Soil series profile

Phillips soil series

Phillips is a well drained soil with a loam surface, mapped on 1,195,400 acres in 8 counties in MT. Hydrologic group C.

#128 by mapped area fine Aridic Haplustalfs (Alfisols)

Drainage class: Well drained
Hydrologic group: C
Typical topsoil pH: 6.8
Mapped area: 1.2M

Typical Phillips 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 Phillips horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–2 in (A)	Loam	6.8	22%	41%	2%
2–7 in (E)	Loam	6.6	19%	43%	1.5%
7–11 in (Bt)	Clay	7.4	41%	29%	1%
11–15 in (Btk)	Clay loam	8.0	39%	30%	1%
15–36 in (Bk)	Clay loam	8.5	36%	33%	0.75%
36–50 in (BCyz)	Clay loam	8.0	33%	34%	0.5%
50–79 in (Cz)	Clay loam	7.8	33%	34%	0.5%

Representative values from the most extensive Phillips map unit (Phillips-Elloam complex, 0 to 4 percent slopes, survey area MT608). 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 Phillips soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Phillips soils is neutral: pH 6.8 (most land between 6.7 and 6.8), the range most vegetables, flowers and lawn grasses prefer.

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

100% of mapped Phillips 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 100% of the acres in mapped Phillips 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 Phillips soil is found

Mapped acres

Phillips is mapped in Montana.

Counties with the most mapped Phillips soil
County	Acres	Share of county land
Phillips County, MT	386,582	10.4%
Valley County, MT	379,952	11.8%
Blaine County, MT	208,187	7.6%
Hill County, MT	118,419	6.4%
Chouteau County, MT	42,877	1.7%
Toole County, MT	30,900	2.9%
Liberty County, MT	20,887	2.3%
Roosevelt County, MT	7,596	0.5%

Septic absorption fields

NRCS rating, share of Phillips acres

Not limited 0%

Somewhat limited 0%

Very limited 100%

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

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Septic tank absorption field rating across mapped Phillips acres.
Category	Share of acres
Not limited	0.0%
Somewhat limited	0.0%
Very limited	100.0%

Drainage, water table and flooding

Share of Phillips 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 2–5% (median 2%).
Topsoil organic matter: Median 2%.

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

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

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Hydrologic soil group across mapped Phillips 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 Phillips (component kind "Series") in SSURGO: 1,195,400 acres.
Method: Shares are by mapped acres of Phillips components. The profile comes from the single largest Phillips component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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