LOCATION BLACKWOOD NEEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Pachic Haplustolls
TYPICAL PEDON: Blackwood loam with a 1 percent slope in cropland. (Colors are for dry soil unless otherwise noted.)
Ap--0 to 6 inches; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, very friable; neutral, abrupt smooth boundary.
A--6 to 14 inches; dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; weak medium and fine granular structure; soft, very friable; neutral; clear smooth boundary. (Combined thickness of A horizons range from 8 to 20 inches thick.)
Bw--14 to 23 inches; brown (10YR 4/3) loam, dark brown (10YR 3/3) moist; weak coarse prismatic structure parting to weak medium subangular blocky; slightly hard, friable; moderately alkaline; abrupt smooth boundary. (5 to 16 inches thick)
Bwb--23 to 28 inches; dark gray (10YR 4/1) loam; very dark gray (10YR 3/1) moist; weak coarse prismatic structure parting to moderate medium subangular blocky; slightly hard, friable; moderately alkaline; clear smooth boundary. (0 to 18 inches thick)
Bkb--28 to 34 inches; dark grayish brown (10YR 4/2) loam; very dark grayish brown (10YR 3/2) moist; weak coarse prismatic structure parting to moderate medium subangular blocky; slightly hard, friable; secondary carbonates on faces of peds and in root channels; strongly effervescent; moderately alkaline; clear smooth boundary. (0 to 18 inches thick)
BCkb--34 to 43 inches; pale brown (10YR 6/3) loam; brown (10YR 5/3) moist; weak medium and coarse subangular blocky structure; slightly hard, friable; threads and seams of secondary carbonates; violently effervescent; moderately alkaline; gradual smooth boundary. (6 to 18 inches thick)
C--43 to 80 inches; very pale brown (10YR 7/3) loam; pale brown (10YR 6/3) moist; massive; soft, very friable; violently effervescent; moderately alkaline.
TYPE LOCATION: Dundy County, Nebraska; about 18 miles north and 2 miles east of Benkelman, Nebraska; 2500 feet south and 100 feet east of the northwest corner of section 15, T. 4 N., R. 37 W. USGS Wauneta S.W. topographic quadrangle, latitude 40 degrees, 17 minutes, 30 seconds North and longitude 101 degrees, 29 minutes, 34 seconds West.
RANGE IN CHARACTERISTICS:
Control section clay content: averages 20 to 27 percent
Depth to carbonates: 20 to 36 inches
Mollic epipedon thickness: 20 to 48 inches
Solum thickness: 36 to 60 inches
Ap and A horizons:
Hue: 10YR
Value: 4 to 5 dry, 3 moist
Chroma: 1 to 3
Reaction: moderately acid to neutral
Texture: loam, very fine sandy loam, silt loam
Bw horizon:
Hue: 10YR
Value: 4 to 5 dry, 3 moist
Chroma: 2 to 3
Reaction: slightly to moderately alkaline
Texture: loam, very fine sandy loam
Bwb horizon (if it occurs):
Hue: 10YR
Value: 4 to 5 dry, 3 to 4 moist
Chroma: 1 to 3
Reaction: slightly to moderately alkaline
Texture: loam, clay loam
Comments: Some pedons have a calcareous Bwb horizon.
Bkb horizon (if it occurs):
Hue: 10YR
Value: 4 to 5 dry, 3 to 4 moist
Chroma: 1 to 3
Reaction: slightly to moderately alkaline
Texture: loam, clay loam
BCkb horizon:
Hue: 10YR
Value: 5 to 6 dry, 4 to 5 moist
Chroma: 2 to 3
Reaction: moderately to strongly alkaline
Texture: loam, clay loam
C horizon:
Hue: 10YR
Value: 5 to 7 dry, 4 to 6 moist
Chroma: 2 to 3
Reaction: moderately to strongly alkaline
Texture: loam, very fine sandy loam
COMPETING SERIES:
Duroc soils: do not have the polygenetic profile involving soil horizons of different soil-forming periods
Eltree soils: have carbonates at less than 20 inches, do not have the polygenetic profile involving soil horizons of different soil-forming periods, are moist throughout the series control section for longer periods
Graceville soils: have more clay, have gravelly sand between 40 and 60 inches, do not have the polygenetic profile involving soil horizons of different soil-forming periods, are moist throughout the series control section for longer periods
Trent soils: have more clay, do not have the polygenetic profile involving soil horizons of different soil-forming periods, are moist throughout the series control section for longer periods
Viborg soils: have glacial till material between 25 and 40 inches, do not have the polygenetic profile involving soil horizons of different soil-forming periods, are moist throughout the series control section for longer periods
Yankton soils: have carbonates at less than 20 inches, have glacial till material between 25 and 40 inches, do not have the polygenetic profile involving soil horizons of different soil-forming periods, are moist throughout the series control section for longer periods
GEOGRAPHIC SETTING:
Landscape: tablelands, uplands
Landform: plains
Slopes: 0 to 3 percent
Elevation: 3000 to 4000 feet
Parent material: loess of two geological ages separated in most places by a paleosol
Mean annual air temperature: 50 to 53 degrees F.
Mean annual precipitation: 14 to 18 inches
Frost-free period: 140 to 160 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Duroc soils: in swales
Lodgepole soils: in depressions that pond water for short duration
Ulysses soils: have a mollic epipedon less than 20 inches thick on higher landscapes
DRAINAGE AND PERMEABILITY: Well drained. Runoff is very low to low. Permeability is moderate.
USE AND VEGETATION: This soil is used for dry farmed and irrigated cropland. Corn, alfalfa, wheat and dry edible beans are the main crops.
DISTRIBUTION AND EXTENT: Southwestern Nebraska and possibly northeastern Colorado and northwestern Kansas.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Dundy County, Nebraska, 1995.
REMARKS: Blackwood soils were previously mapped with the Kuma soils. Laboratory data confirms that these soils lack the argillic horizon described as typical in the Kuma soils. In some places Blackwood soils lack a discernable paleosol but the combined thickness of the surface and subsurface horizons form a mollic epipedon more than 20 inches thick.
Diagnostic horizons and other features recognized in this pedon: mollic epipedon - the zone from the surface to a depth of 34 inches (Ap, A, Bw, Bwb and Bkb horizons); cambic horizon - the zone from 14 to 28 inches (Bw and Bwb horizons).
Additional Data: Pedon S89NE-057-007 sampled for National Soil Survey Laboratory.
ADDITIONAL DATA:
T: 5
K: .28
WEG: 5
WEI: 56