LOCATION TROSI CA+ID NV

Established Series
Rev. HRS/GMK/LCL/JBF
06/2017

TROSI SERIES

The Trosi series consists of shallow, well drained soils that formed in alluvium derived from mixed rocks. Trosi soils are on fan remnants. Slopes are 2 to 50 percent. The mean annual precipitation is about 230 mm and the mean annual soil temperature is about 9 degrees C.

TAXONOMIC CLASS: Clayey-skeletal, smectitic, mesic, shallow Xeric Argidurids

TYPICAL PEDON: Trosi very gravelly sandy loam - rangeland (Colors are for dry soil unless otherwise noted.) The surface is covered with 10 to 20 percent stones and cobbles.

A1--0 to 5 cm; light brown (7.5YR 6/4) very gravelly sandy loam, dark brown (7.5YR 3/4) moist; weak thick platy structure; slightly hard, very friable, nonsticky and nonplastic; many fine roots; few fine tubular, many very fine and fine vesicular pores; 30 percent gravel, 5 percent cobbles and 5 percent stones; slightly acid (pH 6.1); clear smooth boundary. (3 to 8 cm thick)

A2--5 to 18 cm; light brown (7.5YR 6/4) very gravelly sandy loam, dark brown (7.5YR 3/4) moist; weak thick platy structure; slightly hard, friable, slightly sticky and nonplastic; common very fine, few fine and medium roots; common very fine tubular and interstitial pores; 30 percent gravel, 5 percent cobbles and 5 percent stones; slightly acid (pH 6.1); clear smooth boundary. (8 to 15 cm thick)

Bt1--18 to 30 cm; brown (7.5YR 5/4) very cobbly sandy clay loam, dark reddish brown (5YR 3/4) moist; weak medium angular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine, few fine and medium roots; common very fine tubular and interstitial pores; common faint clay films line pores and as clay bridges between sand grains; 20 percent gravel, 20 percent cobbles and 1 percent stones; slightly acid (pH 6.1); clear smooth boundary. (8 to 18 cm thick)

Bt2--30 to 48 cm; brown (7.5YR 5/4) very cobbly clay, yellowish red (5YR 4/6) moist; weak coarse prismatic parting to weak fine and medium angular blocky structure; very hard, firm, moderately sticky and moderately plastic; common very fine, few fine and medium roots; few very fine tubular pores; continuous distinct clay films line pores and on faces of peds; 20 percent gravel, 20 percent cobbles and 1 percent stones; slightly acid (pH 6.1); abrupt smooth boundary. (13 to 25 cm thick)

Bqm--48 to 66 cm; light brown (7.5YR 6/4) and pink (7.5YR 7/4) gravelly indurated pan, strong brown (7.5YR 5/6) moist; massive; common prominent fine and medium black stains; continuous distinct clay films in fractures; slightly acid (pH 6.1).

2C--66 to 152 cm; stratified consolidated sediment.

TYPE LOCATION: Lassen County, California; 3/4 mile south and 2-1/4 mile west of Hallelujah Junction; 400 feet south of north quarter corner of sec. 16, T. 22 N., R. 17 E.; USGS Beckworth Pass 7.5 minute topographic quadrangle; latitude 39 degrees 45 minutes 54 seconds N and longitude 120 degrees 4 minutes 58 seconds W; WGS84 Decimal Degrees 39.7650000 latitude, -120.0827778 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually dry, moist in winter and early spring; aridic soil moisture regime bordering on xeric.
Mean annual soil temperature: 9 to 10 degrees C.
Depth to the indurated pan: 20 to 50 cm.

Particle-size control section - Clay content: 35 to 50 percent.
Rock fragments: 35 to 60 percent.

A horizon
Hue: 10YR or 7.5YR.
Chroma: 2 through 4.

Bt2 horizon
Hue: 10YR or 7.5YR dry, 5YR, 7.5YR or 10YR moist.
Value 3 or 4, moist.
Chroma: 3 or 4 dry, 3 through 6 moist.
Texture: Clay or clay loam.

COMPETING SERIES: These are the Ackett and Reina series.

Ackett soils are violently effervescent in the argillic horizon. Riena soils have hard bedrock at 56 to 76 cm.

GEOGRAPHIC SETTING: The Trosi soils are on fan remnants at elevations of 1,465 to 1,590 meters. Slopes are 2 to 50 percent. They formed in alluvium derived from mixed rocks. The climate is semiarid with warm dry summers and cold moist winters. Mean annual precipitation is 200 to 300 mm. Mean annual temperature is 9 to 10 degrees C. The freeze-free season is 60 to 90 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Reba soils and the Reno and Saralegui soils. Reno soils have less than 35 percent rock fragments in the particle-size control section. Saralegui soils have argillic horizons with less than 18 percent clay.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well-drained; slow to rapid runoff; very slow permeability; low saturated hydraulic conductivity.

USE AND VEGETATION: Used for rangeland. The vegetation is principally stunted big sagebrush, cheatgrass, and a few perennial grasses.

DISTRIBUTION AND EXTENT: Northeastern California. The soils are of small extent. MLRA 23 and 26.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California

SERIES ESTABLISHED: Lassen County, California, 1973.

REMARKS: The Trosi soils were formerly classified as Brown soils.

Diagnostic horizon and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 18 cm (A1 and A2 horizons).
Argillic horizon - The zone from 18 to 48 cm (Bt1 and Bt2 horizons).
Indurated duripan - The zone from 48 to 66 cm (Bqm horizon).
Particle size control section - The zone from 13 to 63 cm (Bt1, Bt2 and part of the Bt3 horizon).

National Cooperative Soil Survey
U.S.A.