LOCATION ULLOA AK
Established Series
Rev. RWG/WDL/JPM
02/2022
ULLOA SERIES
The Ulloa series consists of deep to calcareous bedrock, well drained soils formed in residuum and colluvium. These soils occur on sideslopes and ridges of hills; and mountainsides. Slopes range from 5 to 100 percent. Mean annual precipitation is 100 inches, and the mean annual temperature is 45 degrees F.
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive Typic Humicryods
TYPICAL PEDON: Ulloa silt loam--under forest vegetation (All colors are for moist soil).
Oi--4 to 3 inches; forest litter and living mosses.
Oe--3 to 0 inches; very dusky red (2.5YR 2/2) forest litter; many fine and medium, few coarse roots; extremely acid (pH 4.0); abrupt wavy boundary. (2 to 10 inches thick)
E--0 to 1 inch; grayish brown (10YR 5/2) silt loam; weak fine granular structure; friable, slightly sticky, slightly plastic; many black concretions 1 to 2 millimeters in diameter; 10 percent gravel; common fine, medium, and coarse roots; very strongly acid (pH 4.5); abrupt wavy boundary. (0 to 2 inches thick)
Bhs--1 to 3 inches; dark reddish brown (5YR 2.5/2) silt loam; weak fine granular structure; very friable, slightly sticky, slightly plastic; 10 percent gravel; few fine roots; many fine pores; very strongly acid (pH 4.5); clear wavy boundary. (1 to 3 inches thick)
Bs--3 to 24 inches; dark yellowish brown (10YR 3/4) gravelly silt loam; weak very fine subangular blocky structure; very friable, slightly sticky, slightly plastic; 30 percent gravel; many fine pores; medium acid (pH 6.0); abrupt wavy boundary. (10 to 28 inches thick)
BC--24 to 36 inches; very dark brown (10YR 2/2) gravelly silt loam; weak very fine subangular blocky structure; very friable, slightly sticky, slightly plastic; common patches of black (5YR 2.5/1), 30 percent gravel; few fine roots; many fine pores; neutral (pH 6.8); abrupt wavy boundary. (4 to 12 inches thick)
C--36 to 48 inches; dark yellowish brown (10YR 4/4) very gravelly loam; weak medium subangular blocky structure; friable, slightly sticky, slightly plastic; 40 percent gravel; many fine pores; neutral (pH 7.0); noneffervescent; abrupt irregular boundary.
R--48 inches; limestone bedrock.
TYPE LOCATION: Hollis Area, Alaska. 1.2 miles south of Klawock bridge on Klawock-Craig road, 120 yards east of road; SW 1/4, SE 1/4, Sec. 16, T 73 S, R.81 E, Copper River Meridian.
RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 38 to 42 degrees F. Thickness of the solum ranges from 17 to 45 inches. Organic carbon content of the upper 4 inches of the spodic horizon is greater than 6 percent. Depth to bedrock is greater than 40 inches. Coarse fragment content of the particle-size control section ranges from 15 to 30 percent. The mean annual soil temperature is 41 degrees F, and the mean summer soil temperature is 46 degrees F. Reaction increases with depth, ranging from extremely acid in the organic mat to neutral in the lower part of the mineral horizons..
The texture of the E horizon is sandy loam, loam or silt loam. Colors range in hue from 10YR to 5YR, value moist from 4 to 7, and chroma moist from 1 to 3. Coarse fragment content ranges from 10 to 15 percent.
The texture of the B horizons is loam or silt loam but ranges to include sandy loam. Coarse fragment content ranges from 5 to 30 percent gravel. Colors range in hue from 2.5YR to 10YR; value moist from 2 to 4, and chroma moist from 1 to 6.
COMPETING SERIES: These are the
Diobsud (WA),
Fordsterror (AK),
Gallup (WA),
Kulshan (WA),
Potchub (WA),
Tokeen (AK), and
Vixen (AK) series in the same family. Diobsud and Potchub soils have dense compact till within 40 inches of the mineral surface. Fordsterror, Kulshan, and Tokeen soils have bedrock within 40 inches of the mineral surface. Gallup and Vixen soils have pH less than 5.5 in the lower part of the control section.
GEOGRAPHIC SETTING: Ulloa soils occur on strongly sloping to very steep hillslopes, valleysides, and toeslopes of valleybottoms. The parent material is colluvium and residuum from limestone and marble. The climate is humid maritime with a mean annual precipitation of 100 inches. Mean annual air temperature is about 45 degrees F, and the mean summer air temperature is 55 degrees F. The slope gradient is commonly less than 60 percent, but ranges from 5 to 75 percent. Elevation ranges from sea level to 3000 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Karta, McGilvery,
Sarkar, and
Wadleigh soils. Karta and Wadleigh soils are formed from glacial till and are found on hillslopes and valleysides. McGilvery soils consist of forest litter resting directly on bedrock on hillslopes. Sarkar soils are shallow to calcareous bedrock.
DRAINAGE AND PERMEABILITY: Well drained. Moderate permeability. Slow runoff.
USE AND VEGETATION: Ulloa soils are used for timber production, watershed protection, wildlife habitat, and recreation. The overstory vegetation is dominantly western hemlock, western red cedar, and Sitka spruce. The understory vegetation is primarily blueberry and devil's club.
DISTRIBUTION AND EXTENT: Southeast Alaska. The series is extensive.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: WASILLA, ALASKA
SERIES ESTABLISHED: Hollis Area, Alaska, 1969.
REMARKS: Diagnostic horizons and features recognized in this soil are: a. albic horizon from 0 to 1 inch; a spodic horizon from 1 to 3 inches; more than 6 percent organic carbon in the upper 2 inches of the spodic horizon; coarse-loamy material from 10 to 40 inches. A cryic temperature regime is assumed. The Ulloa series formerly classified as thixotropic. That part of the spodic horizon that meets amorphous requirements does not extend more than 4 inches into the 10 to 40 inch control section. The particle size of the control section has a significant relation to the physical and chemical properties of the soil.
ADDITIONAL DATA: Limited laboratory data is available for this soil: Stand Density Plot pedon number 131.
National Cooperative Soil Survey
U.S.A.