LOCATION PAULSON WY+IDEstablished Series
TAXONOMIC CLASS: Fine, smectitic Pachic Argicryolls
TYPICAL PEDON: Paulson silt loam, grassland. (Colors are for dry soil unless otherwise noted.)
A--0 to 5 inches; dark reddish gray (5YR 4/2) silt loam, dark reddish brown (5YR 2/2) moist; strong fine crumb and granular structure; soft, very friable; neutral (pH 7.0); clear smooth boundary. (4 to 8 inches thick)
BA--5 to 10 inches; dark reddish gray (5YR 4/2) silty clay loam, dark reddish brown (5YR 2/2) moist; moderate fine subangular blocky structure that parts to strong fine granules; slightly hard, very friable; neutral (pH 7.0); clear smooth boundary. (4 to 6 inches thick)
Bt1--10 to 27 inches; dark reddish gray (5YR 4/2) silty clay, dark reddish brown (5YR 3/2) moist; strong fine prismatic structure that parts to strong fine angular blocks; extremely hard, very friable; faint continuous clay films in root channels and pores; neutral (pH 7.0); clear smooth boundary. (8 to 22 inches thick)
Bt2--27 to 34 inches; reddish brown (5YR 5/3) silty clay, dark reddish brown (5YR 3/3) moist; strong fine prismatic structure that parts to strong fine angular blocks; extremely hard, very friable; faint continuous clay films on the surface of peds, in root channels and pores; neutral (pH 7.0); clear wavy boundary. (0 to 10 inches thick)
Bt3--34 to 41 inches; reddish brown (5YR 5/3) silty clay loam, reddish brown (5YR 4/3) moist; moderate medium prismatic structure that parts to moderate fine angular blocks; very hard, very friable; faint clay films on faces of peds; some clay films in root channels; calcareous; moderately alkaline (pH 8.2); gradual wavy boundary. (6 to 8 inches thick)
Ck--41 to 60 inches; light reddish brown (2.5YR 6/3) silt loam, reddish brown (2.5YR 4/3) moist; massive; hard, friable; visible secondary calcium carbonate occurring as concretions and in thin seams and streaks; calcareous; moderately alkaline. (pH 8.2).
TYPE LOCATION: Lincoln County, Wyoming; NW1/4 SW1/4 of sec. 17, T.31N., R.119W.
RANGE IN CHARACTERISTICS: The mollic epipedon is 16 to 50 inches thick, depth to calcareous material is 15 to 40 inches, the solum in 20 to 50 inches thick, and there is no bedrock or strongly contrasting substratums above 40 inches or immediately below the solum if thicker than 40 inches. The mollic epipedon contains .8 to 3 percent organic carbon which decreases uniformly with depth. The soil is 80 to 100 percent base saturated. Cation exchange capacity is 60 to 80 millequivalent per 100 grams of clay. Content of coarse fragments is typically less than 5 percent and ranges from 0 to 15 percent. Mean annual soil temperature is 32 degrees to 46 degrees F. and mean summer soil temperature is 40 degrees to 58 degrees F.
The A horizon has hue of 7.5YR or 5YR, value of 4 or 5 dry and 2 or 3 moist and chroma of 1 through 3. It typically has granular or crumb structure but is subangular blocky in some pedons. It is soft to slightly hard and slightly acid to slightly alkaline.
The Bt horizon has hue of 5YR or 2.5YR, value of 4 through 6 dry and 3 or 4 moist and chroma of 2 or 3. It usually has prismatic structure but is angular blocky in some pedons. It is typically silty clay loam or light silty clay but ranges from 35 to 50 percent, silt from 20 to 55 percent, and sand from 5 to 40 percent. Oriented clay films occur in some part of this horizon. It is slightly acid to slightly alkaline.
The Ck horizon has hue of 5YR through 10R. It contains 4 to about 12 percent calcium carbonate equivalent. It is moderately to strongly alkaline.
COMPETING SERIES: These are the Bischoff, Burnette, Cochetopa, Faim, Fulcher, Grouseville, Guero, Leemorris, Mancos, Mayflower, Perinos, Richens, Runlett, Skutum, Teedown, and Winridge series. The Bischoff, Cochetopa, Faim, Grouseville, Guero, Perinos, and Teedown soils do not have horizons of secondary carbonate accumulation. The Burnette soils have hues of 10YR or yellower throughout. The Fulcher soils have hues of 7.5YR or yellower throughout. The Leemorris, Mancos, Mayflower, Runlett, and Winridge soils are moderately deep to a lithic contact and do not have horizons of secondary carbonate accumulation. The Richens soils are deep to a lithic contact and do not have horizon of secondary carbonate accumulation. The Skutum soils are deep to a paralithic contact and do not have horizons of secondary carbonate accumulation.
GEOGRAPHIC SETTING: The Paulson series occurs on gently to moderately sloping alluvial fans and valley filling sideslopes. Slopes range from 2 to about 20 percent. The soils formed in alluvial fan sediments derived principally from reddish brown sandstone and shale. In some localities the soil may have a strong loess influence in the upper horizon. At the type location the average annual precipitation is 18 inches with nearly equal amounts of precipitation occurring during most months. The mean annual temperature is 39 degrees F., the mean summer temperature is 58 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Buckskin and Lost Creek soils. Buckskin soils lack a mollic epipedon more than 16 inches thick, and lack consistent horizons of secondary carbonate accumulation. Lost Creek soils have B2t horizons with less than 35 percent clay.
DRAINAGE AND PERMEABILITY: Well-drained; medium runoff; moderately slow permeability.
USE AND VEGETATION: These soils are used for dry and irrigated cropland, and as native pastureland. Principal native vegetation is bluegrass.
DISTRIBUTION AND EXTENT: Mountainous areas of western Wyoming and Colorado. The series has a moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Star Valley Area, Idaho and Wyoming, 1971.