LOCATION FORSGREN UTEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Vertic Argixerolls
TYPICAL PEDON: Forsgren silt loam, nonirrigated cropland. (Colors are for dry soil unless otherwise noted.)
Ap--0 to 5 inches; dark grayish brown (10YR 4/2) heavy silt loam, very dark brown (10YR 2/2) moist; weak medium subangular blocky structure that parts to weak medium granular structure; slightly hard, friable, nonsticky and slightly plastic; common fine roots; few fine pores; moderately acid (pH 6.0); clear smooth boundary. (4 to 6 inches thick)
A--5 to 8 inches; dark grayish brown (10YR 4/2) heavy silt loam, very dark brown (10YR 2/2) moist; weak medium and fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common fine roots; few fine pores; moderately acid (pH 6.0); gradual wavy boundary. (0 to 6 inches thick)
Bt1--8 to 16 inches; brown (10YR 4/3) silty clay loam, dark brown (7.5YR 3/2) moist; weak medium prismatic structure that parts to moderate medium or fine subangular blocky structure; very hard, firm, sticky and plastic; few fine roots; common fine pores; many thin clay films on faces of peds; moderately acid (pH 6.0); gradual wavy boundary. (6 to 10 inches thick)
Bt2--16 to 34 inches; brown (7.5YR 5/4) light silty clay, brown (7.5YR 4/4) moist; moderate coarse prismatic structure that parts to strong medium or coarse angular blocky structure; very hard, firm, sticky and very plastic; few fine roots; few fine pores; continuous thick clay films on faces of peds; neutral (pH 6.9); gradual wavy boundary. (14 to 24 inches thick)
Bt3--34 to 38 inches; brown (7.5YR 5/4) heavy silty clay loam, brown (7.5YR 4/4) moist; moderate coarse prismatic structure that parts to moderate medium subangular blocky structure; very hard, firm, sticky and very plastic; few very fine roots; few fine pores; many moderately thick clay films on faces of peds; slightly calcareous; slightly alkaline (pH 7.4); gradual wavy boundary. (0 to 10 inches thick)
Bt4--38 to 52 inches; light brown (7.5YR 6/4) silty clay loam, brown (7.5YR 4/4) moist; moderate coarse and fine subangular blocky structure; very hard, firm, sticky and very plastic; few very fine roots; few fine pores; many thin clay films on faces of peds; slightly calcareous; slightly alkaline (pH 7.5); gradual wavy boundary. (0 to 16 inches thick)
C--52 to 66 inches; light brown (7.5YR 6/4) silt loam, brown (7.5YR 5/4) moist; massive; hard, friable, slightly sticky and slightly plastic; moderately calcareous; slightly alkaline (pH 7.4).
TYPE LOCATION: Box Elder County, Utah; 8 miles north, 1 mile east from Pocatello Valley turn off Highway I-80N, at a point 850 feet east of the W1/4 corner of section 10, T.14N., R.5W.
RANGE IN CHARACTERISTICS: The soils are usually moist. They are moist in parts of the moisture control section for more than 1/2 the time the soil temperature is above 41 degrees F. The soil is dry in all parts of the moisture control section for 60 to 90 consecutive days during the summer temperature at 20 inch depth ranges from 68 to 70 degrees F.
The mollic epipedon is 10 to 19 inches thick. The solum is 40 to 55 inches thick. Some secondary carbonates occur in veins at depths of 40 to 55 inches. A few pebbles 1/4 to 3/4 inch in diameter are on the surface and at depths below 30 inches. Cracks 1/2 to 1 1/2 inches wide and extending to depths of over 20 inches occur during the summer when the soil is dry.
The A horizon has value of 4 or 5 dry, 2 or 3 moist. It is neutral to mildly alkaline and is 5 to 11 inches thick.
The Bt horizon has hue of 7.5YR or 10YR, value of 4 or 5 dry, 3 or 4 moist, and chroma of 2 or 3 but only the upper 6 to 10 inches of the B2t has hue of 10YR and value of 4 dry and 3 moist. It is clay or silty clay loam. It is 20 to 40 inches thick. It has common to continuous, thin to thick clay films on faces of peds.
The C or Ck horizon has hue of 7.5YR or 10YR, value of 6 or 7 dry, 4 or 5 moist, and chroma of 3 or 4. It is silt loam, silty clay loam or silty clay. It is moderately to strongly alkaline and is slightly to strongly calcareous at depths below 40 inches.
COMPETING SERIES: These are the Battle Creek, Gemson, Manila, McMurdie, Montour and Nebeker series. None of these soils except Battle Creek and Montour crack to depths of 20 inches. Battle Creek, McMurdie and Gemson soils have a calcic horizon within 40 inches. Manila soils have a mean annual temperature of less than 47 degrees F. Montour soils have argillic horizons with hue of 2.5Y or 5Y, and have calcic horizons at depths of less than 40 inches. Nebecker and McMurdie soils have a mollic epipedon more than 20 inches thick.
GEOGRAPHIC SETTING: Forsgren soils are at elevations of 5,175 to 5,500 feet on gently sloping to moderately steep mountain foot slopes and colluvial fans, and occur just above the highest terrace of old Lake Bonneville. Slopes are dominantly 10 to 20 percent and range from 1 to 20 percent. These soils formed in colluvium and residuum from sandstone, quartzite and some limestone rocks. The climate is dry subhumid, with an average annual precipitation ranging form 17 to 18 inches. The mean annual temperature ranges from 46 to 50 degrees F., and the mean summer temperature ranges from 66 to 69 degrees F. The frost free season is 100 to 120 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Broad, Hendricks, Parleys, and Sterling soils. Broad soils have gravelly amd cobbly clay loam argillic horizons with less than 35 percent clay and lime horizons within 40 inches. Hendricks soils have silty clay loam argillic horizons with less than 35 percent clay. Parleys soils have silty clay loam argillic horizons with less than 35 percent clay and have calcic horizons. Sterling soils have more than 50 percent coarse fragments in the control section and have calcic horizons.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; slow permeability.
USE AND VEGETATION: This soil is used mainly for nonirrigated cropland and some small areas of rangeland. Native vegetation is bluebunch wheatgrass, Great Basin wildrye grass, Sandberg bluegrass, big sagebrush, yellowbrush, yarrow, lupine and associated plants.
DISTRIBUTION AND EXTENT: Northern Utah. This soil is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Box Elder County (East Box Elder Area), Utah, 1969.