of Comfrey components. The profile comes from the single largest Comfrey component. Full methodology.

Independent reference site. No government affiliation or endorsement.

Full narrative description: USDA Official Soil Series Description for Comfrey.