Soil series profile

Witt soil series

Witt is a well drained soil with a loam surface, mapped on 327,774 acres in 6 counties across 2 states. Hydrologic group C.

#1005 by mapped area fine-silty Ustollic Haplargids (Aridisols)

Drainage class: Well drained
Hydrologic group: C
Typical topsoil pH: 7.5
Mapped area: 328k

Typical Witt 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 Witt horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–4 in (H1)	Loam	7.5	18%	41%	0.8%
4–38 in (H2)	Clay loam	7.5	28%	27%	0.25%
38–60 in (H3)	Loam	8.2	23%	33%	0.25%

Representative values from the most extensive Witt map unit (Witt loam, 1 to 6 percent slopes, survey area NM674). 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 Witt soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Witt soils is slightly alkaline: pH 7.5. Acid-loving plants such as blueberries and azaleas struggle without amended beds, and some trees and shrubs show iron chlorosis (yellow leaves with green veins).

Loamy topsoil (loam, silt loam and similar) covers >99% of mapped Witt acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is loam (71% of mapped Witt acres).

>99% of mapped Witt acres is moderately well to excessively drained, which suits most garden plants.

For lawns and yards

On 88% 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 89% of the acres in mapped Witt soils very limited, 11% 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 Witt soil is found

Mapped acres

Witt is mapped in New Mexico and Colorado.

Counties with the most mapped Witt soil
County	Acres	Share of county land
Torrance County, NM	162,859	7.6%
La Plata County, CO	52,097	5.0%
Lincoln County, NM	38,078	1.4%
Santa Fe County, NM	25,921	2.6%
Sandoval County, NM	23,851	1.2%
Bernalillo County, NM	16,952	2.3%

Septic absorption fields

NRCS rating, share of Witt acres

Not limited 0%

Somewhat limited 11%

Very limited 89%

Not rated <1%

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

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Septic tank absorption field rating across mapped Witt acres.
Category	Share of acres
Not limited	0.0%
Somewhat limited	11.2%
Very limited	88.6%
Not rated	0.1%

Drainage, water table and flooding

Share of Witt acres

Depth to seasonal high water table: None reported within about 6.5 feet (median where reported).
Flooding: Not mapped as flooding on most acres.
Slope: Typically 1–6% (median 4%).
Topsoil organic matter: Median 0.8%.

Drainage class

Excessively drained 0%

Somewhat excessively drained 0%

Well drained >99%

Moderately well drained 0%

Somewhat poorly drained 0%

Poorly drained 0%

Very poorly drained 0%

Not rated <1%

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

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Drainage class across mapped Witt acres.
Category	Share of acres
Excessively drained	0.0%
Somewhat excessively drained	0.0%
Well drained	99.9%
Moderately well drained	0.0%
Somewhat poorly drained	0.0%
Poorly drained	0.0%
Very poorly drained	0.0%
Not rated	0.1%

Hydrologic soil group

A: fast infiltration (mostly sandy or gravelly) 0%

B: moderate infiltration 12%

C: slow infiltration 88%

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 0%

Not rated <1%

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

Show as a table

Hydrologic soil group across mapped Witt acres.
Category	Share of acres
A: fast infiltration (mostly sandy or gravelly)	0.0%
B: moderate infiltration	11.8%
C: slow infiltration	88.0%
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	0.0%
Not rated	0.1%

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 Witt (component kind "Series") in SSURGO: 327,774 acres.
Method: Shares are by mapped acres of Witt components. The profile comes from the single largest Witt component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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