LOCATION PSUNI OR
Tentative Series
SERIES PROPOSED CSW/KMS
06/2016
PSUNI SERIES
Landscape--foothills
Landform--flood plains, overflow stream channels
Slope--0 to 5 percent
Parent material--alluvium derived from basalt
Mean annual precipitation--about 740 mm
Depth class--very deep
Drainage class--somewhat poorly drained, moderately well drained
Soil moisture regime--xeric
Soil temperature regime--mesic
Soil moisture subclass--oxyaquic
TAXONOMIC CLASS: Sandy-skeletal, mixed, mesic Oxyaquic Haploxerolls
TYPICAL PEDON: Psuni gravelly loam in a lotic riparian area, on a southeast-facing, 1-percent slope at an elevation of 570 m
Oi--0 to 1 cm; slightly decomposed plant material; abrupt smooth boundary
A1--1 to 8 cm; gravelly loam, very dark brown (10YR 2/2) dry, black (10YR 2/1) moist; strong medium granular structure; very friable, slightly hard, slightly sticky and moderately plastic; common very coarse, coarse, medium, and fine and many very fine roots; common fine and very fine tubular pores; 20 percent rounded basalt gravel; negative reaction to alpha-alpha dipyridyl; noneffervescent; neutral (pH 7.2); clear smooth boundary
A2--8 to 33 cm; gravelly loam, very dark grayish brown (10YR 3/2) dry, black (10YR 2/1) moist; strong fine granular structure; friable, slightly hard, slightly sticky and moderately plastic; common very coarse, medium, and fine and many very fine roots; many very fine tubular pores; 20 percent rounded basalt gravel; negative reaction to alpha-alpha dipyridyl; noneffervescent; neutral (pH 7.2); clear smooth boundary
C1--33 to 74 cm; very gravelly loamy coarse sand, very dark grayish brown (10YR 3/2) dry, black (10YR 2/1) moist; single grain; loose, nonsticky and nonplastic; common very coarse, coarse, medium, fine, and very fine roots; interstitial pores; prominent masses of oxidized iron around rock fragments, yellowish red (5YR 4/6) moist; 10 percent rounded basalt cobbles and 45 percent basalt gravel, 5 percent of each coated with masses of oxidized iron; negative reaction to alpha-alpha dipyridyl; noneffervescent; neutral (pH 7.2); gradual smooth boundary
C2--74 to 102 cm; very gravelly loamy coarse sand, very dark grayish brown (10YR 3/2) dry, very dark brown (10YR 2/2) moist; single grain; loose, nonsticky and nonplastic; common very coarse, medium, and fine and many very fine roots; interstitial pores; prominent masses of oxidized iron around rock fragments, yellowish red (5YR 4/6) moist; 10 percent rounded basalt cobbles and 70 percent rounded basalt gravel, 5 percent of each coated with masses of oxidized iron; negative reaction to alpha-alpha dipyridyl; noneffervescent; neutral (pH 7.2); gradual smooth boundary
C3--102 to 150 cm; extremely gravelly loamy coarse sand, very dark grayish brown (10YR 3/2) dry, very dark brown (10YR 2/2) moist; single grain; loose, nonsticky and nonplastic; common medium and fine and many very fine roots; interstitial pores; prominent masses of oxidized iron around rock fragments, strong brown (7.5YR 5/8) moist; 3 percent rounded basalt cobbles and 65 percent rounded basalt gravel, 20 percent of each coated with masses of oxidized iron; positive reaction to alpha-alpha dipyridyl; noneffervescent; neutral (pH 7.2)
TYPE LOCATION: Umatilla County, Oregon, along Buckaroo Creek, about 24 km east of Pendleton; Thorn Hollow, Oregon, U.S. Geological Survey 7.5-minute topographic quadrangle; latitude 45.6628820, longitude -118.4835240, datum WGS 84 (coordinates derived from GPS location)
RANGE IN CHARACTERISTICS:
Thickness of mollic epipedon--26 to 34 cm
Depth to redoximorphic features (may be relict in upper part) and positive reaction to alpha-alpha dipyridyl--33 to 80 cm
Mean annual soil temperature--8 to 11 degrees C
Moisture control section--deeper than 30 to 90 cm; saturated with water within 100 cm of mineral soil surface 20 consecutive days or more at any time in November through May, but dry 45 to 70 days in July through September
Particle-size control section
*Content of clay--1 to 10 percent
*Content of rock fragments--35 to 75 percent
O horizon
*Thickness--0 to 3 cm
A horizon
*Value--2 to 4 dry, 2 or 3 moist
*Chroma--1 or 2 moist or dry
*Texture--gravelly loam, very cobbly loam
*Content of rock fragments--15 to 55 percent
*Content of gravel--10 to 35 percent
*Content of cobbles--0 to 30 percent
*Structure--granular, subangular blocky
*Reaction--6.6 to 7.3
*Combined thickness--26 to 33 cm
C horizon
*Hue--10YR, 2.5Y
*Chroma--0 to 2 moist or dry
*Content of rock fragments--15 to 55 percent
*Content of gravel--35 to 65 percent
*Content of cobbles--2 to 20 percent
*Content of stones--0 to 3 percent
*Structure--single grain, massive
*Reaction--6.6 to 7.3
COMPETING SERIES: None
GEOGRAPHIC SETTING:
Elevation--490 to 1200 m
Climate--temperate; hot, dry summers; cool, moist winters
Mean annual precipitation--300 to 840 mm
Mean January air temperature--about -1 degree C
Mean July air temperature--20 to 22 degrees C
Mean annual air temperature--7 to 10 degrees C
Frost-free season--60 to 120 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Bridgewater--mollic epipedon 50 to 100 cm thick; loamy-skeletal in particle-size control section; on stream terraces under black cottonwood and hawthorn
Joseph--no mollic epipedon; on gravel bars and flood plains at lower elevations under annual forbs
Patit Creek--mollic epipedon 50 to 100 cm thick; coarse-loamy in particle-size control section; on stream terraces under black cottonwood and hawthorn
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--somewhat poorly drained, moderately well drained
Saturated hydraulic conductivity (Ksat)--high in mollic epipedon, very high below
Flooding--rare or occasional, brief periods in December through May
Depth to seasonal water table--61 to 163 cm in December through April, 91 to 163 cm in November and May, below 112 cm in June through October
Oxygenated water seasonally passes through the soil profile in a lotic riparian system and does not produce visually observable anaerobic conditions.
USE AND VEGETATION:
Use--wildlife habitat, recreation, livestock grazing
Native vegetation--alder, black cottonwood, paper birch, snowberry, Woods' rose, arroyo willow, mallow ninebark, stinging nettle, field horsetail
DISTRIBUTION AND EXTENT: Northeastern Oregon; MLRAs 9 and 10; small extent
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Umatilla Indian Reservation, Umatilla County, Oregon; 2016; name means alder in native Umatilla language
REMARKS:
Diagnostic horizons and other features in this pedon
*Mollic epipedon--zone from 0 to 33 cm
*Redoximorphic concentrations--zone from 33 to 150 cm
*Positive reaction to alpha-alpha dipyridyl--below a depth of 102 cm
*Organic carbon--irregular decrease with increasing depth
*Particle-size control section--zone from 26 to 101 cm
*Lithochromic colors associated with basalt parent material
04/2016--Because stream channels are incised, the soils are thought to be drier than natural conditions and redoximorphic features at a higher depth in the profile are assumed to be relict in some pedons. Drainage classes are assigned based on local knowledge of soil-vegetation correlation; no field hydrologic studies were conducted.
6/2016--This official series description was updated according to SSR1 Technical Note 11--Content and Format of Official Series Descriptions (revised 12/2015).
National Cooperative Soil Survey
U.S.A.