LOCATION MOONBEND CAEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, thermic Pachic Haploxerolls
TYPICAL PEDON: Moonbend silt loam - on a south facing slope of less than 1 percent in a prune orchard at an elevation of 50 feet. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 8 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine roots; common fine tubular pores; neutral (pH 7.1); clear smooth boundary. (8 to 35 inches thick)
Bw1--8 to 19 inches; grayish brown (10YR 5/2) silty clay loam, dark brown (10YR 3/3) moist; moderate medium prismatic parting to subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few very fine roots; common fine, medium and coarse and few very fine tubular pores; few thin silt coatings line pores; neutral (pH 7.0); clear smooth boundary. (8 to 25 inches thick)
Bw2--19 to 34 inches; grayish brown (10YR 5/2) silty clay loam, dark brown (10YR 3/3) moist; weak medium prismatic parting to moderate medium subangular blocky structure; very hard, friable, slightly sticky and slightly plastic; few very fine roots; many very fine and common fine and medium tubular pores; common thin silt coatings line pores; neutral (pH 7.2); clear smooth boundary.
Bw3--34 to 42 inches; grayish brown (10YR 5/2) loam, dark brown (10YR 3/3) moist; weak medium prismatic parting to moderate medium subangular blocky structure; very hard, friable, slightly sticky and slightly plastic; few very fine roots; many fine medium and common very fine tubular pores; neutral (pH 7.0); clear smooth boundary.
BC--42 to 52 inches; pale brown (10YR 6/3) silt loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; very hard, friable, slightly sticky and slightly plastic; few very fine roots; common fine and medium tubular pores; neutral (pH 7.0); clear smooth boundary.
C--52 to 64 inches; pale brown (10YR 6/3) silt loam, dark brown (10YR 3/3) moist; massive; hard, friable, slightly sticky and slightly plastic; few very fine roots; many very fine tubular pores; slightly effervescent; moderately alkaline (pH 7.9); clear smooth boundary.
Ab--64 to 76 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine tubular pores; slightly effervescent; moderately alkaline (pH 7.9); clear smooth boundary.
C'--76 to 86 inches; light yellowish brown (10YR 6/4) loam, dark brown (7.5YR 4/4) moist; massive; hard, friable, nonsticky and nonplastic; many very fine tubular pores; slightly effervescent; slightly alkaline (pH 7.7).
TYPE LOCATION: Colusa County, California; about 1.5 miles south east of Colusa CA; 1900 feet east and 450 feet north of the southwest corner of Sec. 33, projected, T. 16N., R. 1W;. 39 degrees 11 minutes 15 seconds North latitude, 121 degrees, 58 minutes, 45 seconds West longitud, USGS Meridian CA quadrangle.
RANGE IN CHARACTERISTICS: The solum ranges from 40 to 80 inches thick. Mean annual soil temperature is 63 to 65 degrees F and the soil temperature is not below 47 degrees F at any time. The soil between the depths of 6 and 17 inches is dry in all parts from May 15 to October 31 and moist in some or all parts from November 15 to May 1. Weighted average clay content of the 10 to 40 inch textural control section is 27 to 35 percent; fine sand or coarser ranges from 2 to 6 percent. The mollic epipedon is 25 to 42 inches thick.
The Ap horizon dry color is 10YR 5/2. Moist color is 10YR 3/3 or 3/2. Texture is loam or silt loam. Reaction is neutral.
The Bw horizon dry color is 10YR 6/3, 6/2, 5/3, or 5/2. Moist color is 10YR 4/3, 3/3 or 3/2. Texture is loam, silt loam, silty clay loam, or clay loam, with 18 to 35 percent clay. Reaction is neutral to moderately alkaline.
The C horizon dry color is 10YR 6/4, 6/3, or 5/3. Moist color is 10YR 4/4, 4/3, 3/3, or 7.5YR 4/4. Texture is loam, silt loam, silty clay loam, or clay loam. Reaction is slightly alkaline to moderately alkaline.
COMPETING SERIES: These are the Corval, Coyotecreek, Crowhill, Horst and Suey series. Corval soils are well drained and non-stratified, lack temporary water tables, and are non effervescent. Coyotecreek, Horst and Suey soils have 18 to 27 percent clay in the particle size control section. Crowhill soil have a paralithic contact at 20 to 40 inches.
GEOGRAPHIC SETTING: Moonbend soils are on high flood plains. Slopes are 0 to 2 percent. Elevation is 45 to 60 feet. These soils formed in mixed alluvium. The climate is subhumid with hot dry summers and cool moist winters with frequent fogs. Mean annual precipitation is 14 to 16 inches. Mean January temperature is about 45 degrees F; mean July temperature is about 78 degrees F; mean annual temperature is 60 to 62 degrees F. Frost-free season is 225 to 250 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are Vina and Corbiere soils. Vina soils have coarse-loamy particle-size control sections and lack subsoil development. Corbiere(T) soils have fine particle-size control sections.
DRAINAGE AND PERMEABILITY: Moderately well drained; negligable to low runoff; moderately slow permeability. Improvement of drainage in this soil has occurred due to levees and other flood control structures on the Sacramento River. Areas adjacent to river levees have temporary water tables at 3 to 6 feet when water levels in the river are high.
USE AND VEGETATION: This soil is used for irrigated crops and orchards. Among the crops commonly grown are tomatoes, beans, prunes and walnuts. Native vegetation in areas not cropped is oaks, willows, wild grapes, annual grasses and herbs.
DISTRIBUTION AND EXTENT: Flood plains of the Sacramento River and tributary streams in the lower Sacramento Valley, California. The soils are moderately extensive. MLRA is 17.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Colusa County Soil Survey, California, 1997. Source of name is a local name for a nearby bend in the river.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
Mollic epipedon -- the zone from the soil surface to about 42 inches (Ap, Bw1, Bw2, Bw3).
Cambic horizon -- the zone from about 42 to 52 inches (BC); a structural cambic.
Thin sections (NSSL 89PO619 R7123) from the Bw2 horizon show some weak grain argillans; PSDA shows no significant increase in clay content from Ap to Bw1 and no significant increase in the ratio of fine clay to total clay in the profile. Amount and distribution of fine and very fine sand (as a percent of sand plus silt) in the profile suggest numerous minor lithologic discontinuities.
Pachic subgroup -- organic carbon content decreases regularly with increasing depth and is greater than .6 percent to 51 inches.
ADDITIONAL DATA: This pedon has complete laboratory characterization. NSSL sample number S89CA-011-002 (89P 63).