LOCATION THURLOW MTEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Torrertic Haplustalfs
TYPICAL PEDON: Thurlow clay loam - native grass cover. (Colors are for dry soil unless otherwise noted)
A--0 to 4 inches; grayish brown (10YR 5/2) heavy loam, dark grayish brown (10YR 4/2) moist; weak thin platy structure in the upper part and moderate thin structure in the lower part; slightly hard, friable, slightly sticky, slightly plastic; many very fine roots; many clear unstained sand grains on tops of plates; clear smooth boundary. (2 to 6 inches thick)
Bt--4 to 16 inches; brown (10YR 5/3) heavy clay loam, brown (10YR 4/3) moist; dark grayish brown (10YR 4/2) coating on peds, dark brown (10YR 3/3) moist; moderate medium prismatic structure that separates to strong medium blocks; very hard, firm, sticky, plastic; common very fine roots; many very fine and common fine tubular pores; varnish-like coating on peds and on walls of pores and root channels, with some pores having rounded edges; maximum clay content is in the upper part of the horizon; clear boundary. (6 to 16 inches thick)
Bk--16 to 28 inches; light yellowish brown (2.5Y 6/3) clay loam, light olive brown (2.5Y 5/3) moist; prisms coated slightly darker in the upper part; moderate medium prismatic grading to weak coarse prismatic structure that separates to weak coarse blocks; hard, friable, sticky, plastic; common very fine roots; common very fine and fine tubular pores; calcareous with common films of segregated lime; gradual boundary. (8 to 20 inches thick)
C--28 to 60 inches; light yellowish brown (2.5Y 6/3) stratified clay loam and clay, light olive brown (2.5Y 5/3) moist; massive; hard, friable, sticky plastic; few very fine roots; common very fine tubular pores; calcareous.
TYPE LOCATION: Yellowstone County, Montana; 1,200 feet north of SE corner section 19, T.2N., R.28E.
RANGE IN CHARACTERISTICS: Thurlow soils are usually dry when not frozen unless irrigated and they have mean annual soil temperature of 47 to 5O degrees F. The nonclacareous part of the solum is 10 to 20 inches thick.
The A horizon has hue lOYR or 2.5Y, value of 5 or 5.5 dry and 3.5 or 4 moist, and chroma of 2 or 3. In its upper part coated colors are one unit of value less than when crushed and less than that of the A horizon. It is silt loam, silty clay loam or clay loam.
The Bt horizon has hue of 10YR or 2.5Y, dry value of 4 or 5 coated and 5 or 6 crushed, moist value of 4 or 5 crushed, and chroma of 2 to 4. It contains 35 to 45 percent clay and has 6 to 10 percent more clay than the A horizon and is highest in clay in the upper part.
COMPETING SERIES: These are the Demar, Horselake, Moorhead and Teeque series. Demar soils are more acid and have a Bz horizon. Horselake soils are moderately deep. Moorhead soils have a Btk horizon and are warmer. Teeque soils are dry during the period of April through June.
Baca, Bew, Fort Collins, Hesper and Renohill series. Baca and Hesper soils have less than 18 percent fine and coarser sand in their pedons. Bew soils have 50 to 60 percent clay in their Bt horizons. Fort Collins soils have less than 35 percent clay in the Bt horizon. Renohill soils have shale bedrock at depths of about 30 inches.
GEOGRAPHIC SETTING: The Thurlow soils are in valleys on river and stream terraces. The soil formed in calcareous, clay loam, unconsolidated materials. Slopes are 0 to 15 percent. Climate is cool semiarid with mean annual air temperature of 45 to 48F., mean summer temperature of more than 62F., and winter temperature 20 to 28F. Mean annual precipitation is l0 to 13 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arvada, Bew, Fort Collins and Hydro soils. Arvada and Hydro soils have natric horizons. Bew soils have 50 to 60 percent clay in their Bt horizons. Fort Collins soils have less than 35 percent clay in the Bt horizon.
DRAINAGE AND PERMEABILITY: Well-drained; moderately permeable.
USE AND VEGETATION: Used mainly for irrigated production of diversified crops, nonirrigated production of small grains and native range of mid and short grasses. Potential native vegetation is mainly blue grama and western wheatgrass.
DISTRIBUTION AND EXTENT: Thurlow series is moderately extensive in southeastern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado.
SERIES ESTABLISHED: Big Horn County (Big Horn Area), Montana, 1970.
REMARKS: 4/2002 revisions largely to correct errors in OSED scan by NSSQA and update the "Competing Series" section.
An analysis of the series in 1999 indicated the series may be frigid. It also indicated the series could possibly be included with the Pinehill series.
SIR- MT0492