Soil series profile

Brookston soil series

Brookston is a poorly drained soil with a silty clay loam surface, mapped on 641,641 acres in 93 counties across 4 states. Hydrologic group B/D.

#388 by mapped area fine-loamy Typic Argiaquolls (Mollisols)

Drainage class
Poorly drained
92% of mapped acres
Hydrologic group
B/D
75% of mapped acres
Typical topsoil pH
6.5
slightly acidic · range 6.5–6.7
Mapped area
642k
acres in 93 counties, 4 states

Typical Brookston profile

Texture and pH by depth

Typical Brookston soil profile by depth 0 in 10 in 20 in 30 in 40 in 50 in 0–16 in · Ap · pH 6.5 · 28% clay Silty clay loam 16–32 in · Btg1 · pH 7.0 · 34% clay Silty clay loam 32–44 in · Btg2 · pH 7.2 · 25% clay Loam 44–60 in · C · pH 7.9 · 15% 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 Brookston horizons (representative values)
Depth Texture pH Clay Sand Organic matter
0–16 in (Ap) Silty clay loam 6.5 28% 13% 4%
16–32 in (Btg1) Silty clay loam 7.0 34% 19% 1.25%
32–44 in (Btg2) Loam 7.2 25% 34% 1.25%
44–60 in (C) Loam 7.9 15% 36% 0.75%

Representative values from the most extensive Brookston map unit (Brookston silty clay loam, 0 to 2 percent slopes, survey area IN059). 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 Brookston soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Brookston soils is slightly acidic: pH 6.5 (most land between 6.5 and 6.7), the range most vegetables, flowers and lawn grasses prefer.

Loamy topsoil (loam, silt loam and similar) covers >99% of mapped Brookston acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silty clay loam (48% of mapped Brookston acres).

>99% of mapped Brookston 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 Brookston 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.

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 Brookston soil is found

Mapped acres

Brookston is mapped in Indiana, Michigan, Wisconsin and Ohio. The 60 counties with the most Brookston acres:

Counties with the most mapped Brookston soil
County Acres Share of county land
Hancock County, IN 59,000 30.2%
Shiawassee County, MI 55,326 16.1%
Hamilton County, IN 47,053 18.7%
Shelby County, IN 42,925 16.5%
Madison County, IN 33,132 11.5%
Johnson County, IN 31,334 15.4%
Genesee County, MI 28,058 6.9%
Howard County, IN 27,218 14.6%
Pulaski County, IN 24,822 9.0%
St. Joseph County, IN 20,760 7.1%
Marion County, IN 19,266 7.8%
Elkhart County, IN 19,045 6.4%
Marshall County, IN 18,943 6.7%
Lapeer County, MI 15,474 3.7%
Ingham County, MI 15,030 4.2%
Washtenaw County, MI 14,145 3.1%
Noble County, IN 11,925 4.6%
Oakland County, MI 10,138 1.8%
Lenawee County, MI 10,088 2.1%
Livingston County, MI 9,363 2.6%
Hendricks County, IN 8,520 3.3%
Wabash County, IN 7,639 2.9%
Fond du Lac County, WI 6,886 1.5%
Fayette County, IN 6,714 4.9%
Washington County, WI 5,498 2.0%
Steuben County, IN 5,213 2.7%
Waukesha County, WI 4,801 1.4%
Kosciusko County, IN 4,429 1.3%
Miami County, IN 4,228 1.8%
Saginaw County, MI 4,120 0.8%
St. Clair County, MI 4,107 0.9%
Allegan County, MI 3,787 0.7%
Manitowoc County, WI 3,416 0.9%
Union County, IN 3,345 3.3%
Jasper County, IN 3,312 0.9%
Montgomery County, OH 3,254 1.1%
Darke County, OH 3,243 0.8%
Dodge County, WI 3,226 0.6%
Monroe County, MI 3,222 0.9%
Fayette County, OH 3,092 1.2%
Preble County, OH 2,311 0.9%
Fulton County, IN 2,265 1.0%
Rock County, WI 2,211 0.5%
Miami County, OH 2,175 0.8%
Greene County, OH 2,168 0.8%
Ross County, OH 2,051 0.5%
Hillsdale County, MI 1,995 0.5%
White County, IN 1,815 0.6%
Champaign County, OH 1,523 0.6%
Clark County, OH 1,475 0.6%
Logan County, OH 1,290 0.4%
Calumet County, WI 1,169 0.6%
Ozaukee County, WI 1,009 0.7%
Morgan County, IN 1,008 0.4%
Pickaway County, OH 993 0.3%
Ionia County, MI 960 0.3%
Franklin County, OH 873 0.3%
Clinton County, OH 869 0.3%
Wayne County, IN 819 0.3%
Highland County, OH 743 0.2%

Septic absorption fields

NRCS rating, share of Brookston acres

Not limited 0%
Somewhat limited 0%
Very limited >99%
Not rated <1%
Septic tank absorption field rating across mapped Brookston acres. Scale 0 to 100% of mapped land.
Show as a table
Septic tank absorption field rating across mapped Brookston acres.
CategoryShare of acres
Not limited0.0%
Somewhat limited0.0%
Very limited99.8%
Not rated0.2%

Drainage, water table and flooding

Share of Brookston acres

Depth to seasonal high water table
About 6 inches (median where reported); within 18 inches on >99% of acres.
Flooding
Not mapped as flooding on most acres.
Slope
Typically 0–1% (median 1%).
Topsoil organic matter
Median 4%.

Drainage class

Excessively drained 0%
Somewhat excessively drained 0%
Well drained 0%
Moderately well drained 0%
Somewhat poorly drained 0%
Poorly drained 92%
Very poorly drained 7%
Not rated <1%
Drainage class across mapped Brookston acres. Scale 0 to 100% of mapped land.
Show as a table
Drainage class across mapped Brookston acres.
CategoryShare of acres
Excessively drained0.0%
Somewhat excessively drained0.0%
Well drained0.0%
Moderately well drained0.0%
Somewhat poorly drained0.0%
Poorly drained92.4%
Very poorly drained7.4%
Not rated0.2%

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 75%
C/D: D as is, C if drained 25%
Not rated <1%
Hydrologic soil group across mapped Brookston acres. Scale 0 to 100% of mapped land.
Show as a table
Hydrologic soil group across mapped Brookston 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 drained75.0%
C/D: D as is, C if drained24.8%
Not rated0.2%

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 Brookston (component kind "Series") in SSURGO: 641,641 acres.
Method
Shares are by mapped acres of Brookston components. The profile comes from the single largest Brookston component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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