LOCATION SAVO SD+NEEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Aridic Argiustolls
TYPICAL PEDON: Savo silt loam - on a plane slope of 2 percent in native range. When described the soil was dry throughout. (Colors are for dry soil unless otherwise stated.)
A--0 to 5 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak medium and coarse subangular blocky structure parting to weak fine granular; slightly hard, very friable; common fine and very fine roots; slightly acid; clear wavy boundary. (3 to 9 inches thick)
Bt1--5 to 9 inches; dark grayish brown (10YR 4/2) silty clay loam, very dark grayish brown (10YR 3/2) moist; moderate medium prismatic structure parting to moderate fine subangular blocky; hard, friable; patchy clay films on faces of peds; common very fine roots; slightly acid; clear wavy boundary.
Bt2--9 to 16 inches; grayish brown (2.5Y 5/2) silty clay loam, dark grayish brown (2.5Y 4/2) moist; moderate coarse prismatic structure parting to moderate fine subangular blocky; very hard, firm; patchy clay films on surfaces of peds; few very fine roots; neutral; clear wavy boundary. (Combined Bt horizon is 9 to 18 inches thick.)
Bk1--16 to 21 inches; light yellowish brown (2.5Y 6/4) silty clay loam, light olive brown (2.5Y 5/4) moist; moderate coarse subangular blocky structure parting to moderate fine subangular blocky; very hard, firm; few very fine roots; common fine accumulations of carbonate; strong effervescence; slightly alkaline; gradual wavy boundary.
Bk2--21 to 42 inches; pale yellow (2.5Y 7/4) silty clay loam, light olive brown (2.5Y 5/4) moist; weak coarse subangular blocky; very hard, firm; common fine accumulations of carbonate; violent effervescence; slightly alkaline; diffuse wavy boundary. (Combined Bk horizon is 6 to 45 inches thick.)
C--42 to 60 inches; light yellowish brown (2.5Y 6/4) silty clay loam, light olive brown (2.5Y 5/4) moist; massive; very hard, firm; violent effervescence; slightly alkaline.
TYPE LOCATION: Fall River County, South Dakota, about 3 miles east of Oelrichs, 1,200 feet west and 300 feet south of the NE corner of sec. 16, T. 10 S., R. 8 E.
RANGE IN CHARACTERISTICS: The depth to carbonates ranges from 12 to 20 inches. Thickness of the mollic epipedon ranges from 7 to 15 inches and extends into the Bt horizon.
The A horizon has hue of 10YR, value of 4 or 5 and 2 or 3 moist, and chroma of 1 or 2. It is silt loam or silty clay loam. It is slightly acid or neutral.
The Bt1 horizon has hue of 10YR, value of 4 or 5 and 2 or 3 moist, and chroma of 1 or 2. The Bt2 horizon has hue of 10YR or 2.5Y, value of 4 or 5 and 3 or 4 moist, and chroma of 2 or 3. The Bt horizon is silty clay loam, clay loam, silty clay, or clay, typically averaging between 35 and 45 percent clay, but has a range of 35 to 50 percent clay. It has less than 15 percent fine and coarser sand and up to 25 percent very fine sand. Reaction is slightly acid or neutral in the Bt1 horizon and neutral or slightly alkaline in the Bt2 horizon.
The Bk horizon has hue of 2.5Y or 10YR, value of 5 to 7 and 4 to 6 moist, and chroma of 2 to 4. It is silt loam, silty clay loam, loam or clay loam. It has few or common fine or medium accumulations of carbonate. It is slightly or moderately alkaline.
The C horizon has hue of 2.5Y or 10YR, value of 5 to 7 and 5 or 6 moist, and chroma of 2 to 4. It is silt loam, silty clay loam, loam or clay loam. It is slightly or moderately alkaline. In some pedons, the soil is underlain by sand and gravel and soft shale between depths of 40 and 60 inches.
COMPETING SERIES: These are the Ashfork, Blackpipe, Boneek, Boquillas, Chapin, Collbran, Emigrant, Huggins, Kube, Leyden, Loma, Nuncho, Nunn, Querc, Rednun, Richfield, Ryus, Showlow, Sofia, Standley, Thunderbird, Torreon, and Wormser soils in the same family. Ashfork, Blackpipe, Boquillas, Chapin, Emigrant, Huggins, Leyden, Querc, and Wormser soils have bedrock between depths of 20 and 40 inches. In addition, Chapin and Boquillas soils have hue of 7.5YR or redder in the argillic horizon; Emigrant, Querc, and Wormser soils contain more sand coarser than very fine sand; and Huggins soils have higher CEC/clay ratios. Boneek, Collbran, Loma, and Rednun soils have hue of 7.5YR or redder. In addition, Loma soils have carbonates throughout and Rednun soils contain more fine sand coarser than very fine sand. Kube soils have higher CEC/clay ratios. Nuncho and Nunn soils contain more than 15 percent fine or coarser sand in the Bt horizon. Richfield soils have warmer temperatures. Ryus soils have carbonates at or near the surface. Showlow and Standley soils contain more coarse fragments. Sofia soils contain more than 50 percent clay. Thunderbird soils contain more fine or coarser sand and formed in material weathered from basalt. Torreon soils have thicker sola and formed in sediments influenced by basalt.
GEOGRAPHIC SETTING: The Savo soils are on nearly level to moderately sloping terraces and uplands with slope gradients ranging from 0 to 9 percent. Slopes are plane to slightly convex. The Savo soils formed in silty sediments of mixed mineral origin ranging from 40 inches to more than 10 feet thick. Mean annual temperature ranges from 39 to 48 degrees F, and mean annual precipitation ranges from 12 to 19 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Blackpipe and Nunn soils and the Altvan, Keith, and Kyle soils. The Altvan, Blackpipe, Keith, and Nunn soils are on similar landscapes. Altvan soils are fine-loamy over sandy or sandy-skeletal. Keith soils are fine-silty. Kyle soils do not have a mollic epipedon, have a very-fine control section and are on lower landscapes.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is slow on 0 to 2 percent slopes and medium on 2 to 9 percent slopes. Permeability is moderately slow.
USE AND VEGETATION: Savo soils are cultivated and in rangeland. The principal crops are corn, sorghum, small grain, and alfalfa. Western wheatgrass, blue grama, green needlegrass, sideoats grama, and needleandthread are the main native grasses.
DISTRIBUTION AND EXTENT: South-central and western South Dakota. The Savo series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Butte County, South Dakota, March 1970.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of about 9 inches (A and Bt1 horizons); argillic horizon - the zone from a depth of about 5 to 16 inches (Bt1 and Bt2 horizons).