LOCATION HILLGATE CAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Typic Palexeralfs
TYPICAL PEDON: Hillgate loam, on an east facing slope of 3 percent in rangeland at an elevation of 140 feet. (Colors are for dry soil unless otherwise stated.)
A1--0 to 3 inches; yellowish brown (10YR 5/4) loam; dark yellowish brown (10YR 4/4) moist; moderate medium subangular blocky structure; hard, friable, slightly sticky, and slightly plastic; common very fine roots; common very fine tubular pores; few fine distinct light brownish gray (10YR 6/2) iron depletions; slightly acid (pH 6.2); abrupt smooth boundary.
A2--3 to 11 inches; yellowish brown (10YR 5/4) loam; dark yellowish brown (10YR 4/4) moist; strong medium angular blocky structure; hard, friable, slightly sticky, and slightly plastic; common very fine roots; common very fine and few fine tubular pores; common fine distinct light brownish gray (10YR 6/2) iron depletions moderately acid (pH 5.6); clear smooth boundary.
A3--11 to 19 inches; yellowish brown (10YR 5/4) loam; dark yellowish brown (10YR 4/4) moist; strong medium angular blocky structure; hard, friable, slightly sticky, and slightly plastic; few very fine roots; common very fine and few fine tubular pores;common fine faint very pale brown (10YR 7/3) iron depletions; moderately acid (pH 5.6); abrupt smooth boundary.
2Bt1--19 to 38 inches; yellowish brown (10YR 5/4) clay; dark yellowish brown (10YR 3/4) moist; strong coarse prismatic structure; extremely hard, firm, moderately sticky and moderately plastic; few very fine roots; common very fine and few fine tubular pores; many moderately thick clay films; slightly acid (pH 6.2); clear smooth boundary.
2Bt2--38 to 53 inches; yellowish brown (10YR 5/4) clay loam; dark yellowish brown (10YR 3/4) moist; strong coarse prismatic structure; extremely hard, firm, sticky, and plastic; few very fine roots; common very fine tubular pores; many moderately thick clay films; neutral (pH 7.2); clear smooth boundary.
2Bt3--53 to 63 inches; yellowish brown (10YR 5/4) clay loam;, dark yellowish brown (10YR 3/4); moderate medium subangular blocky structure; very hard, firm, sticky, and plastic; few very fine roots; common very fine tubular pores; many moderately thick clay films; slightly alkaline (pH 7.5); clear smooth boundary.
2Bt4--63 to 73 inches; yellowish brown (10YR 5/4) clay loam; dark yellowish brown (10YR 3/4) ; moderate medium subangular blocky structure; very hard, firm, sticky, and plastic; few very fine roots; common very fine tubular pores; many moderately thick clay films; slightly alkaline (pH 7.4).
TYPE LOCATION: Colusa County, California; about 4.5 miles west of Maxwell; 2,400 feet south and 2,500 feet east of the northwest corner of sec. 2, T. 16 N., R. 4 W., MDB&M; 39 degrees, 16 minutes, 10 seconds North Latitude and 121 degrees, 16 minutes, 20 seconds West Longitude, USGS Sites CA quadrangle.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 63 to 65 degrees F and the soil temperature is not below 47 at any time. The soil between the depths of 6 and 18 inches is dry in all parts from May 15 to October 31 and moist in some or all parts from November 1 to May 15. Weighted average clay content for the 19 to 39 inch textural control section ranges from 35 to 50 percent clay. The solum ranges from 60 to 75 inches thick.
The A horizon has dry color of 10YR 7/2, 6/4, 6/3, 6/2, 5/4, 5/3; 7.5YR 5/4, 4/4 and moist color of 10YR 5/3, 4/4, 4/3, 3/4, 3/3; 7.5YR 4/4, 3/4. Texture is very fine sandy loam, loam, silt loam or clay loam. Reaction is strongly to slightly acid.
The Bt horizon has dry color of 10YR 6/6, 6/3, 5/8, 5/6, 5/4, 5/3; 7.5YR 5/8, 5/6, 5/5, 5/4, 4/6 and moist color of 10YR 5/6, 5/4, 4/6, 4/4, 4/3, 3/4, 3/3; 7.5YR 5/4, 5/6, 4/6, 4/4, 4/3, 3/4. Texture is clay loam or clay. Reaction is slightly acid to moderately alkaline.
COMPETING SERIES: These are the
Cometa,
Corning,
Hytop,
Millsap,
Orognen,
San Ysidro and
Yokayo series. Cometa has a solumn thickness of 24 to 40 inches and the Bt includes 5YR colors. The Corning series has Bt colors of 2.5YR or 5YR. The Hytop series has a paralithic contact at 20 to 40 inches. Millsap has a lithic contact at 20 to 40 inches. Orognen has 5YR Bt colors. Yokayo has a solumn thickness of 30 to 50 inches, mean annual air temperature of 57 degrees F. and precipitation of 32 to 44 inches.
Hillgate needs to be competed with San Ysidro during MLRA update. The soils are the same, but Hillgate is mapped on slopes of 0 to 50 percent. The San Ysidro is mapped on 0 to 9 percent slopes and may need to be combined with Hillgate on 0 to 9 percent slopes.
Colusa County holds the Hillgate type location which was lab sampled. In Colusa the Hillgate is mapped on 0 to 9 percent slopes. The Hillgate on 9 to 50 percent slopes (in Eastern
Santa Clara County) would then be a new series.
GEOGRAPHIC SETTING: Hillgate soils are on nearly level to moderately sloping old terraces at elevations of 15-2,000 feet. The soils formed in alluvium from mixed rock sources. The climate is semiarid to subhumid with hot dry summers and cool moist winters. Mean annual precipitation varies from 14 to 30 inches. Mean annual air temperature ranges from 58 to 65 degrees F. Average January temperature is about 44 degrees and the average July temperature is about 80 degrees F. Average frost free season is about 185 to 300 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arbuckle, Corning, Kimball, Myers, Tehama, San Ysidro and Zamora soils. Arbuckle, Tehama and Zamora soils all have less than 35 percent clay in the argillic horizon. Kimball soils have a mollic epipedon. Myers soils are fine textured throughout.
DRAINAGE AND PERMEABILITY: Well to moderately well drained. negligable to very high runoff, very slow and slow permeability.
USE AND VEGETATION: Where cultivated, small grains, irrigated pasture, shallow rooted row crops and rice. Areas not cultivated, annual grasses and forbs with open stands of valley and blue oaks.
DISTRIBUTION AND EXTENT: West side of Sacramento Valley and Coast Range valleys, soils are of moderate extent. MLRA 15, 14 and into MLRA 17.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Tehama County, California, 1962.
REMARKS:
Major Diagnostic Horizons:
1. Ochric Epipedon - 0 to 19 inches; (A1, A2, A3) Ranges
from 11 to 24 inches thick.
1.1 Chromas are 4 or Values are 6 or more.
1.2 Organic matter is 0.5 percent or less below 3
inches.
2. Argillic horizon - 19 to 73 inches; (2Bt1, 2Bt2, 2Bt3,
2Bt4)
2.1 Many moderately thick clay films.
2.2 Clay increase exceeds 1.2 times the A horizon.
2.3 PSA by Lincoln NSSL:
HORIZON DEPTH CLAY SILT SAND
(in.)
A1 0-3 17.9 38.8 43.3
A2 3-11 19.5 37.3 43.2
A3 11-19 21.4 35.9 42.7
2Bt1 19-38 42.5 27.1 30.4
2Bt2 38-53 36.4 31.0 32.6
2Bt3 53-63 34.6 31.7 33.7
2Bt4 63-73 34.1 29.8 36.1
Other Diagnostic Horizons or Soil Characteristics:
1. Pale great group - Abrupt boundary at 19 inches has more
than a 20 percent absolute increase in clay within a
vertical distance of 3 inches.
2. Smectitic family - lab data indicates mineralogy
is smectitic, superactive.
3. Temperature - Moisture (Xeric-thermic)
3.1 The 6 to 18 inch SMCS is dry in all parts from May 15
to October 31 and is moist in all parts from November
15 to May 1.
3.2 The Soil temperature is above 47 degrees F. for the
entire year.
3.3 The MAST is 63 to 65 degrees F.
ADDITIONAL DATA: NSSL sample # S89CA-011-006 Pedon No. 89P-193 and pedons S89CA-103-005 (taxadjunct) and S89CA-103-006