LOCATION FORT KNOX ME

Established Series
Rev. NRB-MGD-CIB
09/2018

FORT KNOX SERIES

The Fort Knox series consists of very deep, very poorly drained soils formed in herbaceous organic deposits over loamy mineral material. They are in tidal marshes subject to inundation by salt water twice daily. Slope ranges from 0 to 2 percent. Saturated hydraulic conductivity is moderately high or very high in the organic layers and low to high in the underlying mineral sediments. Mean annual temperature is about 7 degrees C and the mean annual precipitation is about 1900 mm.

TAXONOMIC CLASS: Loamy, mixed, euic, frigid Terric Sulfisaprists

TYPICAL PEDON: Fort Knox muck in a salt grass tidal marsh, undrained. (Colors are for moist soil unless noted otherwise.)

Oi--0 to 15 cm; dark brown (10YR 3/3) peat (fibric material); 55 percent fiber, 40 percent rubbed; dense mat of roots, stems and leaves; massive; common very fine roots; very friable; moderately alkaline in natural state; abrupt smooth boundary.

Oe--15 to 37 cm; very dark grayish brown (10YR 3/2) mucky peat (hemic material); 30 percent fiber, 20 percent rubbed; massive; common very fine roots; very friable; moderately alkaline in natural state; abrupt smooth boundary.

Oa--37 to 80 cm; black (2.5Y 2.5/1) muck (sapric material); 15 percent fiber, 5 percent rubbed; massive, common very fine roots; very friable, moderately alkaline in natural state; clear smooth boundary. (Combined thickness of the organic horizons is 40 to 130 cm thick with more than 50 percent sapric material.)

Ase--80 to 110 cm; very dark gray (2.5Y 3/1) mucky silt loam; massive; few very fine roots; very friable; slightly alkaline in natural state; abrupt smooth boundary. (0 to 70 cm thick)

Cseg1--110 to 130 cm; greenish gray (5GY 5/1) fine sandy loam; massive; friable; slightly alkaline in natural state.

Cseg2--130 to 165 cm; dark greenish gray (10GY 4/1) clay loam; massive; firm; slightly alkaline in natural state.

TYPE LOCATION: York County, Maine; town of Biddeford; on the campus of University of New England approximately 225 feet into the tidal marsh south southeast of a parking lot adjacent to the athletic fields (marsh is associated with Biddeford Pool); Biddeford USGS topographic quadrangle; latitude 43 degrees 27 minutes 24.1 seconds N., longitude 70 degrees 22 minutes 51.2 seconds W., WGS 84.

RANGE IN CHARACTERISTICS: Thickness of the organic deposits ranges from 40 to 130 cm. The soil is strongly acid to moderately alkaline in its natural condition and ultra-acid to neutral once oxidized. Mineral content (with varying textures from silty clay to sand) ranges from 5 to 50 percent throughout the organic portion of the profile. The electrical conductivity ranges from 0.6 to 4.5 dS/m in a 1:5 soil to water mixture by volume. Salt content ranges from about 5,000 to 35,000 ppm. The soil commonly is moderately saline in the surface tier and moderately saline to strongly saline in the subsurface and bottom tiers. In some places the range includes slightly saline.

The surface tier is neutral or has hue of 7.5YR to 5Y, value of 2 to 4 and chroma of 1 to 4. It is comprised of either hemic or fibric materials. Unrubbed fiber content is 35 to 100 percent; rubbed fiber content ranges from 20 to 85 percent.

The subsurface tier is neutral or has a hue of 7.5YR to 5Y, value of 2 to 4 and chroma of 1 to 4. It is comprised of either hemic or sapric materials. Unrubbed fiber content is 20 to 70 percent; rubbed fiber content is less than 40 percent.

The bottom tier, where present, is neutral or has hue of 7.5YR to 5Y, value of 2 to 3, and chroma of 1 to 3. It is comprised of dominantly sapric materials, but some pedons have hemic materials. Unrubbed fiber content is 10 to 50 percent; rubbed fiber content is less than 40 percent.

The A horizon, where present, is neutral or has a hue of 5YR to 5Y, value 2 to 3, and chroma of 1 to 3. Texture ranges from silt loam to loamy sand or their mucky modifiers. Clay content (by weight) is generally less than 18 percent. Some pedons have gravel and cobble sized fragments within this horizon ranging up to 5% (by volume).

The C horizon is neutral or has hue of 2.5Y to 10B, value of 2 to 6 and chroma of 0 to 2. Texture ranges from sand to silty clay loam. Some pedons have more than 35 percent clay (by weight) below 130 cm. Organic matter content ranges from less than 5 percent to 20 percent. Shell fragments and herbaceous fibers are common.

COMPETING SERIES: There are currently no other series in the same family. Westbrook soils are in a related family but occur in areas with a mesic soil temperature regime. Bestpitch and Pawcatuck soils are similar mesic soils in related families. Bestpitch soils are underlain by clayey materials with over 35 percent (by weight) in the fine-earth fraction. Pawcatuck soils are underlain by sandy materials within a depth of 40 to 130 cm.

GEOGRAPHIC SETTING: Fort Knox soils are level and occur in tidal marshes along the coast of Maine. They are subject to tidal flooding twice daily except in areas protected by dikes and tide gates. These soils developed in partially decomposed organic material from salt tolerate herbaceous plants over loamy sediments. Mean annual temperature is 5 to 9 degrees C and mean annual precipitation is 1600 to 2200 mm.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Damariscotta, Gouldsboro, Todds Point, Petit Manan, Phippsburg, and Pemaquid soils in nearby tidal marsh areas. Damariscotta soils are sandy mineral soils with a thin to absent organic cap less than 20 cm thick. Gouldsboro soils are fine-silty mineral soils with a thin to absent organic cap less than 20 cm thick. Todds Point soils have organic materials greater than 130 cm thick and seldom have any mineral soil within 165 cm. Petit Manan soils have organic materials 40 to 130 cm thick and are underlain by fine-silty mineral materials. Phippsburg soils have an organic cap 20 to 40 cm thick and are underlain by sandy mineral materials. Pemaquid soils have organic materials 40 cm to 130 cm thick and are underlain by sandy mineral materials.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Very poorly drained. Runoff is negligible or ponded. The soil is subject to very brief, very frequent tidal fluctuations. Saturated hydraulic conductivity is moderately high to very high.

USE AND VEGETATION: Most areas are in salt marsh and provide food and habitat for fish, shellfish and wildfowl. Small scattered areas are in saltgrass hay. The most common grasses are salt meadow grass, salt water grass and spike grass. Other vegetation includes blackgrass, sea lavender, saltwort, seaside goldenrod, aster, and purple gerardi. In areas where the 1:5 EC soil to water by volume is below 1.5 dS/m, vegetation consists principally of tall reeds and sedges.

DISTRIBUTION AND EXTENT: Coastal areas and along tidally influenced rivers of Maine; MLRA 144B. The series is of small extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Amherst, Massachusetts

SERIES ESTABLISHED: York County, Maine, 2018.

REMARKS: These soils were formerly mapped as Tidal marsh and/or Sulfihemists.

Diagnostic features and characteristics recognized in this pedon include:
1. Fibric materials - the zone from 0 to 15 cm (Oi horizon)
2. Hemic materials - the zone from 15 to 37 cm (Oe horizon).
3. Sapric materials - the zone from 37 to 80 cm (Oa horizon).
4. Sulfisaprists - sulfidic materials within 100 cm of the surface.
5. Loamy particle size class - mineral layers of silt loam, fine sandy loam, and clay loam 85 cm thick with a portion within the control section - from 80 cm to 130 cm (Ase and Cseg1 horizons).
5. Reaction (pH value) is more than 4.5 throughout the control section.

ADDITIONAL DATA: This pedon is entered as S2018ME031002 in the National Soils Information System.

National Cooperative Soil Survey
U.S.A.