Soil series profile

Tangi soil series

Tangi is a moderately well drained soil with a silt loam surface, mapped on 257,897 acres in 9 counties across 2 states. Hydrologic group C/D.

#1353 by mapped area fine-silty Typic Fragiudults (Ultisols)

Drainage class: Moderately well drained
Hydrologic group: C/D
Typical topsoil pH: 5.3
Mapped area: 258k

Typical Tangi profile

Texture and pH by depth

Depth to scale. More strongly shaded layers hold more clay. Horizon names are the soil survey's (A = topsoil, B = subsoil, C = parent material).

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Typical Tangi horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–4 in (Ap)	Silt loam	5.3	7%	22%	2.25%
4–25 in (Bt)	Silt loam	5.3	24%	7%	0.25%
25–48 in (2Btx1)	Clay loam	5.3	28%	27%	0.25%
48–65 in (2Btx2)	Clay	5.3	45%	26%	0.25%

Representative values from the most extensive Tangi map unit (Tangi silt loam, 3 to 8 percent slopes, survey area LA037). Other map units of this series vary within the series range.

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

What this means

What Tangi soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Tangi soils is strongly acidic: pH 5.3. Most vegetables and lawn grasses do best around 6.0 to 7.0, so lime is often needed; blueberries, azaleas and rhododendrons like it as it is.

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

100% of mapped Tangi acres is moderately well to excessively drained, which suits most garden plants.

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.

For a septic system

For conventional septic absorption fields, NRCS rates >99% of the acres in mapped Tangi 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 Tangi soil is found

Mapped acres

Tangi is mapped in Louisiana and Mississippi.

Counties with the most mapped Tangi soil
County	Acres	Share of county land
East Feliciana Parish, LA	93,149	32.3%
Tangipahoa Parish, LA	80,510	16.1%
St. Helena Parish, LA	68,487	26.1%
Washington Parish, LA	9,455	2.2%
West Feliciana Parish, LA	5,467	2.1%
East Baton Rouge Parish, LA	581	0.2%
Livingston Parish, LA	185	0.0%
St. Tammany Parish, LA	34	0.0%
Stone County, MS	29	0.0%

Septic absorption fields

NRCS rating, share of Tangi acres

Not limited 0%

Somewhat limited 0%

Very limited >99%

Not rated <1%

Septic tank absorption field rating across mapped Tangi acres. Scale 0 to 100% of mapped land.

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Septic tank absorption field rating across mapped Tangi acres.
Category	Share of acres
Not limited	0.0%
Somewhat limited	0.0%
Very limited	99.2%
Not rated	0.8%

Drainage, water table and flooding

Share of Tangi acres

Depth to seasonal high water table: About 1.7 feet (20 in) (median where reported).
Flooding: Not mapped as flooding on most acres.
Slope: Typically 2–6% (median 6%).
Topsoil organic matter: Median 2.2%.

Drainage class

Excessively drained 0%

Somewhat excessively drained 0%

Well drained 0%

Moderately well drained 100%

Somewhat poorly drained 0%

Poorly drained 0%

Very poorly drained 0%

Drainage class across mapped Tangi acres. Scale 0 to 100% of mapped land.

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Drainage class across mapped Tangi acres.
Category	Share of acres
Excessively drained	0.0%
Somewhat excessively drained	0.0%
Well drained	0.0%
Moderately well drained	100.0%
Somewhat poorly drained	0.0%
Poorly drained	0.0%
Very poorly drained	0.0%

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) 0%

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 >99%

Not rated <1%

Hydrologic soil group across mapped Tangi acres. Scale 0 to 100% of mapped land.

Show as a table

Hydrologic soil group across mapped Tangi acres.
Category	Share of acres
A: fast infiltration (mostly sandy or gravelly)	0.0%
B: moderate infiltration	0.0%
C: slow infiltration	0.0%
D: very slow infiltration (clayey, shallow or wet)	0.0%
A/D: D as is, A if drained	0.0%
B/D: D as is, B if drained	0.0%
C/D: D as is, C if drained	99.2%
Not rated	0.8%

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 Tangi (component kind "Series") in SSURGO: 257,897 acres.
Method: Shares are by mapped acres of Tangi components. The profile comes from the single largest Tangi component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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