LOCATION KOKWOK                  AK

Established Series
SAS/TJR/SJN
05/2022

KOKWOK SERIES

The Kokwok series consists of very deep, well drained soils formed in loamy, sandy, and gravelly alluvium on flood plains. Slopes are 0 to 3 percent. The mean annual precipitation is about 670 millimeters and the mean annual air temperature is about 0.6 degrees C.

TAXONOMIC CLASS: Coarse-loamy over sandy or sandy-skeletal, isotic over mixed Typic Dystrocryepts

TYPICAL PEDON: Kokwok silt loam, located on a flood plain with a slope of 1 percent and elevation of 15 meters; when described on September 16th, 2008 the soil was moist throughout (Colors are for moist soil unless otherwise noted)

Oi--0 to 10 cm; slightly decomposed plant material; common fine roots, common medium roots, common coarse roots, and many very fine roots; very strongly acid (pH 4.9); clear smooth boundary

AB--10 to 16 cm; 50 percent black (7.5YR 2.5/1) and 50 percent dark brown (7.5YR 3/3) silt loam; 30 percent sand; 65 percent silt; 5 percent clay; weak fine granular structure; friable, nonsticky, nonplastic; common fine roots, common medium roots, common coarse roots, and many very fine roots; very strongly acid (pH 4.9); clear smooth boundary

Bw--16 to 100 cm; 50 percent brown (7.5YR 4/2) and 50 percent strong brown (7.5YR 4/6) silt loam; 40 percent sand; 55 percent silt; 5 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 5.4); clear smooth boundary

2C--100 to 183 cm; dark yellowish brown (10YR 4/4) fine sand; 90 percent sand; 8 percent silt; 2 percent clay; massive; very friable, nonsticky, nonplastic; few fine roots, few medium roots, few coarse roots, and few very fine roots; moderately acid (pH 5.9)

TYPE LOCATION: Dillingham Census Area, Alaska; 4 kilometers northeast of the Village of Portage Creek; 58.9394444 degrees north latitude and 157.6819444 degrees west longitude.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 0.9 to 2.5 degrees C (cryic soil temperature regime)
Soil moisture control section - Dry less than 45 consecutive days from June to October (udic soil moisture regime)
Thickness of cambic horizon - 24 to 84 cm

All mineral horizons-
Reaction - 4.5 to 5.9

Particle-size control section-
Clay content - 0 to 7 percent
Rock fragments - 0 to 85 percent

Oi horizon
Thickness - 4 to 10 cm
Reaction - 3.9 to 4.9

AB or A horizon
Hue - 7.5YR or 10YR
Value - 2.5 to 4
Chroma - 1 to 3
Fine earth texture - Silt loam or silt
Clay content - 4 to 8 percent
Reaction - 4.5 to 5.3
Rock fragments - 0 percent
Thickness - 6 to 16 cm

Bw horizon
Hue - 10YR or 7.5YR
Value - 4
Chroma - 2 to 6
Fine earth texture - Silt loam, silt, stratified silt loam, or very fine sandy loam
Clay content - 3 to 7 percent
Reaction - 4.7 to 5.8
Rock fragments - 0 percent
Thickness - 17 to 84 cm

2C horizon
Hue - 10YR
Value - 4
Chroma - 2 or 4
Fine earth texture - Fine sand, coarse sand, or sand
Clay content - 0 to 5 percent
Reaction - 5.1 to 5.9
Rock fragments - 0 to 85 percent rounded gravels
Thickness - 159 to 163 cm

COMPETING SERIES: These are the Tunravik soils. Tunravik soils are found on terraces and do not flood or pond.

GEOGRAPHIC SETTING:
Parent material - Organic material over coarse-loamy alluvium over sandy and gravelly alluvium
Landform - Flood plains
Slope - 0 to 1 percent
Elevation - 12 to 55 meters
Climate - Cool summers; cold winters, August and September are the wettest months
Mean annual precipitation - 608 to 771 mm
Mean annual air temperature - 0.3 to 0.7 degrees C
Frost free duration - 85 to 140 days

GEOGRAPHICALLY ASSOCIATED SOILS:
Iowithla - Moderately well drained, sandy or sandy-skeletal, and similar landform
Lewispoint - Moderately well drained, coarse loamy, loamy alluvium, similar landform
Nunachuak - Very poorly drained, silty and loamy alluvium, low flood plains
Halfmoon - Very poorly drained, formed in organic parent material, low flood plains
Orgter - Very poorly drained, formed in organic parent material, stream terraces
Ekvik - Well drained, formed in colluvium and glacial outwash, bluffs

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: (Ksat)
Drainage class - Well drained
Saturation in normal years - None
Flooding - Rare
Ponding - Rare
Ksat - Moderately high to high in the loamy alluvium and high to very high in the sandy and gravelly alluvium

USE AND VEGETATION:
Use - Wildlife habitat and community development
Potential natural vegetation - Western maritime forest composed of Paper birch, white spruce, Kenai birch, bluejoint grass, horsetails, spreading woodfern, alder, spirea, highbush cranberry, and 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 - 35 to 110 cm
Soil moisture regime - Udic
Ochric epipedon
Cambic horizon - Bw horizon

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National Cooperative Soil Survey
U.S.A.