LOCATION MILLBORO SD
Established Series
Rev. RFS-KJH, NJ
05/2013
MILLBORO SERIES
The Millboro series consists of very deep, well drained soils formed from clayey sediments weathered from marine shale of the Pierre Shale Formation. Millboro soils are on undulating upland plains in the Northern and Southern Rolling Pierre Shale Plains, MLRA's 63A and 63B. Slopes range from 0 to 15 percent. Mean annual precipitation is about 460 millimeters (18 inches), and mean annual air temperature is about 9 degrees C (48 degrees F).
TAXONOMIC CLASS: Fine, smectitic, mesic Typic Haplusterts
TYPICAL PEDON: Millboro silty clay - on plane, north-facing slope of 3 percent in a cultivated field. When described the soil was moist throughout. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 13 centimeters (0 to 5 inches); dark grayish brown (10YR 4/2) silty clay, very dark brown (10YR 2/2) moist; weak coarse and medium subangular blocky structure; hard, firm, sticky and plastic; neutral; abrupt smooth boundary.
A--13 to 18 centimeters (5 to 7 inches); dark grayish brown (10YR 4/2) silty clay, very dark grayish brown (10YR 3/2) moist; weak coarse and medium subangular blocky structure; very hard, firm, sticky and plastic; slightly alkaline; clear smooth boundary. [Combined A horizons are 10 to 25 centimeters (4 to 10 inches) thick.]
Bt1--18 to 33 centimeters (7 to 13 inches); dark grayish brown (10YR 4/2) clay, very dark grayish brown (10YR 3/2) moist; moderate medium and coarse prismatic structure parting to moderate fine and very fine subangular blocky; very hard, firm, sticky and plastic; neutral; clear smooth boundary.
Bt2--33 to 48 centimeters (13 to 19 inches); grayish brown (2.5Y 5/2) clay, dark grayish brown (2.5Y 4/2) moist; moderate medium prismatic structure parting to moderate fine and very fine subangular blocky; very hard, firm, sticky and plastic; many tongues 1 to 3 centimeters (1/4 to 1 inch) wide of dark grayish brown (10YR 4/2); strong effervescence; slightly alkaline; clear smooth boundary. [Combined Bt horizons are 20 to 61 centimeters (8 to 24 inches)thick.]
Bkss1--48 to 71 centimeters (19 to 28 inches); grayish brown (2.5Y 5/2) silty clay, dark grayish brown (2.5Y 4/2) moist; weak coarse prismatic structure parting to moderate medium blocky; extremely hard, very firm, very sticky and very plastic; many tongues 1 to 3 centimeters (1/4 to 1 inch) wide of dark grayish brown (10YR 4/2); many pressure faces and common slickensides; common medium accumulations of carbonate; strong effervescence; moderately alkaline; clear smooth boundary.
Bkss2--71 to 91 centimeters (28 to 36 inches); grayish brown (2.5Y 5/2) silty clay, dark grayish brown (2.5Y 4/2) moist; moderate medium and coarse blocky structure; extremely hard, very firm, very sticky and very plastic; many tongues 1 to 3 centimeters (1/4 to 1 inch) wide of dark grayish brown (10YR 4/2); many pressure faces and common slickensides; many fine and medium accumulations of carbonate; strong effervescence; moderately alkaline; clear wavy boundary. [Combined Bkss horizons are 0 to 51 centimeters (0 to 20 inches) thick.]
C--91 to 109 centimeters (36 to 43 inches); grayish brown (2.5Y 5/2) silty clay, dark grayish brown (2.5Y 4/2) moist; massive; very hard, very firm, very sticky and very plastic; few 1/4 inch tongues of dark grayish brown (10YR 4/2); few fine accumulations of carbonate; strong effervescence; moderately alkaline; gradual wavy boundary.
Ckz--109 to 142 centimeters (43 to 56 inches); light yellowish brown (2.5Y 6/4) silty clay, olive brown (2.5Y 4/4) moist; massive; hard, firm, sticky and plastic; few 1 centimeter (1/4 inch)wide tongues of dark grayish brown (10YR 4/2); many fine accumulations of carbonate and salts; strong effervescence; moderately alkaline; gradual wavy boundary.
C'--142 to 152 centimeters (56 to 60 inches); light yellowish brown (2.5Y 6/4) silty clay, olive brown (2.5Y 4/4) moist; massive; hard, firm, sticky and plastic; strong effervescence; moderately alkaline.
TYPE LOCATION: Tripp County, South Dakota; about 3 miles east of Witten; 2555 feet west and 240 feet north of southeast corner, sec. 25, T. 100 N., R. 78 W.
RANGE IN CHARACTERISTICS:
Soil Moisture Control Section:
The soil moisture control section is moist in some parts from April to July; intermittently moist from October to March; driest in August and September; typic ustic moisture regime.
Mean Annual Soil Temperature: 8 to 11 degrees C (46 to 52 degrees F)
Particle Size Control Section (weighted average):
Clay content: 45 to 60 percent
Sand content: 3 to 15 percent
The depth to free carbonate ranges from 18 to 51 centimeters (7 to 20 inches) in native grass, but some cultivated areas contain carbonate to the surface.
The depth to slickensides ranges from 41 to 61 centimeters (16 to 24 inches).
The thickness of mollic epipedon ranges from 18 to 48 centimeters (7 to 19 inches).
Common or many tongues of A horizon extend through the solum and into the C horizon of most pedons.
A Horizon:
Hue: 10YR or 2.5Y
Value: 3 to 5 dry and 2 to 3 moist
Chroma: 2 to 3
Texture: silty clay, silty clay loam, clay
Clay content: 30 to 45 percent
Reaction: neutral or slightly alkaline
Some pedons have a thin mantle of silt loam on the surface.
Bt Horizon:
Hue: 10YR or 2.5 Y
Value: 4 to 5 dry or 3 to 4 moist
Chroma: 3 to 4
Texture: clay or silty clay
Clay content: 45 to 60 percent
Reaction: neutral to moderately alkaline
Bkss horizon:
Hue: 2.5Y or 5Y
Value: 5 to 6 dry and 4 to 5 moist
Chroma: 2 to 4
Texture: clay or silty clay
Clay content: 45 to 60 percent
Reaction: slightly alkaline to moderately alkaline
Ped surface features: pressure faces and slickensides
Concentrations: secondary carbonates are present
Note: Some pedons may have a BC horizon.
C Horizon:
Hue: 2.5Y or 5Y
Value: 5 to 7 dry and 4 to 5 moist
Chroma: 2 to 4
Texture: clay or silty clay
Fragments: few to many fragments of shale
Clay content: 45 to 60 percent
Reaction: slightly alkaline or moderately alkaline
Ped/Secondary feature: accumulations of salt in the lower part of some pedons
COMPETING SERIES:
Currently
Goessel is the only competing series. Goessel has a warmer mean annual soil temperature and a wetter soil moisture regime.
GEOGRAPHIC SETTING:
Parent Material: clayey sediments weathered from Pierre Shale
Landscape: nearly level to rolling uplands
Landform: gently sloping to undulating plains
Slope: 0 to 15 percent
Slope shape: plane to convex
Mean annual air temperature: 6 to 10 degrees C (43 to 50 degrees F)
Mean annual precipitation: 400 to 700 millimeters (16 to 28 inches)
GEOGRAPHICALLY ASSOCIATED SOILS:
These are the
Boro,
Lakoma,
Reliance,
Witten and McClure soils. Boro and Lakoma soils have convex slopes and are above the Millboro soils. Boro soils do not have a mollic epipedon. Lakoma soils have shale between depths of 50 and 100 centimeters (about 20 to 40 inches). Reliance and McClure have plane slopes on tablelands above the Millboro soils and contain less clay. Witten soils are in swales.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage: well drained
Saturated Hydraulic Conductivity: moderately low
Runoff: medium to very high depending on slope
USE AND VEGETATION:
Mostly cropped to winter wheat, corn grain sorghum and alfalfa. Native vegetation mainly is western wheatgrass, green needlegrass, blue grama, and sideoats grama.
DISTRIBUTION AND EXTENT:
South-central South Dakota. It is mapped extensively in MLRA's 63A and 63B and also in MLRA 66.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED:
Hughes County, South Dakota, 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 33 centimeters (13 inches, this includes the Ap, A and Bt1 horizons); argillic horizon - the zone from 18 to 48 centimeters (7 to 19 inches, this includes the Bt1 and Bt2 horizons); slickensides - the zone form 48 to 91 centimeters (19 to 36 inches, this includes the Bkss1 and Bkss2 horizons).
NCJ 5/2013 - Overall update of Range in Characteristics, competing series, diagnostic features and change to tabular format.
ADDITIONAL DATA:
KSSL Pedon number 40A2510; user pedon ID 71SD123003.
National Cooperative Soil Survey
U.S.A.