LOCATION RIDGELAWN MT+ND WYEstablished Series
TAXONOMIC CLASS: Fine-loamy over sandy or sandy-skeletal, mixed, superactive, calcareous, frigid Typic Ustifluvents
TYPICAL PEDON: Ridgelawn silt loam - cultivated. (Colors are for dry soil unless otherwise stated)
Ap--0 to 9 inches; light brownish gray (2.5Y 6/2) silt loam, dark grayish brown (2.5Y 4/2) moist; moderate coarse subangular blocky structure parting to moderate medium granular; hard, friable, slightly sticky and slightly plastic; common very fine roots throughout; slightly effervescent throughout (HCI, 1 normal); moderately alkaline (pH 8.0); abrupt boundary. (5 to 10 inches thick).
C1--9 to 20 inches; light brownish gray (2.5Y 6/2) stratified silt loam, dark grayish brown (2.5Y 4/2) moist; massive; hard, friable, moderately sticky and moderately plastic; stratifications 1 to 2 mm thick; common very fine roots throughout; common fine irregular yellowish brown (10YR 5/6) iron concretions pedogenic throughout; slightly effervescent throughout (HCI, 1 normal); moderately alkaline; clear smooth boundary.
C2--20 to 25 inches; light brownish gray (2.5Y 6/2) stratified silty clay loam, dark grayish brown (2.5Y 4/2) moist; massive; hard, friable, moderately sticky and moderately plastic; stratifications 1 to 2 mm thick; few very fine roots throughout; few irregular yellowish brown (10YR 5/6) iron concretions pedogenic throughout; strongly effervescent throughout (HCI, 1 normal); moderately alkaline; clear smooth boundary.
C3--25 to 29 inches; light brownish gray (2.5Y 6/2) stratified loam and silt loam, dark grayish brown (2.5Y 4/2) moist; massive; hard, friable, moderately sticky and moderately plastic; stratifications 1 to 2 mm thick; few very fine roots throughout; strongly effervescent throughout (HCI, 1 normal); moderately alkaline; abrupt smooth boundary. (Combined C horizons 10 to 35 inches thick)
2C4--29 to 49 inches; light brownish gray (2.5Y 6/2) fine sand, dark grayish brown (2.5Y 4/2) moist; single grain; loose, nonsticky and nonplastic; stratifications 1 to 2 mm thick; organic matter or coal strata 1 mm thick throughout; slightly effervescent throughout (HCI, 1 normal); moderately alkaline; abrupt smooth boundary.
2C5--49 to 57 inches; light brownish gray (2.5Y 6/2) stratified loamy fine sand, grayish brown (2.5Y 5/2) moist; single grain; loose, nonsticky and nonplastic; stratifications 1 to 2 mm thick; slightly effervescent throughout (HCI, 1 normal); moderately alkaline; clear smooth boundary.
2C6--57 to 70 inches; light brownish gray (2.5Y 6/2) stratified loamy sand, grayish brown (2.5Y 5/2) moist; single grain; loose, nonsticky and nonplastic; stratifications 1 to 2 mm thick; slightly effervescent throughout (HCI, 1 normal); moderately alkaline; clear smooth boundary.
2C7--70 to 80 inches; light brownish gray (2.5Y 6/2) sand, grayish brown (2.5Y 5/2) moist; single grain; loose, nonsticky and nonplastic; strata of coal 1-5 mm thick throughout; very slightly effervescent throughout (HCI, 1 normal); moderately alkaline.
TYPE LOCATION: Richland County, Montana, 2500 feet north and 140 feet east of the southwest corner, sec. 6, T. 21 N., R. 59 E.
RANGE IN CHARACTERISTICS: The soil has hue of 5Y, 2.5Y or 10YR; value is 5 or 6 dry, 4 or 5 moist, and chroma is 1 to 3 throughout. Average texture of the upper C horizons is loam, silt loam or silty clay loam with 18 to 35 percent clay and 15 to 35 percent fine sand and coarser. The 2C horizon occurs at depths of 20 to 40 inches. Texture of the sandy horizons is fine sand, loamy sand or loamy fine sand containing up to 35 percent gravel. Textures of sand are allowed below depths of 40 inches.
COMPETING SERIES: There are no competing series in the same family.
GEOGRAPHIC SETTING: Ridgelawn soils are on nearly level and gently sloping or undulating floodplains and low terraces. The soils formed in calcareous, loamy alluvium deposited over sandy alluvium that is gravelly in some areas. Mean annual temperature is 40 to 45 degrees F., mean January temperature is 8 to 25 degrees F., and mean July air temperature is 65 to 70 degrees F. Average annual precipitation is 10 to 16 inches. The frost-free period is 105 to 135 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Banks, Havrelon, Hoffmanville, Lohler and Trembles soils. Banks soils have sandy control sections. Havrelon, Lohler, and Trembles soils have fine loamy, fine, and coarse-loamy control sections respectively. Hoffmanville soils have clayey over sandy or sandy-skeletal control sections.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderate in upper part and rapid permeability in underlying material. Some areas are subject to occasional flooding.
USE AND VEGETATION: Ridgelawn soils are used mainly as dry farmed and irrigated cropland. Sugar beets, corn silage, alfalfa, and small grains are the main crops. Some areas are used as rangeland. Native vegetation is mainly green needlegrass, western wheatgrass, rosebush, snowberry, and silver sagebrush with a sparse overstory of cottonwood and green ash trees in some places.
DISTRIBUTION AND EXTENT: Eastern Montana. The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Richland County, Montana, 1973.
REMARKS: Diagnostic horizons and features recognized in this pedon are: irregular decrease in organic carbon - stratifications throughout C horizons.