LOCATION LAWTHER                 ND+MT SD

Established Series
Rev. CJH
01/2023

LAWTHER SERIES

The Lawther series consists of very deep, well drained, slowly permeable soils that formed in calcareous clayey sediments. These soils are on uplands, fans and terraces. Slope ranges from 0 to 9 percent. Mean annual air temperature is 42 degrees F, and mean annual precipitation is 16 inches.

TAXONOMIC CLASS: Fine, smectitic, frigid Typic Haplusterts

TYPICAL PEDON: Lawther silty clay - on an east facing concave slope of 2 percent in a cultivated field. (When the soil was sampled it was moist throughout. Colors are for dry soil unless otherwise stated.)

Ap--0 to 4 inches; dark grayish brown (2.5Y 4/2) silty clay, very dark grayish brown (2.5Y 3/2) moist; weak medium and coarse subangular blocky structure parting to moderate medium granular; very hard, firm, sticky and very plastic; common very fine pores; slightly alkaline; abrupt smooth boundary.

A--4 to 10 inches; dark grayish brown (2.5Y 4/2) silty clay, very dark grayish brown (2.5Y 3/2) moist; moderate coarse subangular blocky structure; very hard, very firm, sticky and very plastic; common very fine roots; common very fine pores; slightly alkaline; clear wavy boundary. (Combined A horizons 4 to 12 inches thick)

Bss1--10 to 21 inches; grayish brown (2.5Y 5/2) silty clay, dark grayish brown (2.5Y 4/2) moist; weak coarse prismatic structure parting to moderate fine and medium subangular blocky; very hard, firm, very sticky and very plastic; common very fine roots; common very fine pores; very dark grayish brown (2.5Y 3/2) moist coatings on faces of peds; 1 inch wide cracks filled with A horizon material; common slickensides; very slight effervescence; slightly alkaline; gradual wavy boundary.

Bss2--21 to 33 inches; grayish brown (2.5Y 5/2) silty clay, dark grayish brown (2.5Y 4/2) moist; weak coarse and medium subangular blocky structure parting to moderate fine subangular blocky; very hard, firm, very sticky and very plastic; few very fine roots; common very fine pores; 1/2 inch wide cracks filled with A horizon material; common slickensides; few medium irregularly shaped masses of carbonates; strong effervescence; moderately alkaline; clear wavy boundary. (Combined Bss horizons 5 to 25 inches thick)

Bk--33 to 47 inches; light brownish gray (2.5Y 6/2) silty clay, dark grayish brown (2.5Y 4/2) moist; weak coarse subangular blocky structure; very hard, firm, very sticky and very plastic; few very fine roots; common very fine pores; 1/2 inch wide cracks filled with A horizon material; common slickensides; common fine irregularly shaped masses of carbonates; strong effervescence; moderately alkaline; abrupt wavy boundary. (0 to 24 inches thick)

C--47 to 60 inches; grayish brown (2.5Y 5/2) clay loam, dark grayish brown (2.5Y 4/2) moist; weak coarse prismatic structure; very hard, firm, very sticky and very plastic; few very fine roots; many very fine pores; common fine irregularly shaped masses of carbonates; strong effervescence; moderately alkaline.

TYPE LOCATION: Adams County, North Dakota; about 3 miles north and 3 miles east of Reeder; 2,195 feet south and 1,440 feet east of the northwest corner, sec. 25, T. 131 N., R. 98 W.

RANGE IN CHARACTERISTICS: The mollic epipedon ranges from 7 to more than 20 inches in thickness. Many pedons contain carbonates to the surface, but some do not have carbonates to depths of 30 inches. When the soil is dry, cracks 1/2 to 2 inches wide and several feet long extend downward through the solum. Typically, the series control section averages between 45 to 60 percent clay, 30 to 55 percent silt and less than 10 percent sand.

The A horizon has hue of 10YR or 2.5Y, value of 3 to 5 and 2 or 3 moist, and chroma of 2. It typically is silty clay, but it is clay or silty clay loam in some pedons. It is neutral to moderately alkaline.

The Bss horizon has hue of 10YR, 2.5Y or 5Y, value of 3 to 6 and 2 to 4 moist, and chroma of 1 to 3. It is clay, silty clay or silty clay loam. It is slightly alkaline to strongly alkaline.

The Bk horizon has hue of 2.5Y or 5Y, value of 4 to 6 and 2 to 5 moist, and chroma of 1 or 2. It is silty clay, clay or silty clay loam. It is moderately alkaline or strongly alkaline. It contains gypsum in some pedons. Some pedons have a BCk horizon.

Some pedons have a By horizon up to 15 inches thick. It has hue of 10YR, 2.5Y, 5Y or is neutral, value of 4 to 6 and 2 to 5 moist, and chroma of 3 or less. It is silty clay, clay or silty clay loam. It is moderately alkaline or strongly alkaline.

The C horizon has hue of 2.5Y or 5Y, value of 4 to 7 and 3 to 6 moist, and chroma of 1 to 3. It is clay loam, silty clay, clay or silty clay loam. It is stratified or laminated in some pedons. It is moderately alkaline or strongly alkaline. Some pedons have thin strata of coarser textures below a depth of 40 inches. Some pedons have gypsum in the C horizon.

COMPETING SERIES: This is the Wildrose series. Wildrose series averages more than 10 percent sand in the series control section.

GEOGRAPHIC SETTING: Lawther soils are on level to sloping uplands, fans and terraces. Slopes are plane or slightly concave. Slope gradients typically range from 0 to 4 percent, but some are as steep as 9 percent. The soil formed in calcareous clayey sediments. The climate is cool, semiarid. Mean annual air temperature ranges from 39 to 45 degrees F, and mean annual precipitation from 13 to 19 inches. Most of the precipitation comes in the spring and summer.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Grail, Moreau, Morton, Regent, Wyola and Sen soils. Grail and Wyola soils are in swales and on terraces. They have Bt horizons which average between 35 and 45 percent clay. Moreau, Morton, Regent and Sen soils are on the nearby upland plains. These soils have soft bedrock at depths of 20 to 40 inches. In addition, Morton and Sen soils have less than 35 percent clay in the particle-size control section.

DRAINAGE AND PERMEABILITY: Well drained. Surface runoff is slow or medium. Permeability is slow.

USE AND VEGETATION: Most areas are cropped to wheat and other small grains. Some is in native grass. Native vegetation includes western wheatgrass, green needlegrass, blue grama, and 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: Bowman County, North Dakota, August 1969.

REMARKS: Revised 5/94.

Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of 10 inches (Ap and A horizons); Vertisol criteria - slickensides and cracks filled with A horizon material 1/2 to 1 inch wide in the zone from 10 to 47 inches (Bss1, Bss2 and Bk horizons) and 45 to 60 percent clay throughout the particle-size control section.

ADDITIONAL DATA: S77ND001-006 and S77ND001-006A - Typical Pedon; S64ND011-001; S64ND011-005; S78ND037-011; S90ND105-266; and S90ND105-267.

---

National Cooperative Soil Survey
U.S.A.