LOCATION MOREAU ND+MT SD
Established Series
Rev. CJH
01/2023
MOREAU SERIES
The Moreau series consists of moderately deep, well or moderately well drained, slowly permeable soils that formed in soft calcareous alkaline shales. These soils are on sedimentary upland plains and have slopes ranging from 0 to 40 percent. Mean annual air temperature is 42 degrees F and mean annual precipitation is 15 inches.
TAXONOMIC CLASS: Fine, smectitic, frigid Vertic Haplustolls
TYPICAL PEDON: Moreau silty clay - on an north facing plane slope of 1 percent under cropland. (Colors are for dry soils unless otherwise stated)
Ap--0 to 6 inches; dark grayish brown (2.5Y 4/2) silty clay, very dark grayish brown (2.5Y 3/2) moist; weak fine granular structure; slightly hard, friable, very sticky and very plastic; few very fine roots; slight effervescence; slightly alkaline; abrupt wavy boundary. (4 to 10 inches thick)
Bw--6 to 13 inches; light olive brown (2.5Y 5/3) silty clay, olive brown (2.5Y 4/3) moist; weak coarse prismatic structure parting to moderate medium subangular blocky; very hard, firm, very sticky and very plastic; few very fine roots; 1 to 2 inch wide cracks filled with A material throughout; strong effervescence; slightly alkaline; clear wavy boundary. (0 to 20 inches thick)
Bk--13 to 27 inches; light yellowish brown (2.5Y 6/3) silty clay, light olive brown (2.5Y 5/3) moist; weak coarse prismatic structure parting to weak medium subangular blocky; slightly hard, firm, very sticky and very plastic; 1 to 2 inch wide cracks filled with A material in upper 10 inches; common medium irregularly shaped masses of carbonates; violent effervescence; moderately alkaline; gradual wavy boundary. (0 to 25 inches thick)
BCk--27 to 35 inches; light brownish gray (2.5Y 6/2) silty clay, dark grayish brown (2.5Y 4/2) moist; weak medium subangular blocky structure; slightly hard, firm, very sticky and very plastic; common olive yellow (2.5Y 6/6) iron stains; about 50 percent fine fragments of unweathered shale; few medium irregularly shaped masses of carbonates; strong effervescence; moderately alkaline; gradual wavy boundary. (0 to 14 inches thick)
Cr--35 to 60 inches; light olive gray (5Y 6/2) soft shale, olive gray (5Y 4/2) moist; common olive yellow (2.5Y 6/6) iron stains between bedrock laminations; slight effervescence; moderately alkaline.
TYPE LOCATION: Sioux County, North Dakota; about 29 miles south and 1 mile east of New Leipzig; 350 feet north and 200 feet east of the southwest corner, sec. 22, T. 129 N., R. 90 W.
RANGE IN CHARACTERISTICS: The soil typically contains 2 to 15 percent calcium carbonate equivalent. Depth to carbonates ranges form 0 to 10 inches. When the soil is dry, cracks 1/2 to 2 inches wide and several feet long extend from the surface to a depth of 20 to 30 inches. The depth to soft shale ranges from 20 to 40 inches. The soil above the soft shale bedrock is slightly alkaline to strongly alkaline. Saline phases are recognized.
The A horizon has hue of 10YR or 2.5Y, value of 4 or 5 and 2 or 3 moist. It is silty clay, clay, silty clay loam or clay loam.
The Bw horizon has hue of 10YR, 2.5Y or 5Y, value of 5 or 6 and 3 to 5 moist, and chroma of 2 to 4. It is silty clay, clay or silty clay loam. It typically averages between 45 and 55 percent clay but ranges from 35 to 60 percent. It has weak or moderate grades of prismatic structure parting to weak to strong subangular or angular blocky.
The Bk and BCk horizons have hue of 2.5Y or 5Y, value of 5 or 6 and 4 or 5 moist, and chroma of 1 to 3. They are silty clay, clay or silty clay loam and have 35 to 60 percent clay. They contain nests of gypsum in some pedons. Some pedons have a By horizon with properties similar to the Bk and BCk horizons.
Some pedons have a C horizon up to 12 inches thick. Where present, it has hue of 2.5Y or 5Y, value of 5 to 7 and 4 to 6 moist, and chroma of 2 to 4. It is clay, silty clay or silty clay loam and has 35 to 60 percent clay. It commonly has few to many gypsum crystals and carbonates disseminated or in masses. It has an EC of 2 to 16 mmhos/cm and ESP of 4 to 12.
The Cr material has hue of 5Y or 2.5Y, value of 5 to 7 and 3 to 6 moist, and chroma of 2 to 4. It typically is platy. It is laminated in some pedons and massive in others. It commonly has nests or lenses of gypsum and is moderately or strongly alkaline.
COMPETING SERIES: These are the
Lawther and
Tomty series. These soils do not have a paralithic contact within a depth of 40 inches. In addition, Tomty soils are somewhat poorly drained and have a chroma of 1 in the upper 18 cm.
GEOGRAPHICAL SETTING: Moreau soils are on level to very steep sedimentary upland plains. Slope gradients commonly are 2 to 5 percent, but range from 0 to 40 percent. The soils formed in soft calcareous, alkaline shales. The climate is cool, semiarid. The mean annual air temperature ranges from 39 to 45 degrees F and the mean annual precipitation ranges from 12 to 20 inches. Most of the precipitation occurs in the spring and summer.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing
Lawther soils and the
Cabba,
Daglum,
Dimyaw,
Grail,
Morton,
Regent,
Wyola,
Sen,
Rhoades and
Wayden soils. Lawther and Wyola soils are on level concave swales and terraces. Dimyaw and Wyola soils do not have a paralithic contact within 40 inches. Wayden soils have a paralithic contact within 20 inches. Dimyaw and Wayden soils are on crests of hills and steep slopes. Regent soils have an argillic horizon and are on similar landscapes with Moreau soils. Cabba, Morton, and Sen soils are on nearby uplands. Cabba soils have bedded siltstone at shallow depths and are on steep slopes. Morton and Sen soils are fine-silty. Daglum and Rhoades soils have a natric horizon. They are on nearby uplands and terraces, and are in complex with Moreau soils in some areas. Grail soils are in nearby concave swales. They have a mollic epipedon more than 16 inches thick.
DRAINAGE AND PERMEABILITY: Well or moderately well drained. Runoff is negligible to very high depending on surface texture and slope. Permeability is slow.
USE AND VEGETATION: Soils are cropped to small grains, and used for range and pasture. Native vegetation is western wheatgrass, blue grama, green needlegrass and a variety of forbs.
DISTRIBUTION AND EXTENT: Southwestern North Dakota, northwestern South Dakota and eastern Montana. The soil is extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Salina, Kansas
SERIES ESTABLISHED: Wibaux County, Montana, 1956.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of 7 inches (after mixing) (Ap horizon); cambic horizon - the zone from 7 to 13 inches (Bw horizon); vertic subgroup criteria - cracks 1 to 2 inches wide extending to a depth of 23 inches when the soil is dry, and 35 to 60 percent clay throughout.
ADDITIONAL DATA: S54NDak-21-2 in Soil Survey Investigation Report No. 2, pp. 194-195.
National Cooperative Soil Survey
U.S.A.