LOCATION BRISTOW NE
Established Series
Rev. OI-JIB-MD
11/2022
BRISTOW SERIES
The Bristow series consists of shallow, well drained slowly permeable soils formed in light colored shales. The upland soils have slopes ranging from 6 to 60 percent. Mean annual temperature is about 49 degrees F, and the mean annual precipitation is about 22 inches.
TAXONOMIC CLASS: Clayey, gypsic, mesic, shallow Typic Ustorthents
TYPICAL PEDON: Bristow silty clay - on a 25 percent convex west-facing slope in rangeland. When described the soil was dry throughout. (Colors are for dry soil unless otherwise stated.)
A--0 to 7 inches; pale brown (10YR 6/3) silty clay, dark yellowish brown (10YR 4/4) moist; moderate medium subangular blocky structure parting to moderate fine and very fine granular; hard, friable; many very fine and fine roots; strong effervescence; mildly alkaline; clear wavy boundary. (5 to 10 inches thick)
C--7 to 17 inches; light yellowish brown (2.5Y 6/4) shaly clay, light olive brown (2.5Y 5/4) moist; massive; more than 75 percent partially weathered shale fragments that break down upon wetting; contains visible calcium carbonate and gypsum in the seams and fractures; contain very fine and fine roots; violent effervescence; moderately alkaline; gradual wavy boundary. (0 to 10 inches thick)
Cr--17 to 60 inches; very pale yellow (10YR 7/3) and yellow (2.5Y 7/6) bedded shale, pale brown (10YR 5/6) moist; massive breaking to strong medium to very coarse platy shale fragments; shale fragments break down upon wetting; few fine roots greater than 4 inches apart in seams and cracks in upper part and few fine flat roots greater than 4 inches apart in seams and cracks in lower part; contains visible calcium carbonates and gypsum in the seams and fractures; mildly alkaline.
TYPE LOCATION: Boyd County, Nebraska; about 1 mile south of Bristow, Nebraska; 600 feet south and 150 feet west of the northeast corner of sec. 22, T. 33 N., R. 11 W.
RANGE IN CHARACTERISTICS: Depth to shale typically is 8 to 16 inches and ranges from 5 to 20 inches. Thickness of the solum is 5 to 10 inches. Reaction in the solum is mildly or moderately alkaline and the calcium carbonate equivalent ranges from 15 to 25 percent. The carbonate free clay ranges from 38 to 55 percent in the control section. The soil colors are largely inherited from the parent shale.
The A horizon has hue of 10YR or 2.5Y, value of 4 through 6 and 3 through 5 moist, and chroma of 3 or 4. Dominant texture is silty clay and less frequently heavy silty clay loam, clay loam, or clay.
The C horizon has hue of 10YR or 2.5Y, value of 6 through 8 and 4 through 6 moist, and chroma of 4 through 6.
The Cr horizon has hue of 10YR or 2.5Y, value of 6 through 8 and 4 through 7 moist, and chroma of 4 through 6. It contains from 30 to 40 percent calcium carbonates and gypsum in seams and fractures.
COMPETING SERIES: Bristow is the only series in this family. Similar soils are
Monowi,
Okaton, and
Sansarc. Monowi soils are 20 to 40 inches deep to light colored shale. Okaton and Sansarc soils have montmorillonitic mineralogy and lack the high amount of gypsum in the parent shale. Also, Sansarc soils are formed in dark shale.
GEOGRAPHIC SETTING: The Bristow soils have steep slopes in areas called breaks or dissected shale plains. Slope gradients range from 6 to over 60 percent. They are formed in clay residuum weathered from light colored, calcareous, gypsiferous, soft shales. The mean annual precipitation ranges from 20 to 24 inches, and the mean annual air temperature ranges from 47 to 52 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Boyd,
Lakoma,
Monowi,
Promise,
Reliance, and
Sansarc. The Boyd, Lakoma, Monowi, and Promise soils occupy more gentle slopes below Bristow and are deeper to shale. Reliance soils are deeper, developed in loess and have mollic epipedons and argillic horizons, and are on nearly level to gently sloping areas. Sansarc soils have montmorillonitic mineralogy and lack the high amount of gypsum. They occur generally above Bristow.
DRAINAGE AND PERMEABILITY: Well drained; surface runoff is very rapid. Permeability is slow.
USE AND VEGETATION: These soils are primarily in native range; the important grasses are big bluestem, little bluestem, sideoats grama, indiangrass, and needleandthread.
DISTRIBUTION AND EXTENT: North-central Nebraska and possibly south-central South Dakota. These soils are of moderate extent.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Salina, Kansas.
SERIES ESTABLISHED: Boyd County, Nebraska, 1976.
REMARKS: Laboratory sample number 77PO214-77PO219.
National Cooperative Soil Survey
U.S.A.