Soil series profile

Mexico soil series

Mexico is a poorly drained soil with a silt loam surface, mapped on 744,330 acres in 22 counties in MO. Hydrologic group D.

#300 by mapped area fine Vertic Epiaqualfs (Alfisols)

Drainage class
Poorly drained
100% of mapped acres
Hydrologic group
D
100% of mapped acres
Typical topsoil pH
6.5
slightly acidic · range 6.5–6.5
Mapped area
744k
acres in 22 counties, 1 state

Typical Mexico profile

Texture and pH by depth

Typical Mexico soil profile by depth 0 in 20 in 40 in 60 in 0–7 in · Ap · pH 6.5 · 18% clay Silt loam 7–15 in · Btg1 · pH 5.7 · 25% clay Silt loam 15–34 in · Btg2 · pH 5.5 · 59% clay Clay 34–42 in · Btg3 · pH 5.7 · 32% clay Silty clay loam 42–79 in · 2Btg4 · pH 5.7 · 30% clay Silty 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 Mexico horizons (representative values)
Depth Texture pH Clay Sand Organic matter
0–7 in (Ap) Silt loam 6.5 18% 5% 1.87%
7–15 in (Btg1) Silt loam 5.7 25% 10% 1.02%
15–34 in (Btg2) Clay 5.5 59% 2% 1.5%
34–42 in (Btg3) Silty clay loam 5.7 32% 2% 0.34%
42–79 in (2Btg4) Silty clay loam 5.7 30% 4% 0.34%

Representative values from the most extensive Mexico map unit (Mexico silt loam, 1 to 4 percent slopes, eroded, survey area MO007). 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 Mexico soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Mexico soils is slightly acidic: pH 6.5, the range most vegetables, flowers and lawn grasses prefer.

Loamy topsoil (loam, silt loam and similar) covers 100% of mapped Mexico acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silt loam (>99% of mapped Mexico acres).

100% of mapped Mexico 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 100% 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 Mexico 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 Mexico soil is found

Mapped acres

Mexico is mapped in Missouri.

Counties with the most mapped Mexico soil
County Acres Share of county land
Audrain County, MO 155,399 35.0%
Montgomery County, MO 83,770 24.4%
Monroe County, MO 76,474 18.4%
Shelby County, MO 71,611 22.4%
Callaway County, MO 64,951 12.1%
Ralls County, MO 56,474 18.7%
Pike County, MO 54,404 12.7%
Boone County, MO 40,009 9.2%
Lincoln County, MO 36,561 9.1%
Randolph County, MO 33,594 10.9%
Marion County, MO 22,546 8.1%
Warren County, MO 18,425 6.7%
St. Charles County, MO 9,295 2.6%
Knox County, MO 9,082 2.8%
Macon County, MO 7,607 1.5%
Lewis County, MO 1,472 0.5%
Adair County, MO 818 0.2%
Clark County, MO 728 0.2%
Howard County, MO 501 0.2%
Linn County, MO 434 0.1%
Schuyler County, MO 153 0.1%
Scotland County, MO 23 0.0%

Septic absorption fields

NRCS rating, share of Mexico acres

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

Drainage, water table and flooding

Share of Mexico acres

Depth to seasonal high water table
About 8 inches (median where reported); within 18 inches on 100% of acres.
Flooding
Not mapped as flooding on most acres.
Slope
Typically 1–2% (median 2%).
Topsoil organic matter
Median 1.9%.

Drainage class

Excessively drained 0%
Somewhat excessively drained 0%
Well drained 0%
Moderately well drained 0%
Somewhat poorly drained 0%
Poorly drained 100%
Very poorly drained 0%
Drainage class across mapped Mexico acres. Scale 0 to 100% of mapped land.
Show as a table
Drainage class across mapped Mexico acres.
CategoryShare of acres
Excessively drained0.0%
Somewhat excessively drained0.0%
Well drained0.0%
Moderately well drained0.0%
Somewhat poorly drained0.0%
Poorly drained100.0%
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) 100%
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 0%
Hydrologic soil group across mapped Mexico acres. Scale 0 to 100% of mapped land.
Show as a table
Hydrologic soil group across mapped Mexico 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)100.0%
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 drained0.0%

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 Mexico (component kind "Series") in SSURGO: 744,330 acres.
Method
Shares are by mapped acres of Mexico components. The profile comes from the single largest Mexico component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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