Soil series profile
Graycalm soil series
Graycalm is a somewhat excessively drained soil with a sand surface, mapped on 733,526 acres in 32 counties across 3 states. Hydrologic group A.
- Drainage class
- Somewhat excessively drained >99% of mapped acres
- Hydrologic group
- A >99% of mapped acres
- Typical topsoil pH
- 4.1 extremely acidic · range 4.1–5.5
- Mapped area
- 734k acres in 32 counties, 3 states
Typical Graycalm profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–3 in (A) | Sand | 4.1 | 4% | 88% | 5.69% |
| 3–35 in (Bw) | Sand | 4.6 | 3% | 88% | 0.59% |
| 35–80 in (E and Bt) | Sand | 5.3 | 3% | 93% | 0.32% |
What this means
What Graycalm soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Graycalm soils is extremely acidic: pH 4.1 (most land between 4.1 and 5.5). 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.
Sandy topsoil covers >99% of mapped Graycalm acres. It drains fast and warms early in spring, but dries out and loses nutrients quickly: mulch, compost and steady watering help. The most common surface texture is sand (82% of mapped Graycalm acres).
>99% of mapped Graycalm acres is excessively or somewhat excessively drained: water moves through fast, so gardens need more frequent watering in dry spells.
For lawns and yards
>99% of mapped acres is in hydrologic group A, where water soaks in fast. Lawns there dry out quickly; deeper, less frequent watering and organic matter help.
For a septic system
For conventional septic absorption fields, NRCS rates >99% of the acres in mapped Graycalm 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.
Where Graycalm soil is found
Mapped acres
Graycalm is mapped in Michigan, Wisconsin and Minnesota.
| County | Acres | Share of county land |
|---|---|---|
| Oscoda County, MI | 106,546 | 29.5% |
| Crawford County, MI | 88,432 | 24.8% |
| Roscommon County, MI | 73,642 | 22.0% |
| Clare County, MI | 65,200 | 18.1% |
| Ogemaw County, MI | 54,895 | 15.3% |
| Montmorency County, MI | 45,938 | 13.1% |
| Burnett County, WI | 43,323 | 8.3% |
| Washburn County, WI | 34,723 | 6.8% |
| Missaukee County, MI | 34,400 | 9.5% |
| Wexford County, MI | 28,671 | 7.9% |
| Lake County, MI | 26,944 | 7.4% |
| St. Louis County, MN | 21,436 | 0.5% |
| Alcona County, MI | 20,826 | 4.8% |
| Kalkaska County, MI | 16,372 | 4.6% |
| Iosco County, MI | 13,711 | 3.9% |
| Otsego County, MI | 12,601 | 3.8% |
| Presque Isle County, MI | 10,051 | 2.4% |
| Becker County, MN | 6,388 | 0.8% |
| Marathon County, WI | 4,647 | 0.5% |
| Douglas County, WI | 4,607 | 0.6% |
| Cass County, MN | 3,960 | 0.3% |
| Alpena County, MI | 3,032 | 0.8% |
| Rusk County, WI | 2,947 | 0.5% |
| Polk County, WI | 2,338 | 0.4% |
| Kanabec County, MN | 2,003 | 0.6% |
| Sawyer County, WI | 1,591 | 0.2% |
| Mille Lacs County, MN | 1,273 | 0.3% |
| Itasca County, MN | 1,244 | 0.1% |
| Gladwin County, MI | 621 | 0.2% |
| Koochiching County, MN | 597 | 0.0% |
| Lake County, MN | 566 | 0.0% |
| Isabella County, MI | 1 | 0.0% |
Septic absorption fields
NRCS rating, share of Graycalm acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.0% |
| Somewhat limited | 0.0% |
| Very limited | 99.5% |
| Not rated | 0.5% |
Drainage, water table and flooding
Share of Graycalm 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 2–21% (median 3%).
- Topsoil organic matter
- Median 2.8%.
Drainage class
Show as a table
| Category | Share of acres |
|---|---|
| Excessively drained | 0.0% |
| Somewhat excessively drained | 99.2% |
| Well drained | 0.0% |
| Moderately well drained | 0.3% |
| Somewhat poorly drained | 0.0% |
| Poorly drained | 0.0% |
| Very poorly drained | 0.0% |
| Not rated | 0.5% |
Hydrologic soil group
Show as a table
| Category | Share of acres |
|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 99.5% |
| 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 | 0.0% |
| Not rated | 0.5% |
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 Graycalm (component kind "Series") in SSURGO: 733,526 acres.
- Method
- Shares are by mapped acres of Graycalm components. The profile comes from the single largest Graycalm component. Full methodology.