LOCATION ARGOVAR CAEstablished Series
TAXONOMIC CLASS: Fine-loamy over clayey, mixed, superactive, thermic Typic Argiaquolls
TYPICAL PEDON: Argovar silt loam - or a west facing slope of 1 percent under annual grasses, sedges and rushes at 2,155 feet elevation. (Colors are for dry soil unless otherwise stated. When described on May 28, 1986, the soil was moist throughout and saturated at 45 inches.)
A--0 to 8 inches; brown (10YR 5/3) silt loam, dark brown (10YR 3/3) moist; many fine prominent yellowish red (5YR 5/8) mottles, red (2.5YR 4/6, 4/8) moist; weak fine granular structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and common fine roots; common very fine and fine tubular and few very fine interstitial pores; 5 percent pebbles; slightly acid (pH 6.5); abrupt smooth boundary. (4 to 10 inches thick)
2Ab--8 to 17 inches; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; many fine prominent strong brown (7.5YR 4/6) mottles, (7.5YR 4/4) moist; weak fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; common very fine and few fine tubular pores; 2 percent pebbles; neutral (pH 6.8); clear smooth boundary. (8 to 12 inches thick)
2Btb1--17 to 26 inches; brown (10YR 5/3) clay loam, dark brown (10YR 3/3) moist; common medium prominent yellowish brown (10YR 5/6) mottles, dark yellowish brown (10YR 4/6) moist; moderate medium subangular blocky structure; hard, very friable, sticky and plastic; common very fine and fine roots; common very fine and fine tubular pores; common thin clay films in pores and on ped faces; 2 percent pebbles; neutral (pH 7.0); abrupt smooth boundary. (8 to 12 inches thick)
3Btb2--26 to 44 inches; olive (5Y 5/3) clay, olive (5Y 4/3) moist; many medium prominent yellowish brown (10YR 5/6) and dark greenish gray (5GY 4/1) mottles in root channels, surrounding pebbles and in part of matrix; massive; very hard, firm, very sticky and very plastic; common very fine roots; few very fine tubular pores; common slickensides; 5 percent gabbro diorite pebbles, and 5 percent gabbriorite cobbles, some concentrated at upper boundary as a stone line; neutral (pH 7.0); gradual smooth boundary. (16 to 22 inches thick)
3Btb3--44 to 55 inches; pale yellow (5Y 7/4) clay, pale olive (5Y 6/4) moist; common medium prominent brownish yellow (10YR 6/8) and few fine prominent light gray (5Y 6/1) mottles, yellowish brown (10YR 5/6) and gray (5Y 5/1) moist; massive; very hard, firm, very sticky and very plastic; common very fine roots; few very fine tubular pores; few slickensides; neutral (pH 7.0); gradual smooth boundary. (4 to 20 inches thick)
3BCb--55 to 62 inches; reddish yellow (7.5YR 6/8) clay, strong brown (7.5YR 5/8) moist; common medium prominent light yellowish brown (2.5Y 6/4) mottles, olive (5Y 5/3) moist; massive; very hard, friable, very sticky and very plastic; few clean quartz sand grains; neutral (pH 7.0).
TYPE LOCATION: Yuba County, California; about 4.5 miles south of Brownsville on Willow Glen Road, then 800 feet northwest on dirt road, across from Willow Glen Ranch, 2,400 feet south of the northeast corner sec. 16, T. 18 N., R. 6 E. Rackerby quadrangle.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 59 to 60 degrees F. The soil temperature is below 47 degrees F from January 15 to February 15. The soil is saturated to the surface, probably by the capillary fringe at least part of the time in October thru May. Mottles with chroma of 4,6 or 8 occur throughout.
The A and 2Ab horizons have dry color of 10YR 5/3, 5/2, 4/1, or 5Y 4/1, and moist colors of 7.5YR 3/2, 10YR 2/1, 3/1, 3/2, 3/3, or 5Y 4/1. Reaction is slightly acid or neutral. Base saturation is 50 to 75 percent.
The 2Bt horizon has dry color of 10YR 5/3, 4/1 or 5Y 4/1 and moist colors of 10YR 2/1, 3/2, 3/2, 3/4 or 7.5YR 3/2. It is loam or clay loam with 20 to 30 percent clay. Reaction is neutral. Base saturation is 50 to 75 percent.
The 3Bt horizon has dry color of 5Y 5/1, 5/2, 5/3, and moist color of 5Y 4/1, 4/2, 4/3, or 6/4. It has dry color in the lower part of 7.5YR 6/8, 10YR 5/6, 5Y 5/8, 5/6, 4/4, 7/4 and moist color of 7.5YR 5/8, 10YR 4/6, 5Y 4/8, 4/6, 4/4, 6/4. It has mottles with chroma of 1. Clay content ranges from 45 to 60 percent. There is a 25 to 35 percent absolute clay increase from the 2Bt to the 3Bt horizon. Reaction is neutral. Base saturation is 75 to 90 percent.
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: Argovar soils are in mountain meadows and have slopes of 0 to 5 percent. The soils formed in material from gabbrodiorite. The A, 2Ab, and 2Bt horizons are slope alluvium deposited on the 3B horizons which weathered from parent rock. A stone line separates the two layers. Elevations range from 2,000 to 2,500 feet. The climate is characterized by hot dry summers and cool moist winters. Mean annual precipitation is 30 to 40 inches. The mean January temperature is 46 degrees F; mean July temperature is 79 degrees F; mean annual temperature is 58 to 61 degrees F. Frost-free season is 220 to 235 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Verjeles, Flanly and Surnuf soils. They lack a water table and are on slopes above the Argovar soils. Verjeles, and Flanly soils have a paralithic contact at 20 to 40 inches. Surnuf soils are mesic.
DRAINAGE AND PERMEABILITY: Poorly drained; slow runoff; very slow permeability. A water table is at 24 to 48 inches in October to May.
USE AND VEGETATION: Used for livestock grazing and wildlife habitat. Natural vegetation is annual grasses, sedges and rushes.
DISTRIBUTION AND EXTENT: Western Sierra Nevada Foothills, California. This series is not extensive. MLRA is 18.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Yuba County, California, l988.
REMARKS: The activity class was added to the classification in January of 2003. Competing series were not checked at that time. - ET
Major Diagnostic Horizons:
1. Mollic epipedon - 0 to 26 inches (A, 2Ab, 2Btb)
2. Argillic horizon - 17 to 55 inches (2Btb, 3Btb1, 3Btb2)
2.1 Percent Clay content by hydrometer method as follows: A-22, 2Ab-22, 2Btb1-27, 3Btb2-57, 3Btb3-55.
Last revised by the state on 10/92.