Soil series profile

Platner soil series

Platner is a well drained soil with a loam surface, mapped on 653,943 acres in 17 counties in CO. Hydrologic group C.

#375 by mapped area fine Aridic Paleustolls (Mollisols)

Drainage class: Well drained
Hydrologic group: C
Typical topsoil pH: 7.2
Mapped area: 654k

Typical Platner 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 Platner horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–6 in (Ap)	Loam	7.2	19%	43%	1.5%
6–11 in (Bt1)	Clay	7.6	40%	30%	1.5%
11–20 in (Bt2)	Clay	7.6	40%	30%	1.5%
20–27 in (Bk1)	Loam	8.2	27%	37%	0.75%
27–37 in (Bk2)	Sandy clay loam	8.5	20%	61%	0.5%
37–80 in (C)	Sandy clay loam	8.5	20%	61%	0.5%

Representative values from the most extensive Platner map unit (Platner loam, 0 to 3 percent slopes, survey area CO121). 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 Platner soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Platner soils is neutral: pH 7.2 (most land between 7.0 and 7.2), the range most vegetables, flowers and lawn grasses prefer.

Loamy topsoil (loam, silt loam and similar) covers 100% of mapped Platner acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is loam (92% of mapped Platner acres).

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

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.

For a septic system

For conventional septic absorption fields, NRCS rates 17% of the acres in mapped Platner soils very limited, 83% somewhat limited and 0% 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 Platner soil is found

Mapped acres

Platner is mapped in Colorado.

Counties with the most mapped Platner soil
County	Acres	Share of county land
Washington County, CO	153,939	9.5%
Logan County, CO	92,001	7.8%
Weld County, CO	90,510	3.5%
Lincoln County, CO	75,872	4.6%
Phillips County, CO	68,685	16.3%
Yuma County, CO	43,281	2.9%
Adams County, CO	42,146	5.5%
Elbert County, CO	36,918	3.2%
Kit Carson County, CO	18,302	1.3%
Morgan County, CO	16,571	2.1%
Broomfield County, CO	6,755	23.7%
Denver County, CO	5,228	5.2%
Douglas County, CO	2,890	0.5%
Jefferson County, CO	637	0.2%
Boulder County, CO	96	0.0%
Larimer County, CO	62	0.0%
Cheyenne County, CO	50	0.0%

Septic absorption fields

NRCS rating, share of Platner acres

Not limited 0%

Somewhat limited 83%

Very limited 17%

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

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Septic tank absorption field rating across mapped Platner acres.
Category	Share of acres
Not limited	0.0%
Somewhat limited	83.2%
Very limited	16.8%

Drainage, water table and flooding

Share of Platner 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 2–4% (median 2%).
Topsoil organic matter: Median 1.5%.

Drainage class

Excessively drained 0%

Somewhat excessively drained 0%

Well drained 100%

Moderately well drained 0%

Somewhat poorly drained 0%

Poorly drained 0%

Very poorly drained 0%

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

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Drainage class across mapped Platner acres.
Category	Share of acres
Excessively drained	0.0%
Somewhat excessively drained	0.0%
Well drained	100.0%
Moderately well drained	0.0%
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 100%

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%

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

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Hydrologic soil group across mapped Platner acres.
Category	Share of acres
A: fast infiltration (mostly sandy or gravelly)	0.0%
B: moderate infiltration	0.0%
C: slow infiltration	100.0%
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%

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 Platner (component kind "Series") in SSURGO: 653,943 acres.
Method: Shares are by mapped acres of Platner components. The profile comes from the single largest Platner component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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