Soil series profile

Wiley soil series

Wiley is a well drained soil with a silt loam surface, mapped on 1,031,179 acres in 21 counties in CO. Hydrologic group B.

#169 by mapped area fine-silty Aridic Haplustalfs (Alfisols)

Drainage class: Well drained
Hydrologic group: B
Typical topsoil pH: 7.9
Mapped area: 1.0M

Typical Wiley 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 Wiley horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–4 in (Ap)	Silt loam	7.9	21%	11%	0.75%
4–10 in (Bt)	Silty clay loam	8.2	32%	6%	0.25%
10–29 in (Btk)	Silty clay loam	8.2	32%	6%	0.25%
29–41 in (Bk1)	Silty clay loam	8.2	30%	7%	0.25%
41–72 in (Bk2)	Silt loam	8.2	22%	11%	0.25%

Representative values from the most extensive Wiley map unit (Wiley silt loam, 0 to 3 percent slopes, survey area CO099). 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 Wiley soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Wiley soils is moderately alkaline: pH 7.9 (most land between 7.4 and 8.0). 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 Wiley acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silt loam (58% of mapped Wiley acres).

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

For lawns and yards

Most land is in hydrologic groups B and C, where rain soaks in at a moderate pace.

For a septic system

For conventional septic absorption fields, NRCS rates 41% of the acres in mapped Wiley soils very limited, 56% somewhat limited and 3% not limited.

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 Wiley soil is found

Mapped acres

Wiley is mapped in Colorado.

Counties with the most mapped Wiley soil
County	Acres	Share of county land
Baca County, CO	273,366	16.7%
Prowers County, CO	214,484	20.4%
Kiowa County, CO	131,969	11.5%
Cheyenne County, CO	129,120	11.3%
Las Animas County, CO	106,512	3.5%
Lincoln County, CO	51,380	3.1%
Adams County, CO	36,911	4.9%
Weld County, CO	21,639	0.8%
Huerfano County, CO	20,962	2.1%
Elbert County, CO	17,226	1.5%
Kit Carson County, CO	6,997	0.5%
El Paso County, CO	6,137	0.4%
Fremont County, CO	6,008	0.6%
Larimer County, CO	5,170	0.3%
Denver County, CO	1,354	1.3%
Pueblo County, CO	1,048	0.1%
Bent County, CO	410	0.0%
Boulder County, CO	319	0.1%
Morgan County, CO	46	0.0%
Arapahoe County, CO	23	0.0%
Broomfield County, CO	6	0.0%

Septic absorption fields

NRCS rating, share of Wiley acres

Not limited 3%

Somewhat limited 56%

Very limited 41%

Not rated <1%

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

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Septic tank absorption field rating across mapped Wiley acres.
Category	Share of acres
Not limited	3.0%
Somewhat limited	56.0%
Very limited	40.5%
Not rated	0.6%

Drainage, water table and flooding

Share of Wiley 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 1–4% (median 2%).
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 Wiley acres. Scale 0 to 100% of mapped land.

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Drainage class across mapped Wiley acres.
Category	Share of acres
Excessively drained	0.0%
Somewhat excessively drained	0.0%
Well drained	99.4%
Moderately well drained	0.0%
Somewhat poorly drained	0.0%
Poorly drained	0.0%
Very poorly drained	0.0%
Not rated	0.6%

Hydrologic soil group

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

B: moderate infiltration 53%

C: slow infiltration 47%

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 Wiley acres. Scale 0 to 100% of mapped land.

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Hydrologic soil group across mapped Wiley acres.
Category	Share of acres
A: fast infiltration (mostly sandy or gravelly)	0.0%
B: moderate infiltration	52.7%
C: slow infiltration	46.8%
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	0.6%

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 Wiley (component kind "Series") in SSURGO: 1,031,179 acres.
Method: Shares are by mapped acres of Wiley components. The profile comes from the single largest Wiley component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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