LOCATION RONAN MTEstablished Series
TAXONOMIC CLASS: Very-fine, illitic, frigid Typic Natrixeralfs
TYPICAL PEDON: Ronan silty clay loam, cultivated (colors are for dry soil unless otherwise noted)
Ap--0 to 4 inches; light brownish gray (10YR 6/2) silty clay loam, very dark grayish brown (10YR 3/2) moist; moderate thin platy structure; soft, very friable, slightly sticky and slightly plastic; many very fine roots; few very fine pores; neutral (pH 7.2); abrupt wavy boundary. (3 to 6 inches thick)
Btn1--4 to 7 inches; pinkish gray (7.5YR 6/2) clay, brown (7.5YR 4/2) moist; strong coarse columnar structure parting to strong coarse and medium angular blocky; extremely hard, very firm, very sticky and very plastic; few very fine roots; many very fine pores; common distinct clay films on faces of peds; moderately alkaline (pH 8.4); abrupt wavy boundary. (2 to 5 inches)
Btn2--7 to 16 inches; pinkish gray (7.5YR 6/2) clay, brown (7.5YR 4/2) moist; strong coarse and medium angular blocky structure; very hard, very firm, very sticky and very plastic; few very fine roots; many very fine pores; common distinct clay films on faces of peds; strongly alkaline (pH 8.6); clear irregular boundary. (7 to 12 inches thick)
Bkn--16 to 24 inches; pinkish white (7.5YR 8/2) and pinkish gray (7.5YR 6/2) clay, brown (7.5YR 5/2) moist; massive; 1/4- to 1/2-inch thick varves; very hard, firm, very sticky and very plastic; few very fine pores; disseminated lime and few to common fine threads and masses of lime between varves; strongly effervescent; strongly alkaline (pH 8.8); gradual irregular boundary. (6 to 10 inches thick)
C--24 to 60 inches; pinkish white (7.5YR 8/2) and pinkish gray (7.5YR 6/2) clay, brown (7.5YR 5/2) moist; massive; 1/4- to 1/2-inch thick varves; very hard, firm, very sticky and very plastic; disseminated lime; strongly effervescent; strongly alkaline (pH 8.6).
TYPE LOCATION: Lake County, Montana; 1,110 feet south and 110 feet west of the NE corner of sec. 23, T. 19 N., R. 21 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 47 degrees F.
Moisture control section - between 4 and 12 inches.
Control section - 60 to 80 percent clay.
Depth to Bk horizon - 12 to 22 inches.
Depth to varves - 18 to 33 inches.
Ap horizon - Hue: 7.5YR or 10YR
Value: 6 or 7 dry, 3 or 4 moist
Chroma: 2 or 3
Texture: silty clay loam
Clay content: 30 to 40 percent
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles, 0 to 10 percent pebbles
SAR: 2 to 8
Reaction: pH 6.6 to 7.8
Btn1 horizon - Hue: 10YR or 7.5YR
Value: 6, 7, or 8 dry; 4, 5, or 6 moist
Chroma: 2, 3, or 4
Texture: clay
Clay content: 55 to 70 percent
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles, 0 to 10 percent pebbles
SAR: 6 to 13
Reaction: pH 7.4 to 8.4
Btn2 horizon - Hue: 10YR or 7.5YR
Value: 6, 7, or 8 dry; 4, 5, or 6 moist
Chroma: 2, 3, or 4
Texture: clay
Clay content: 60 to 80 percent
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles, 0 to 10 percent pebbles
EC: 0 to 4 mmhos/cm
SAR: 13 to 22
Reaction: pH 8.4 to 9.0
Bkn horizon - Hue: 10YR or 7.5YR
Value: 6, 7, or 8 dry; 4, 5, or 6 moist
Chroma: 2, 3, or 4
Texture: silty clay or clay
Clay content: 50 to 75 percent
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles, 0 to 10 percent pebbles
Calcium carbonate equivalent: 8 to 15 percent
EC: 2 to 8 mmhos/cm
SAR: 8 to 30
Reaction: pH 8.4 to 9.0
C horizon - Hue: 10YR or 7.5YR
Value: 6, 7, or 8 dry; 4, 5, or 6 moist
Chroma: 2, 3, or 4
Texture: silty clay or clay
Clay content: 50 to 75 percent
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles, 0 to 10 percent pebbles
Calcium carbonate equivalent: 8 to 15 percent
EC: 2 to 8 mmhos/cm
SAR: 2 to 8
Reaction: pH 8.4 to 9.0
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: The Ronan soils are on dissected lake plains. Elevations are 2,500 to 3,200 feet. Slopes are 0 to 15 percent. These soils formed in clayey lacustrine or glaciolacustrine deposits. The climate is characterized by long, cold winters; moist springs; and warm, dry summers. Mean annual precipitation is 12 to 16 inches. Mean annual temperature is 40 to 45 degrees F. The frost-free period is 105 to 130 days.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; very slow permeability.
USE AND VEGETATION: Ronan soils are used mainly for irrigated crops, dryland crops, and for pastureland. Potential native vegetation is mainly western wheatgrass, bluebunch wheatgrass, and Idaho fescue.
DISTRIBUTION AND EXTENT: Ronan soils are of moderate extent in the mountain valleys of northwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Lake County, Montana, 1991; proposed in Lake County, Montana, 1965. Ronan is a place name.
REMARKS: Soil Interpretation Records: MT0040. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 4 inches (Ap horizon); a natric horizon from 4 to 20 inches (Btn1, Btn2, and part of Bkn horizons); a horizon of lime accumulation (Bkn1 horizon); and a particle-size control section from 4 to 16 inches (Btn and Btn2 horizons). Ronan soils have a frigid temperature regime and a xeric moisture regime.
LABORATORY DATA: S85MT-047-475; S65MT-047-1.