LOCATION TEKOA WA+IDEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Vitrandic Argixerolls
TYPICAL PEDON: Tekoa gravelly ashy silt loam, rangeland - (colors are for dry soils unless otherwise stated).
A1--0 to 3 inches; dark grayish brown (10YR 4/2) gravelly ashy silt loam, very dark brown (10YR 2/2) moist; weak thin and medium platy structure parting to moderate fine and medium granular; slightly hard, friable, slightly sticky and slightly plastic; many roots; many very fine and fine pores; 30 percent channers; slightly acid (pH 6.1); clear wavy boundary. (3 to 9 inches thick)
A2--3 to 7 inches; grayish brown (10YR 5/2) gravelly ashy silt loam, very dark grayish brown (10YR 3/2) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many roots; many very fine and fine pores; 30 percent channers; slightly acid (pH 6.2); clear wavy boundary. (0 to 6 inches thick)
BA--7 to 14 inches; brown (10YR 5/3) very gravelly loam, dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many roots; many very fine and fine pores; 35 percent channers; slightly acid (pH 6.3); clear wavy boundary. (7 to 10 inches thick)
Bt--14 to 20 inches; pale brown (10YR 6/3) very gravelly heavy loam, brown (10YR 4/3) moist; moderate fine and medium prismatic structure; slightly hard, friable, moderately sticky and moderately plastic; common roots; many fine and medium pores; many faint clay films on peds and in pores; 35 percent channers; slightly acid (pH 6.4); clear wavy boundary. (6 to 15 inches thick)
BC--20 to 38 inches; yellow (10YR 7/6) extremely gravelly loam, yellowish brown (10YR 5/6) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few roots; 80 percent channers; slightly acid (pH 6.4); clear wavy boundary. (0 to 18 inches thick)
R--38 inches; fractured shale.
TYPE LOCATION: Whitman County, Washington; 1,700 feet west and 200 feet south of the northeast corner of sec. 2, T. 20 N., R. 45 E.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 47 to 50 degrees F.
Depth to a lithic contact - 20 to 40 inches.
Moisture control section - these soils are usually moist, but are dry for 60 to 75 consecutive days in the moisture control section following summer solstice.
Rock fragments - 35 to 60 percent rock fragments in the particle-size control section.
Clay content - 10 to 30 percent clay.
Thickness of the mollic epipedon - 7 to 20 inches thick.
Thickness of volcanic ash influence - 7 to 16 inches
Estimated properties of ash influence layer:
Volcanic glass content - 5 to 20 percent,
Acid-oxalate extractable Al + Fe - 0.4 to 1.0 percent
15-bar water retention - 5 to 10 percent (air dried) samples
A horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3, moist or dry
Reaction - neutral to moderately acid
BA horizon
Hue - 10YR or 7.5YR
Value - 5 or 6 dry, 3 or 4 moist
Chroma - 3 or 4, moist or dry
Texture- loam or silt loam
Rock fragment content - 20 to 60 percent channers
Reaction - neutral to moderately acid.
Bt horizon
Hue - 10YR or 7.5YR
Value - 5 or 6 dry, 3 or 4 moist
Chroma - 3 or 4, moist or dry
Texture - silt loam, loam, or clay loam
Rock fragment content - 35 to 60 percent channers.
Reaction - slightly acid or moderately acid
BC horizon
Hue - 10YR or 7.5YR
Value - 5 to 7 dry, 3 to 5 moist
Chroma - 3 or 4
Texture - loam or silt loam
Rock fragment content - 35 to 80 percent channers
Reaction - slightly acid or moderately acid.
COMPETING SERIES: These are the Akana, Blint, Brysill, Bunselmeier, Cubhill, Hehe, Hovelton, Lainand, Leidl, McDaniel, Millhouse, Nint, Norod, and Skooker soils.
Ackna (WA) - are very deep
Blint (WA) - are dry for 90 to 100 days following the summer solstice
Brysill (WA) - are very deep
Bunselmeier (CA) -have sandy clay loam textures and are 40 to 60 inches to unweathered cinders
Cubhill (WA) - are very deep
Hehe (OR) - have 10 to 25 percent medium, coarse and very coarse sand, and are dry for 60 to 90 days following the summer solstice
Hovelton (ID) - are dominated by cobble and stone size basalt and welded tuff rock fragments in the particle-size control section
Lainand (WA) - are 40 to 60 inches to a lithic contact
Leidl (WA) - are dry for 75 to 90 days following the summer solstice
McDaniel (WA) - are very deep
Millhouse (WA) - are very deep and are dry for 100 to 120 days following the summer solstice
Nint (WA) - are dry for 75 to 90 days following the summer solstice
Norod (WA) - are 25 to 38 inches to secondary carbonates and are dry for 100 to 120 days following the summer solstice
Skooker (OR) - are 40 to 60 inches to a lithic contact
GEOGRAPHIC SETTING: Tekoa soils are on mountain slopes at elevation of 2,000 to 4,000 feet. Higher elevations are only on south slopes. Slopes are 3 to 65 percent. These soils formed in loess and colluvium from sedimentary and medisedimentary rocks including shale, phyllite, argillite, sandstone, quartzite, and siltstone. The climate is characterized by warm, dry summers and cool, moist winters. Average annual precipitation is 20 to 30 inches including about 3 feet of snow. Average January temperature is 24 degrees F, average July temperature is 66 degrees F, and mean annual air temperature is 45 to 48 degrees F. The frost-free season is 100 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: This is the Schumacher series. Schumacher soils are fine-loamy and deeper than 40 inches.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability; slow to rapid runoff.
USE AND VEGETATION: Grazing, wildlife, small grains, alfalfa, and grass. Native vegetation is scattered ponderosa pine, Douglas-fir, pinegrass, Idaho fescue, bluebunch wheatgrass and shrubs.
DISTRIBUTION AND EXTENT: Northeastern Washington and northern Idaho. Series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Spokane County, Washington, 1964.
REMARKS: Diagnostic horizons and features recognized in this soil include:
Mollic epipedon - the zone from the surface to 14 inches (A1, A2, and BA horizons)
Argillic horizon - the zone from 14 to 20 inches (Bt horizon)
Lithic contact - at 38 inches
Particle-size control section - the zone from 14 to 20 inches (Bt horizon)
Vitrandic feature - the zone from 0 to 7 inches (A1 and A2 horizons)
Changes made to description 1/07 using MLRA approach:
Vegetation revised to reflect a concept of a mesic soil at the transition between MLRA 9 and MLRA 43A.
Classification updated from Loamy-skeletal, mixed, superactive, mesic Ultic Argixerolls to Loamy-skeletal, mixed, superactive, mesic Vitrandic Argixerolls.
Paralithic contact changed to lithic contact.
Horizonation updated.