LOCATION BRONCHO ID+OR UTEstablished Series
TAXONOMIC CLASS: Sandy-skeletal, mixed, mesic Xeric Haplocambids
TYPICAL PEDON: Broncho gravelly loam - on rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 6 inches; light brownish gray (10YR 6/2) gravelly loam, very dark grayish brown (10YR 3/2) moist; weak very thin platy structure parting to weak very fine granular; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine vesicular pores; 20 percent gravel; moderately alkaline (pH 8.0); clear smooth boundary. (3 to 8 inches thick)
Bw--6 to 14 inches; light brownish gray (10YR 6/2) gravelly loam, dark grayish brown (10YR 4/2) moist; weak medium platy and coarse subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine tubular pores; 20 percent gravel; slightly effervescent; gravel slightly lime coated on lower side; moderately alkaline (pH 8.3); clear wavy boundary. (6 to 13 inches thick)
Bk1--14 to 17 inches; white (10YR 8/2) extremely gravelly coarse sandy loam, pale brown (10YR 6/3) moist; massive; hard, firm, nonsticky and nonplastic; many very fine roots; many very fine tubular pores; 45 percent gravel and 15 percent cobbles; strongly effervescent; weakly cemented in places; moderately thick lime coatings on the lower sides of gravel and thin coatings on the upper sides of gravel; strongly alkaline (pH 8.6); abrupt irregular boundary. (0 to 5 inches thick)
2Bk2--17 to 25 inches; multicolored extremely gravelly coarse sand; single grained; loose, nonsticky and nonplastic; few very fine roots; 45 percent gravel and 15 percent cobbles; strongly effervescent; weakly cemented in places; thick coatings of lime on underside of gravel; strongly alkaline (pH 8.6); gradual irregular boundary.
2Bk3--25 to 60 inches; multicolored extremely gravelly coarse sand; single grained; loose, nonsticky and nonplastic; few roots; 50 percent gravel and 20 percent cobbles; slightly effervescent; thin lime coatings on underside of gravel; strongly alkaline (pH 8.6).
TYPE LOCATION: Power County, Idaho; center of southeast 1/4, northwest 1/4, section. 2, T. 6 S., R. 33 E.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 47 to 52 degrees F.
Depth to loose sand and gravel - 10 to 20 inches
A horizon
Value - 4 through 7 dry, 3 through 5 moist
Chroma, dry or moist - 2 or 3
Reaction - slightly to strongly alkaline
Bw horizon
Value - 6 or 7 dry, 3 to 5 moist
Chroma, dry or moist - 2 to 4
Reaction - mildly to moderately alkaline
Texture - L, SL, COSL
Coarse fragments - 15 to 60 percent mixed gravel, cobbles, and stones
Bk horizon
When present this horizon is less than 6 inches thick.
Value - 6 through 8 dry, 5 through 7 moist
Chroma, dry or moist - 1 through 3
Reaction - moderately to strongly alkaline
Texture - L, SL, COSL, COS
Coarse fragments - 35 to 65 percent mixed gravel, cobbles, and stones
It has 5 to 20 percent calcium carbonate.
2Bk horizon
Texture - COS, S, LCOS
Coarse fragments - 35 to 85 percent mixed gravel, cobbles, and stones
It has 0 to 15 percent calcium carbonate.
COMPETING SERIES: These are the Malaga, McConnel, McNye, McWatt, and Ragnel series. Malaga soils lack carbonates. McConnel soils have lexss than 5 percent calcium carbonate throughout. McNye and McWatt soils have bedrock at 40 to 60 inches. Ragnel soils receive 10 to 20 days of precipitation between July and October.
GEOGRAPHIC SETTING: Broncho soils are on terraces and fans. Slopes range from 0 to 40 percent. They formed in mixed alluvium, dominantly from quartzite, limestone, and sandstone materials. The average annual precipitation ranges from 8 to 12 inches, and the average annual temperature ranges from 46 to 51 degrees F. The frost-free season is about 90 to 130 days. Elevation ranges from 1,600 to 4,500 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bahem, Broxon, Chedehap, Declo, and Paniogue soils. Bahem soils are coarse-silty and are calcareous to the surface. Broxon soils have contrasting particle-size control sections at moderate depths and are calcareous to the surface. Chedehap soils are coarse-loamy and have loose sand at moderate depths. Declo soils are coarse-loamy and are calcareous to the surface. Paniogue soils have contrasting particle-size control sections at moderate depths. Bahem, Broxon, Declo, and Paniogue soils are on the flatter terrace summits. Chedehap soils are on narrow ridges on alluvial terraces.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; slow to very rapid runoff; moderate permeability in the upper part and very rapid in the substratum.
USE AND VEGETATION: Used for irrigated pasture and cropland and as rangeland. The potential natural vegetation is mainly Wyoming big sagebrush, bluebunch wheatgrass, Sandberg bluegrass, and Thurber needlegrass.
DISTRIBUTION AND EXTENT: Southeastern Idaho, central Oregon. MLRA 10, 11, 28A. The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Fort Hall Area, Idaho, 1973.
REMARKS: Diagnostic horizons and other features:
Ochric epipedon
Cambic horizon - 6 to 14 inches
The zone of maximum calcium carbonate accumulation Bk1 horizon is too thin to qualify for calcic horizon and in some pedons is absent.