LOCATION OBERT                   NE

Established Series
Rev. LGR, SAS, GHC
03/2020

OBERT SERIES

The Obert series consists of very deep, poorly drained and very poorly drained soils that formed in calcareous, loamy alluvium. These soils are on flood plains and have slopes of 0 to 2 percent. Mean annual temperature is about 10 degrees C. (50 degrees F.) and mean annual precipitation is about 640 millimeters (25 inches) at the type location.

TAXONOMIC CLASS: Fine-silty, mixed, superactive, calcareous, mesic Cumulic Endoaquolls

TYPICAL PEDON: Obert silt loam with a slope of less than 1 percent in native grass. (Colors are for dry soil unless otherwise stated.)

A1--0 to 25 centimeters (0 to 10 inches); gray (10YR 5/1) silt loam, very dark gray (10YR 3/1) moist; moderate fine granular structure; slightly hard, friable; violent effervescence; moderately alkaline; gradual smooth boundary.

A2--25 to 64 centimeters (10 to 25 inches); dark gray (10YR 4/1) silty clay loam, black (10YR 2/1) moist; weak fine granular structure; hard, firm; few fine distinct light yellowish brown (10YR 6/4) iron masses in the matrix; violent effervescence; moderately alkaline; gradual smooth boundary. (Combined A horizon is 38 to 102 centimeters (15 to 40 inches) thick)

ACg--64 to 102 centimeters (25 to 40 inches); dark gray (10YR 4/1) silty clay loam, very dark gray (10YR 3/1) moist; weak medium and coarse subangular blocky structure; hard, firm; few fine distinct brown (10YR 4/3) iron masses in the matrix; slightly alkaline; clear smooth boundary. (0 to 38 centimeters (0 to 15 inches) thick)

Cg--102 to 152 centimeters (40 to 60 inches); stratified dark gray (10YR 4/1) and light brownish gray (10YR 6/2) loam, very dark gray (10YR 3/1) and dark grayish brown (10YR 4/2) moist; massive; slightly hard, friable; slightly alkaline.

TYPE LOCATION: Knox County, Nebraska; 1.6 kilometers (1 mile) west and 1.6 kilometers (1 mile) north of Creighton; 457 meters (1500 feet) south and 91 meters (300 feet) east of the northwest corner, sec. 20, T. 29 N., R. 5 E.

RANGE IN CHARACTERISTICS:
Soil moisture: wet in the control section from November through June and moist from July through October
Mean annual soil temperature: 8 to 10 degrees C (46 to 50 degrees F)
Depth to secondary calcium carbonate: 0 to 25 centimeters (0 to 10 inches)
Calcium carbonate equivalent A horizon: commonly 5 to 10 percent and ranges 1 to 15 percent
Depth to redox concentrations: 10 to 41 centimeters (4 to 16 inches)
Depth to episaturation: + 15 to 46 centimeters (+6 to 18 inches) from November to June
Thickness mollic epipedon: more than 61 centimeters (24 inches)
Thickness of the solum: 61 to 122 centimeters (24 to 48 inches)

A horizon:
Hue: 10YR to 5Y or neutral
Value: 3 to 5, 2 or 3 moist
Chroma: 0 to 2
Texture: silt loam or silty clay loam
Clay content: 18 to 35 percent
Sand content: < 15 percent
Reaction: Slightly alkaline or moderately alkaline

ACg horizons: (if present)
Hue: 10YR to 5Y
Value: 3 to 5, 2 to 4 moist
Chroma: 1 or 2
Texture: Silt loam or silty clay loam
Mollic epipedon: at least 61 centimeters (24 inches) thick
Clay content: 18 to 35 percent
Sand content: < 15 percent
Reaction: Slightly alkaline or moderately alkaline

Cg horizons:
Hue: 10YR, 2.5Y or 5Y
Value: 4 to 7, 3 to 6 moist
Chroma: 1 or 2
Texture: Silt loam, or silty clay loam
Clay content: 18 to 35 percent
Sand content: < 15 percent
Reaction: Slightly alkaline or moderately alkaline

COMPETING SERIES: These are the Badus, Calco, Devilsgait, Lamo, Salmo, Sawabash and Wingdale series.
Badus soils formed in silty alluvium over glacial till on upland drainageways and depressions.
Calco soils are in an area of more rainfall of 690 to 860 millimeters (27 to 34 inches).
Devilsgait soils are dry in all parts of the soil moisture control section for more than 60 cumulative days in the 120 days following the summer solstice.
Lamo soils have a seasonal high-water table at a depth of 46 to 91 centimeters (18 to 36 inches) during the growing season.
Salmo soils have gypsum and other salts throughout the particle size control section.
Sawabash soils have a cambic horizon and receive more than 76 centimeters (30 inches) of annual precipitation.
Wingdale soils have a mean annual precipitation is 230 to 360 millimeters (9 to 14 inches).

GEOGRAPHIC SETTING:
Parent material: Calcareous, loamy, alluvium
Landform: Floodplains
Slopes: 0 to 2 percent
Mean annual temperature: 9 to 11 degrees C. (48 to 52 degrees F.)
Mean annual precipitation: 560 to 760 millimeters (22 to 30 inches)
Frost-free period: 140 to 160 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Coleridge, Gibbon, Kennebec, Leshara, Salmo, Silver Creek, Wabash and Zook soils.
Coleridge and Gibbon soils are higher on the landscape and are saturated lower in the series control section.
Gibbon and Silver Creek soils have a thinner mollic epipedon.
Silver Creek soils are higher on the landscape and are in the fine family.
Kennebec soils contain less clay in the control section, are higher on the landscape and are saturated lower in the profile.
Wabash soils contain more clay in the control section and lack free carbonates above a depth of 102 centimeters (40 inches).

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage: poorly drained and very poorly drained
Runoff: low
Saturated Hydraulic Conductivity: moderately high
Flooding: occasionally or frequently flooded
Water table depth: Poorly drained, 0 to 46 centimeters (0 to 18 inches); very poorly drained, + 15 to 30 centimeters (+6 to 12 inches)

USE AND VEGETATION: The Obert soils are used mainly for rangeland or hayland. Vegetation is primarily big bluestem, switchgrass, indiangrass, prairie cordgrass, reedgrasses, and sedges. See Remarks section for native vegetative cover in Nebraska.

DISTRIBUTION AND EXTENT: Nebraska and possibly South Dakota. The Obert series is of moderate extent.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Salina, Kansas.

SERIES ESTABLISHED: Knox County, Nebraska, 1989.

REMARKS:
Diagnostic horizons and features recognized in the pedon are:
Mollic epipedon: 0 to 102 centimeters (0 to 40 inches) (A1, A2 and AC horizons)
Aquic soil conditions: saturated from 40 and 50 centimeters (16 to 20 inches) for at least a few days when the soil temperature is above biological zero of 5 degrees C. (41 degrees F.)
Endosaturation: saturated in all layers from the upper boundary of saturation to a depth of 200 centimeters (79 inches) or more from the mineral soil surface
Upper boundary of saturation: less than 46 centimeters (18 inches) during late winter through early summer in most years and over the surface in some places

In prior surveys, the Obert soils were mapped and correlated as Lamo, wet. The Lamo series is being divided into the Lamo (somewhat poorly drained) and Obert (poorly drained and very poorly drained) series. They are in land Class IIw and Vw respectively. About 6,000 hectares (15,000 acres) of Lamo, wet, have been correlated in Nebraska. They will be mapped or recorrelated as Obert soils in the future.

Classification changed from Haplaquolls to Endoaquolls according to changes in Taxonomy in 1992.

Modified format by LRM in 8/2006 to include metric conversion and change permeability to saturated hydraulic conductivity.

In Nebraska, the native vegetative cover is an herbaceous wetland community commonly inhabited with sedges (Carex emoryi, C. laeviconica, C. pellita, C. vulpinoidea), flat stem spikerush, (Eleocharis compressa), Kentucky bluegrass (Poa Pratensis), prairie cordgrass (Spartina pectinate). Source: Terrestrial Ecological Systems and Natural Communities of Nebraska, Version IV. S.B. Rolfsmeier and G. Steinauer. Nebraska Natural Heritage Program, Nebraska Game and Parks Commission. 2010

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National Cooperative Soil Survey
U.S.A.