LOCATION KOCACHO                 AK

Established Series
JDP/BA/TJR
05/2022

KOCACHO SERIES

Landscape--alluvial plains
Landform--depressions on stream terraces
Slope--0 to 3 percent
Parent material--alluvium
Mean annual precipitation--about 255 mm
Mean annual air temperature--about -6 degrees C
Depth class--very deep
Drainage class--somewhat poorly drained
Soil moisture regime--udic
Soil temperature regime--cryic
Soil moisture subclass--aquic

TAXONOMIC CLASS: Sandy-skeletal, mixed Oxyaquic Cryorthents

TYPICAL PEDON: Kocacho gravelly silt loam on a woodland terrace with a slope of 0 percent and an elevation of 279 m (The soil was moist to a depth of 60 cm and wet below a depth of 60 cm when described on July 28, 2013.)

Oi--0 to 8 cm; slightly decomposed plant material; common very fine to coarse roots; moderately acid (pH 6.0); abrupt smooth boundary

A--8 to 12 cm; gravelly silt loam; yellowish brown (10YR 5/4) dry, dark yellowish brown (10YR 3/4) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine to very coarse roots; common fine and medium pores; 15 percent gravel; noneffervescent; strongly acid (pH 5.4); clear smooth boundary

AC--12 to 22 cm; very gravelly silt loam; very pale brown (10YR 7/4) dry, yellowish brown (10YR 5/4) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic; common fine and very fine roots; common fine and medium pores; 40 percent gravel; noneffervescent; moderately acid (pH 5.9); clear smooth boundary

C1--22 to 35 cm; extremely gravelly loamy sand; very pale brown (10YR 7/3) dry, brown (10YR 5/3) moist; massive; loose; common very fine roots; few fine and medium pores; 65 percent gravel; noneffervescent; neutral (pH 7.0); clear smooth boundary

C2--35 to 150 cm; extremely gravelly loamy sand; light brownish gray (10YR 6/2) dry, dark grayish brown (10YR 4/2) moist; massive; loose; common very fine roots; few fine and medium pores; 75 percent gravel; strongly effervescent; slightly alkaline (pH 7.8)

TYPE LOCATION: Yukon-Koyukuk Census Area, Alaska; latitude 67.3805560 degrees, longitude -144.1419170 degrees, datum WGS84 (coordinates determined with a GPS)

RANGE IN CHARACTERISTICS:
Mean annual soil temperature--0.5 to 2.5 degrees C
Rock fragment content--35 to 85 percent gravels and cobbles (by weighted average) in the zone from 25 to 100 cm

Oi horizon
Thickness--1 to 10 cm
Reaction--5.5 to 7.5

Oe horizon (where present)
Thickness--1 to 10 cm
Reaction--5.5 to 7.5

A and AC horizons
Value--2 to 5 moist, 4 to 7 dry
Chroma--2 to 4 moist
Fine-earth texture--silt loam, loam, very fine sandy loam, fine sandy loam, fine sand to coarse sand
Rock fragment content--5 to 50 percent total gravels
Clay content--0 to 18 percent
Reaction--5.0 to 7.5
Effervescence--none to slight
Combined thickness--5 to 15 cm

C1 and C2 horizons
Hue--10YR, 2.5Y
Value--3 to 5 moist, 5 to 7 dry
Chroma--1 to 3 moist
Fine-earth texture--fine sandy loam, loamy sand, sand to coarse sand
Rock fragment content--20 to 85 percent total gravels and cobbles
Clay content--0 to 10 percent
Reaction--6.0 to 8.0
Effervescence--none to strong
Combined thickness--125 to 145 cm

COMPETING SERIES:
Alsek----GLACIER BAY SURVEY ONGOING
Fingers----GLACIER BAY SURVEY ONGOING
Puffin----GLACIER BAY SURVEY ONGOING
Tangoe--these soils do not allow sandy textures in the surface horizons and are subject to flooding

GEOGRAPHIC SETTING:
Elevation--100 to 300 m
Climate--short, warm summers and long, very cold winters
Mean annual precipitation--210 to 310 mm
Mean annual air temperature-- -12 to 0 degrees C
Frost-free period--45 to 97 days

GEOGRAPHICALLY ASSOCIATED SOILS:
Venetie--dry longer than 90 days during the growing season; higher positions on similar landforms
Tlozhavun (gravelly taxadjuncts)--no aquic conditions within 150 cm; higher positions on similar landforms
Choonjik (gravelly taxadjuncts)-- no aquic conditions within 150 cm; calcareous; higher positions on similar landforms
Yasuda--aquic conditions within 25 cm with frequent ponding; depressions on similar landforms

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--somewhat poorly drained
Saturation in normal years--saturated between a depth of 25 to 50 cm in May through July, and between a depth of 50 to 75 cm in August and September; saturated below a depth of 100 cm throughout the rest of the year
Flooding--none
Ponding--none
Saturated hydraulic conductivity (Ksat)--high in the surface horizons and high or very high in the subsurface

USE AND VEGETATION:
Use--wildlife habitat, subsistence, recreation
Potential natural vegetation--black spruce, white spruce, quaking aspen, grayleaf willow, entireleaf mountain-avens, red fruit bearberry, lingonberry, bog Labrador tea, dwarf scouringrush, greygreen reindeer lichen, star reindeer lichen, stairstep moss, Tomentypnum moss, Aulacomnium moss

DISTRIBUTION AND EXTENT: Yukon Flats Lowlands, Alaska; MLRA 232; small extent

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

SERIES ESTABLISHED: Yukon Flats National Wildlife Refuge, Yukon-Koyukuk Census Area, Alaska; 2020

REMARKS:
Diagnostic horizons and other features in this pedon
*Particle-size control section--zone from 33 to 108 cm
*Ochric epipedon
Redoximorphic features are generally not visible in the coarse parent material; classified as a somewhat poorly drained soil due to observed water tables and as evidenced by wetland vegetation.
Combined A and AC horizons do not meet criteria for mollic epipedons after mixing the upper 18 cm of mineral soil.

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National Cooperative Soil Survey
U.S.A.