Soil series profile

Keswick soil series

Keswick is a somewhat poorly drained soil with a silt loam surface, mapped on 1,023,767 acres in 75 counties across 2 states. Hydrologic group D.

#172 by mapped area fine Aquertic Chromic Hapludalfs (Alfisols)

Drainage class
Somewhat poorly drained
82% of mapped acres
Hydrologic group
D
79% of mapped acres
Typical topsoil pH
5.9
moderately acidic · range 5.7–5.9
Mapped area
1.0M
acres in 75 counties, 2 states

Typical Keswick profile

Texture and pH by depth

Typical Keswick soil profile by depth 0 in 20 in 40 in 60 in 0–7 in · Ap · pH 5.7 · 22% clay Silt loam 7–20 in · 2Bt · pH 5.5 · 44% clay Clay 20–79 in · 2Btg · pH 6.7 · 39% clay 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 Keswick horizons (representative values)
Depth Texture pH Clay Sand Organic matter
0–7 in (Ap) Silt loam 5.7 22% 26% 2.4%
7–20 in (2Bt) Clay 5.5 44% 25% 1%
20–79 in (2Btg) Clay loam 6.7 39% 23% 0.3%

Representative values from the most extensive Keswick map unit (Keswick silt loam, 5 to 9 percent slopes, eroded, survey area MO027). 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 Keswick soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Keswick soils is moderately acidic: pH 5.9 (most land between 5.7 and 5.9). Many vegetables grow well here, and some gardens benefit from a little lime. Test before adding any.

Loamy topsoil (loam, silt loam and similar) covers 100% of mapped Keswick acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silt loam (61% of mapped Keswick acres).

82% of mapped Keswick 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 100% 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 38% 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 100% of the acres in mapped Keswick 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 Keswick soil is found

Mapped acres

Keswick is mapped in Missouri and Iowa. The 60 counties with the most Keswick acres:

Counties with the most mapped Keswick soil
County Acres Share of county land
Callaway County, MO 92,705 17.3%
Boone County, MO 86,798 19.9%
Macon County, MO 75,986 14.8%
Lincoln County, MO 73,576 18.4%
Randolph County, MO 72,956 23.7%
Pike County, MO 49,265 11.5%
Warren County, MO 48,537 17.7%
Monroe County, MO 47,874 11.5%
Lewis County, MO 42,550 13.3%
Montgomery County, MO 37,183 10.8%
Audrain County, MO 32,025 7.2%
Shelby County, MO 27,726 8.7%
Putnam County, MO 27,685 8.4%
Clark County, MO 26,912 8.3%
Sullivan County, MO 22,997 5.5%
Davis County, IA 19,241 6.0%
Lee County, IA 16,882 5.1%
Decatur County, IA 16,751 5.0%
Howard County, MO 14,705 5.0%
Wapello County, IA 13,717 5.0%
Van Buren County, IA 12,516 4.1%
St. Charles County, MO 11,416 3.2%
Knox County, MO 11,363 3.5%
Appanoose County, IA 11,075 3.5%
Henry County, IA 10,577 3.8%
Keokuk County, IA 10,059 2.7%
Monroe County, IA 9,249 3.3%
Adair County, MO 8,079 2.2%
Linn County, MO 7,508 1.9%
Schuyler County, MO 7,357 3.7%
Lucas County, IA 6,857 2.5%
Iowa County, IA 6,275 1.7%
Washington County, IA 5,670 1.6%
Jefferson County, IA 5,391 1.9%
Chariton County, MO 5,147 1.1%
Mahaska County, IA 4,834 1.3%
Worth County, MO 3,985 2.4%
Marion County, MO 3,684 1.3%
Des Moines County, IA 3,633 1.4%
Scotland County, MO 3,096 1.1%
Clarke County, IA 3,034 1.1%
Johnson County, IA 2,740 0.7%
Marion County, IA 2,664 0.8%
Mercer County, MO 2,081 0.7%
Tama County, IA 1,979 0.4%
Louisa County, IA 1,952 0.8%
Ralls County, MO 1,861 0.6%
Poweshiek County, IA 1,718 0.5%
Cedar County, IA 1,521 0.4%
Ringgold County, IA 1,374 0.4%
Madison County, IA 1,118 0.3%
Johnson County, MO 1,009 0.2%
Warren County, IA 972 0.3%
Jasper County, IA 840 0.2%
Union County, IA 666 0.2%
Jones County, IA 588 0.2%
Linn County, IA 560 0.1%
Muscatine County, IA 504 0.2%
Benton County, IA 492 0.1%
Scott County, IA 484 0.2%

Septic absorption fields

NRCS rating, share of Keswick acres

Not limited 0%
Somewhat limited 0%
Very limited 100%
Septic tank absorption field rating across mapped Keswick acres. Scale 0 to 100% of mapped land.
Show as a table
Septic tank absorption field rating across mapped Keswick acres.
CategoryShare of acres
Not limited0.0%
Somewhat limited0.0%
Very limited100.0%

Drainage, water table and flooding

Share of Keswick acres

Depth to seasonal high water table
About 2.0 feet (24 in) (median where reported); within 18 inches on 38% of acres.
Flooding
Not mapped as flooding on most acres.
Slope
Typically 7–16% (median 10%).
Topsoil organic matter
Median 1.5%.

Drainage class

Excessively drained 0%
Somewhat excessively drained 0%
Well drained 0%
Moderately well drained 18%
Somewhat poorly drained 82%
Poorly drained 0%
Very poorly drained 0%
Drainage class across mapped Keswick acres. Scale 0 to 100% of mapped land.
Show as a table
Drainage class across mapped Keswick acres.
CategoryShare of acres
Excessively drained0.0%
Somewhat excessively drained0.0%
Well drained0.0%
Moderately well drained17.7%
Somewhat poorly drained82.3%
Poorly drained0.0%
Very poorly drained0.0%

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) 79%
A/D: D as is, A if drained 0%
B/D: D as is, B if drained 0%
C/D: D as is, C if drained 21%
Hydrologic soil group across mapped Keswick acres. Scale 0 to 100% of mapped land.
Show as a table
Hydrologic soil group across mapped Keswick 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)78.9%
A/D: D as is, A if drained0.0%
B/D: D as is, B if drained0.0%
C/D: D as is, C if drained21.1%

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 Keswick (component kind "Series") in SSURGO: 1,023,767 acres.
Method
Shares are by mapped acres of Keswick components. The profile comes from the single largest Keswick component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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