LOCATION REARDAN WA
Established Series
Rev. NCD/RJE/TLA/SHB
12/2011
REARDAN SERIES
The Reardan series consists of deep, well drained soils formed in loess of two ages and material weathered and basalt. These soils are on summits, backslopes and footslopes on loess hills. The average annual precipitation is about 17 inches and the mean annual air temperature is about 47 degrees F.
TAXONOMIC CLASS: Fine, mixed, superactive, mesic Typic Palexerolls
TYPICAL PEDON: Reardan silt loam, cultivated; on a neutral aspect with a slope of 1 percent at an elevation of 2,470 feet. When described on September 28, 2006, the soil was dry to 37 inches and moist below. (Colors are for moist soils unless otherwise noted.)
Ap--0 to 10 inches; dark grayish brown (10YR 4/2) silt loam, very dark brown (10YR 2/2) moist; moderate coarse subangular blocky structure; moderately hard, friable, nonsticky and slightly plastic; many very fine roots throughout; common very fine irregular pores; moderately acid (pH 5.6); clear wavy boundary. (7 to 10 inches thick)
Bw--10 to 15 inches; brown (10YR 4/3) silt loam, dark brown (10YR 3/3) moist; moderate coarse subangular blocky structure; moderately hard, friable, nonsticky and slightly plastic; many very fine roots throughout; many very fine and common fine irregular pores; slightly acid (pH 6.3); clear wavy boundary. (0 to 5 inches thick)
E--15 to 18 inches; pale brown (10YR 6/3) silt loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine roots throughout; many very fine and common fine irregular pores; neutral (pH 6.9); abrupt smooth boundary. (0 to 3 inches thick)
Btb--18 to 31 inches; dark yellowish brown (10YR 4/4) silty clay, dark yellowish brown (10YR 3/4) moist; strong medium prismatic structure parting to moderate medium subangular blocky; very hard, very firm, very sticky and very plastic; many very fine roots between peds; common very fine irregular pores; 40 percent clay films on all faces of peds and 40 percent pressure faces on all faces of peds; 2 percent fine black (10YR 2/1) iron-manganese nodules with sharp boundaries in matrix; neutral( pH 7.1); clear wavy boundary. (10 to 15 inches thick)
Btkb--31 to 37 inches; dark yellowish brown (10YR 4/4) silty clay loam, dark yellowish brown (10YR 3/6) moist; weak coarse prismatic structure parting to strong medium subangular blocky; hard, firm, very sticky and very plastic; common very fine roots between peds; common very fine and fine irregular pores; 20 percent clay films on all faces of peds and 60 percent pressure faces on all faces of peds; 2 percent fine black (10YR 2/1) iron-manganese nodules with sharp boundaries in matrix; 5 percent medium white (10YR 8/1) carbonate masses in matrix; neutral (pH 7.2), clear wavy boundary. (6 to 10 inches thick)
Bkqb--37 to 60 inches; dark yellowish brown (10YR 4/6) silt loam, dark yellowish brown (10YR 3/6) moist; weak coarse prismatic structure parting to strong medium subangular blocky; moderately hard, friable, extremely weakly cemented by silica, moderately sticky and moderately plastic; common very fine and fine irregular pores; 70 percent pressure faces on all faces of peds; 2 percent fine black (10YR 2/1), iron-manganese nodules with sharp boundaries in matrix; 10 percent extremely coarse white (10YR 8/1) carbonate masses on vertical faces of prisms; 70 percent medium extremely weakly cemented durinodes throughout; slightly alkaline (pH 7.5).
TYPE LOCATION: Spokane County, Washington; about 5 miles southwest of Medical Lake, WA; about 2,000 feet north and 440 feet west of the southeast corner of section 29, T. 24 N., R. 40 E. (Latitude 47 degrees, 32 minutes, 30.90 seconds N. and Longitude 117 degrees, 46 minutes, 52.20 seconds W.), NAD83. Waulkon, WA., topographic quadrangle..
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 47 to 52 degrees F
Moisture control section - dry for 60 to 90 days after the summer solstice, July to September, moist through October through June
Thickness of mollic epipedon - 10 to 20 inches
Depth to base of the argillic - 30 to 50 inches
Depth to secondary carbonates - 20 to 40 inches
Depth to durinodes - 31 to 60 inches (Greater than 50 % of durinodes slake in 1N HCl after prolonged soaking)
Clay content - 35 to 45 percent in the particle size control section
Ap and A horizons
Hue - 10YR or 7.5YR
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry, 1 to 3 moist
Texture - silt loam, loam or silty clay loam
Reaction - moderately acid to neutral
Bw horizon
Value - 4 or 5 dry, 3 or 4 moist
Chroma - 2 to 3 dry or moist
Reaction - slightly acid or neutral
E horizon (BE horizons in some pedons)
Value - 4 to 6 dry, 3 or 4 moist
Chroma - 3 or 4 dry or moist
Reaction - slightly acid or neutral
Btb horizon
Hue - 7.5YR, 10YR or 5YR
Value - 4 to 6 dry, 3 to 6 moist
Chroma - 3 to 6 dry, 3 or 4 moist
Texture - silty clay loam, silty clay, or clay
Reaction - neutral or slightly alkaline
Btkb horizon
Hue - 7.5YR or 10YR
Value - 4 to 6 dry, 3 to 6 moist
Chroma - 3 to 6 dry, 3 or 4 moist
Texture - silty clay loam, silty clay, or clay
Carbonate masses - 2 to 25 percent
Durinodes - 0 to 75 percent, fine to medium, extremely weakly to moderately cemented
Reaction - neutral to moderately alkaline
Bkqb horizon
Hue - 7.5YR or 10YR
Value - 4 to 6 dry, 3 to 6 moist
Chroma - 3 to 6 dry, 3 or 4 moist
Texture - silt loam or silty clay loam
Gravel content - 0 to 10 percent
Carbonate masses - 2 to 25 percent
Durinodes - 30 to 90 percent, fine to medium, extremely weakly to moderately cemented
Reaction - neutral to moderately alkaline
A weakly developed durpian is present in some pedons below 43 inches.
COMPETING SERIES: This is the
Achimin series. The Achimin soil has 2Bt and 2Bk horizons, has less than 40 percent clay in the Bt and 2Bt horizons of the typical pedon and does not have silica accumulation in the subsoil.
GEOGRAPHIC SETTING: Reardan soils are on summits, backslopes and footslopes of loess hills at elevations of 1,500 to 2,800 feet. Slope ranges from 0 to 25 percent. Thesesoils formed in loess of two ages and in some areas have weathered residuum from basalt.. These soils occur in a climate with warm, dry summers and cool, moist winters. The average January temperature is 25 degrees F.; the average July temperature is 66 degrees F.; and the mean annual temperature is 46 to 50 degrees F. The annual precipitation is 15 to 18 inches. The average frost free period is 100 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Athena,
Broadax and
Lance soils. Athena soils have a mollic epipedon greater than 20 inches thick and do not have an argillic horizon. Broadax soils have less than 35 percent clay in the particle size control section. Lance soils have an ochric epipedon and do not have an argillic horizon.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; slow to rapid runoff; moderately low saturated hydraulic conductivity.
USE AND VEGETATION: Mostly used for cropland and some is used for grazing. Small grains and alfalfa, clover and grass hay are common crops. Native vegetation is Idaho fescue, bluebunch wheatgrass, and balsamroot.
DISTRIBUTION AND EXTENT: Eastern Washington. Series is of moderate extent. MLRA's 8 and 9.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon.
SERIES ESTABLISHED: Spokane County, Washington, 1964.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from 0 to 15 inches (Ap and Bw horizons)
Argillic horizon - the zone from 18 to 37 inches (Btb and Btkb horizons)
Secondary carbonates - the zone from 31 to 60 inches (Btkb and Bkqb horizons)
Durinodes - the zone from 37 to 60 inches (Bkqb horizon)
Particle Size Control Section - the zone from 18 to 37 inches (Btb and Btkb horizon)
In 2006, the original type location was visited and found not to have a mollic eippedon and had duripan features. In light of these findings, the type location was moved to the current location to better represent the Reardan concept mapped during the Spokane County update.
In 2010, the Reardan series was reclassified from a Fine, mixed, superactive, Calcic Argixeroll to a Fine, mixed, superactive, mesic Typic Palexeroll due to a clay increase of 20 percent (absolute) within a vertical distance of less than 3 inches.
MLRA update investigation needed: the Reardan series mapped in Lincoln County needs to be investigated to confirm an abrupt textural change (Palexeroll criteria), the presence of durinodes and extent and influence of volcanic ash in surface layers and glaciofluvial parent materials.
National Cooperative Soil Survey
U.S.A.