LOCATION HALFMOON                AK

Established Series
SAS/TJR/SJN
05/2022

HALFMOON SERIES

The Halfmoon series consists of very deep, very poorly drained soils formed in organic material and alluvium on floodplains. Slopes range from 0 to 3 percent. The mean annual precipitation is about 610 millimeters and the mean annual air temperature is about 0.6 degrees C.

TAXONOMIC CLASS: Euic Fluvaquentic Cryohemists

TYPICAL PEDON: Halfmoon mucky peat, located on a floodplain on a plain with a slope of 1 percent and elevation of 9 meters; when described on September 18th, 2008 the soil was wet throughout (Colors are for moist soil unless otherwise noted)

Oe--0 to 45 cm; mucky peat; many fine roots, common medium roots, few coarse roots, and many very fine roots; slightly acid (pH 6.5); clear smooth boundary

C--45 to 55 cm; very dark grayish brown (2.5Y 3/2) silt loam; 37 percent sand; 55 percent silt; 8 percent clay; massive; friable, nonsticky, nonplastic; common fine roots, few medium roots, few coarse roots, and common very fine roots; moderately acid (pH 5.9); clear smooth boundary

Ab--55 to 65 cm; very dark grayish brown (10YR 3/2) mucky silt loam; 25 percent sand; 65 percent silt; 10 percent clay; weak fine subangular blocky structure; friable, nonsticky, nonplastic; common fine roots, few medium roots, few coarse roots, and common very fine roots; strongly acid (pH 5.5); clear smooth boundary

Oi--65 to 183 cm; peat; common fine roots, few medium roots, few coarse roots, and common very fine roots; slightly acid (pH 6.3)

TYPE LOCATION: Dillingham Census Area, Alaska; Located in the Village of Portage Creek; 58.904444 degrees north latitude and 157.723333 degrees west longitude.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 0.5 to 0.7 degrees C (cryic soil temperature regime)
Soil moisture control section - Soil is wet within 25 centimeters of the soil surface for much of the growing season in most years (aquic soil moisture regime)
Depth to aquic conditions - 0 cm

All mineral horizons-
Reaction - 5.5 to 5.9

Particle-size control section-
Clay content - 4 to 12 percent
Rock fragments - 0 percent

Oe horizon
Thickness - 35 to 45 cm

C horizon
Hue - 2.5Y
Value - 3
Chroma - 2
Fine earth texture - Silt loam
Clay content - 4 to 10 percent
Reaction - 5.9
Rock fragments - 0 percent
Thickness - 10 cm

Ab horizon
Hue - 10YR
Value - 3
Chroma - 2
Fine earth texture - Mucky silt loam
Clay content - 6 to 12 percent
Reaction - 5.5
Rock fragments - 0 percent
Thickness - 10 cm

Oi horizon
Thickness - 118 cm

COMPETING SERIES: These include the Icknuun soils. The Icknuun soils are till plain soils that do not flood

GEOGRAPHIC SETTING:
Parent material - Mossy organic material over coarse-loamy alluvium over mossy organic material
Landform - Flood plains
Slope - 0 to 1 percent
Elevation - 8 to 21 meters
Climate - Cool summers; cold winters, August and September are the wettest months
Mean annual precipitation - 608 to 612 mm
Mean annual air temperature - 0.5 to 0.7 degrees C
Frost free duration - 85 to 140 days

GEOGRAPHICALLY ASSOCIATED SOILS:
Nunachuak - Formed in grassy organic parent material over loamy and silty alluvium, flood plains
Lewispoint - Formed in coarse loamy alluvium, flood plains
Kokwok - Formed in organic material over loamy and sandy alluvium

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: (Ksat)
Drainage class - Very poorly drained
Saturation in normal years - At or near the soil surface
Flooding - Rare
Ponding - Frequent and very long
Ksat - Moderately high to high throughout organic soil material and moderately high in the mineral soil material

USE AND VEGETATION:
Use - Wildlife habitat
Potential natural vegetation - Western Alaska maritime dwarf scrubland composed of dwarf birch, sweetgale, marsh Labrador tea, bluejoint grass, sedges, purple marshlocks, and sphagnum moss

DISTRIBUTION AND EXTENT: Bristol Bay Lowlands; MLRA 236; small extent

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: WASILLA, ALASKA

SERIES ESTABLISHED: Nushagak-Mulchatna Watershed Soil Survey, Dillingham Census Area, Alaska, 2019

REMARKS:
Particle-size control section - 0 to 130 cm
Soil moisture regime - Aquic
Aquic soil conditions - 0 to 183 cm

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National Cooperative Soil Survey
U.S.A.