LOCATION CHAQUA CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, thermic Typic Calcixerepts
TYPICAL PEDON: Chaqua loam - on an east-facing slope of 4 percent, under soft chess, filaree and other annual grasses and forbs at an elevation of 520 feet. (Colors are for dry soil unless otherwise stated. When described on June 2, l978, the soil was dry to 6 inches and slightly moist below.)
A--0 to 6 inches; light yellowish brown (10YR 6/4) loam, dark brown (7.5YR 3/4) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, moderately sticky and slightly plastic; many very fine roots; few very fine and fine tubular pores; 2 percent gravel, 2 to 15 mm in size; slightly effervescent, carbonates disseminated; moderately alkaline (pH 8.0); clear smooth boundary. (5 to 8 inches thick)
Btk1--6 to 19 inches; yellowish brown (10YR 5/4) loam, strong brown (7.5YR 4/6) moist; weak, fine and medium subangular blocky structure; slightly hard, very friable, moderately sticky and moderately plastic; many very fine roots; common very fine and fine tubular pores; common thin clay films line pores; 2 percent gravel, 2 to 15 mm in size; strongly effervescent, carbonates disseminated and segregated as few fine threads; calcium carbonate equivalent is 12 percent; moderately alkaline (pH 8.0); gradual smooth boundary. (6 to 14 inches thick)
Btk2--19 to 25 inches; brown (7.5YR 5/4) loam, strong brown (7.5YR 4/6) moist; weak, fine and medium subangular blocky structure; slightly hard, very friable, moderately sticky and moderately plastic; common very fine roots; common very fine and fine tubular pores; many thin clay films on faces of peds and in peds and in pores; 2 percent gravel, 2 to 15 mm in size; violently effervescent, carbonates disseminated and segregated as few fine threads; calcium carbonate equivalent is 15 percent; moderately alkaline (pH 8.0); clear smooth boundary. (5 to 9 inches thick)
Btk3--25 to 35 inches; brown (7.5YR 5/4) loam, strong brown (7.5YR 4/6) moist; weak fine and medium subangular blocky structure; soft, very friable, moderately sticky and moderately plastic; common very fine roots; common very fine and fine tubular pores; many thin clay films on faces of peds and in pores; 2 percent gravel, 2 to 15 mm in size; violently effervescent, carbonates disseminated and segregated as few fine threads; calcium carbonate equivalent is 18 percent; moderately alkaline (pH 8.0); clear smooth boundary. (8 to 15 inches thick)
Btk4--35 to 47 inches; strong brown (7.5YR 5/6) loam, strong brown (7.5YR 4/6) moist; weak fine and medium subangular blocky structure; soft, friable, moderately sticky and moderately plastic; common very fine roots; common very fine and fine tubular pores; common thin clay films on faces of peds, many thin clay films in pores; 10 percent gravel, 2 to 15 mm in size; strongly effervescent, carbonates disseminated; calcium carbonate equivalent is 10 percent; moderately alkaline (pH 8.0); abrupt smooth boundary. (10 to 19 inches thick)
2Cr--47 to 50 inches; strongly weathered calcareous sandstone.
TYPE LOCATION: Merced County, California; approxmately 9 miles southwest of the city of Los Banos; 1,200 feet south and 700 feet west of the northeast corner of section 26, T. 11 S., R. 9 E., MDB&M; Latitude 36 degrees, 57 minutes, 06 seconds north and Longitude 120 degrees, 56 minutes, 50 seconds west; USGS Ortigalita Peak NW Topographic Quadrangle, NAD27.
RANGE IN CHARACTERISTICS: Depth to a paralithic contact is 40 to 60 inches. The mean annual soil temperature is 61 degrees to 65 degrees F. The soil temperature is below 47 degrees F in parts of January and February and is never below 41 degrees F at any time. The soil between the depths of 6 and 18 inches is moist throughout from January 1 to May 1 and dry throughout from July 1 to November 1. Reaction is slightly alkaline or moderately alkaline throughout.
The A horizon has color of 10YR 4/4, 5/2, 5/3, 5/4, 6/2, 6/4; 7.5YR 4/6 or 5/4. Moist color is 10YR 4/2, 4/3, 5/4, 6/2; 7.5YR 3/4 or 4/6. Clay content is 18 to 27 percent. Calcium carbonate equivalent is 5 to 15 percent. Gravel content is 0 to 10 percent. Some pedons have a Bk horizon just below the A horizon.
The Btk horizon has color of 10YR 5/4, 6/2, 6/3, 6/4, 7/4; 7.5YR 4/4, 5/4, 5/6, 6/4 or 6/6. Moist color is 10YR 4/2, 4/3, 4/4, 5/6, 6/2, 6/4, 6/6; 7.5YR 3/4, 4/4, 4/6, 5/4 or 5/6. Texture is loam, clay loam, or sandy clay loam. Clay content is 18 to 30 percent but is never 1.2 times greater than the A horizon. Calcium carbonate equivalent is 10 to 25 percent. Gravel content is 0 to 15 percent. Cobble content is 0 to 5 percent.
COMPETING SERIES: These are the Balcom (CA) and Calla (CA) series. Balcom soils (MLRA 15, 20), on hills, have a paralithic contact at a depth of 20 to 40 inches. Calla soils (MLRA 17), on dissected and uplifted terraces, are very deep.
GEOGRAPHIC SETTING: Chaqua soils are on uplifted and dissected terraces and stream terraces. Slope is 2 to 15 percent. These soils formed in calcareous alluvium from sedimentary and igneous sources. Elevation is 300 to 1,200 feet. The climate is semiarid with hot dry summers and cool moist winters. The mean annual precipitation is 9 to 13 inches. The mean January temperature is 46 degrees F; mean July temperature is 78 degrees F. and the mean annual temperature is 60 to 64 degrees F. The frost-free season is 200 to 280 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bapos, Damluis, Herito and Los Banos soils. Bapos soils on terraces and fan remnants, are very deep and have a fine particle-size control section. Damluis, Herito and Los Banos soils, on terraces, are very deep, have an argillic horizon and a fine particle-size control section.
DRAINAGE AND PERMEABILITY: Well drained; low or medium runoff; moderately slow permeability.
USE AND VEGETATION: These soils are used for livestock grazing and dryland barley production. Where irrigation water is available, they are used for irrigated cotton. The vegetation is soft chess, filaree, purple needlegrass, foxtail fescue, wild oats, red brome, filaree, tarweed and other annual grasses and forbs.
DISTRIBUTION AND EXTENT: These soils are on the western edge of the San Joaquin Valley. They are not extensive. MLRA-17.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Merced County, California, 1984.
REMARKS: These soils were mapped as Kettleman and Los Banos in the Los Banos Area, series 1939 report. They are being differentiated from the Kettleman series by having a paralithic contact at 40 to 60 inches, and from the Los Banos series by having a fine-loamy control section and not having an argillic horizon.
Diagnostic horizons and features recognized in this pedon are:
Ochric Epipedon - The zone from 0 to 19 inches (A, Btk1horizons)
Cambic Horizon - The zone from 6 to 19 inches (Btk1 horizon)
Calcic Horizon - The zone from 19 to 35 inches (Btk2, Btk3 horizons). The Merced County, Western Part Soil Survey database should reflect the calcium carbonate equivalent percent for the A and Btk1 horizons as 5 to 15 percent and for the Btk2, Btk3 and Btk4 horizons as 10 to 25 percent. Calcium carbonate equivalent percent was not an entry on the SCS-5 when this soil survey was completed.
CEC/Clay ratio estimated from similar soils with laboratory data in the W. Stanislaus Soil Survey Area.