LOCATION TASTA AK

Established Series
SDB/MJS
08/2025

TASTA SERIES

Depth class: very deep
Drainage class: well drained
Parent material: organic material over silty loess over sandy and gravelly colluvium
Landscape: mountains and foothills
Landform: mountain slopes and hillslopes
Slope: 10 to 80 percent
Mean annual precipitation: about 600 mm (24 in)
Mean annual air temperature: about -3 degrees C (27 degrees F)
Frost-free period: 32 to 89 days

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, nonacid, subgelic Pachic Haplogelolls

TYPICAL PEDON: Tasta gravelly silt loam in an alder community on a west facing convex, linear backslope on a slope of 73 percent at an elevation of 1195m (3921 ft)

Oi--0 to 5 cm (0 to 2 in); slightly decomposed plant material, black (7.5YR 2.5/1) rubbed moist; nonsticky, nonplastic; many very fine roots and few medium roots throughout and many fine roots throughout; 0 percent by volume; neutral (pH 6.9); clear smooth boundary (4 to 15 cm, 2 to 6 in)

A--5 to 12 cm (2 to 5 in); gravelly silt loam, black (10YR 2/1) broken face moist; weak fine granular structure; slightly hard, friable, nonsticky, slightly plastic; nonsmeary; common very fine and fine roots throughout; very fine and fine dendritic tubular pores; 18 percent subangular gravel by volume; neutral (pH 6.8); clear smooth boundary (6 to 14 cm, 2 to 6 in)

Bw--12 to 46 cm (5 to 18 in); extremely gravelly silt loam, very dark grayish brown (10YR 3/2) broken face moist; weak medium subangular blocky structure; slightly hard, friable, nonsticky, slightly plastic; nonsmeary; few very fine and fine roots throughout; very fine dendritic tubular pores; 78 percent subangular gravel by volume; neutral (pH 7.1); clear smooth boundary (31 to 40 cm, 12 to 16 in)

C--46 to 150 cm (18 to 59 in); extremely gravelly sandy loam, dark brown (10YR 3/3) broken face moist; massive; slightly hard, friable, nonsticky, slightly plastic; nonsmeary; few very fine roots top of horizon; fine interstitial pores; 2 percent medium dark yellowish brown (10YR 4/6), moist; 78 percent subangular gravel by volume; neutral (pH 6.9). (81 to 105 cm, 32 to 41 in)

TYPE LOCATION: North Copper River Soil Survey Area, Alaska; latitude 63.04019, longitude -144.16684, UTM 6993225.14 north and UTM 643275.24 east, zone 6, Datum WGS84.

RANGE IN CHARACTERISTICS:

Soil moisture regime: udic
Soil temperature regime: gelic
Mean annual soil temperature: -1 to 5 degrees C. (30 to 41 degrees F)
Thickness of organic material: 0 to 5 cm (0 to 2 in)
Thickness of mollic epipedon: 37 to 54 cm (15 to 21 in)

Oi, Oe, Oa horizons:
Hue: 7.5YR or 10YR
Value: 2 to 3
Chroma: 1 to 3
Texture: slightly decomposed organic material, moderately decomposed organic material, highly decomposed organic material
Organic matter: 60 to 90 percent
Reaction class: neutral (pH 6.6 to 7.3)

A horizon:
Hue: 7.5YR or 10YR
Value: 2 to 3
Chroma: 1 to 3
Texture: loam, silt loam, gravelly silt loam, very gravelly silt loam
Sand: 24 to 47 percent
Silt: 47 to 70 percent
Clay: 6 to 12 percent
Rock fragments: 0 to 45 percent gravel
Organic matter: 4 to 7 percent
Reaction class: neutral (pH 6.6 to 7.3)

Bw horizon:
Hue: 10YR or 2.5Y
Value: 3 to 4
Chroma: 2 to 3
Texture: gravelly loam, very gravelly silt loam, gravelly sandy loam, extremely gravelly silt loam
Sand: 24 to 57 percent
Silt: 37 to 70 percent
Clay: 6 to 11 percent
Rock fragments: 15 to 85 percent
Gravels: 15 to 80 percent
Cobbles: 0 to 5 percent
Organic matter: 1.5 to 4 percent
Reaction class: neutral (pH 6.6 to 7.3)

C horizon:
Hue: 10YR or 2.5Y
Value: 3 to 4
Chroma: 2 to 3
Texture: very gravelly sandy loam, very gravelly loam, extremely gravelly sandy loam
Sand: 45 to 68 percent
Silt: 22 to 45 percent
Clay: 2 to 10 percent
Rock fragments: 40 to 80 percent gravel
Organic matter: 0.5 to 1 percent
Reaction class: neutral (pH 6.6 to 7.3)

Some pedons have a paralithic contact at depths greater than 60 cm ( in).

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING:
Elevation: 800 to 1600 meters (2625 to 5250 ft)
Parent material: organic material over silty loess over sandy and gravelly colluvium
Landform: mountain slopes
Slopes: 10 to 80 percent
Mean annual precipitation: 300 to 1400 mm (12 to 55 in)
Mean annual air temperature: -5 to -1 degrees C. (23 to 30 degrees F)
Frost-free period: 32 to 89 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bartell, Centuu, Cirquecreek, Hungryhollow, Ironcreek, Klute, and Townlake soils.
Bartell are poorly drained, have a histic epipedon, and occur on drainage ways and stream terraces.
Centuu soils lack a gravelly modifier in the A horizons and occur on river valleys and alluvial fans with slopes under 20%.
Cirquecreek soils have a cambic horizon and occur on saddles and mountain slopes
Hungryhollow soils are poorly drained permafrost soils, have a sapric horizon, have mineral soil starting between 52 and 73 cm (21 and 29 in) deep, and occur on depressions in interior valleys.
Ironcreek soils are well drained, and occur in river valleys and flood plains.
Klute soils are moderately well drained or well drained, have stratified materials in the C horizons, and occur on low stream terraces and floodplains.
Townlake soils are moderately well drained, have permafrost, have folistic and mollic epipedons, have cryoturbation, and occur on hills, mountain slopes, and river valleys.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: well
Saturated Hydraulic Conductivity: very high in the Oi horizon, moderately high in the A and Bw horizons, high in the C horizon.
Permeability: very rapid in the Oi horizon, moderate in the A and Bw horizons, moderately rapid in the C horizon.
Runoff: high

USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: mountain alder

DISTRIBUTION AND EXTENT: MLRA 228 Interior Alaska mountains.
Extent: extensive

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Wasilla, Alaska

SERIES ESTABLISHED: North Copper River Soil Survey, Alaska, 2024.

REMARKS: Diagnostic features and horizons recognized in this profile include:

Particle-size control section: 30 to 105 cm (12 to 41 in)

Mollic epipedon: 5 to 46 cm (2 to 18 in) (A and Bw horizons)

ADDITIONAL DATA:

User pedon Id: 2023AK261124

National Cooperative Soil Survey
U.S.A.