LOCATION MALLARD CAEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, thermic Pachic Argixerolls
TYPICAL PEDON: Mallard clay loam, 0 to 1 percent slopes. When described on July 1, 1987 the soil was dry to 3 inches and moist below to a water table at 50 inches. (Colors are for dry soil unless otherwise stated)
Ap--0 to 3 inches; dark grayish brown (10YR 4/2) clay loam, very dark grayish brown (10YR 3/2) moist; strong medium granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine interstitial pores; neutral (pH 6.8); clear smooth boundary. (3 to 18 inches thick)
Bt1--3 to 8 inches; dark grayish brown (10YR 4/2) clay loam, very dark grayish brown (10YR 3/2) moist; strong medium subangular blocky structure; hard, friable, sticky and slightly plastic; common very fine roots; few very fine interstitial pores; many moderately thick clay films on ped faces and bridging sand grains; neutral (pH 7.0); gradual smooth boundary.
Bt2--8 to 15 inches; dark grayish brown (10YR 4/2) clay; very dark grayish brown (10YR 3/2) moist; strong medium subangular blocky structure; very hard, friable, sticky and slightly plastic; common very fine roots; few very fine interstitial pores; many moderately thick clay films on ped faces and bridging sand grains; neutral (pH 7.2); clear smooth boundary.
Bt3--15 to 28 inches; brown (10YR 4/3) clay; dark brown (10YR 3/3) moist; weak medium subangular blocky structure; very hard, friable, slightly sticky and slightly plastic; few very fine roots; few very fine tubular and interstitial pores; common thin clay films bridging sand grains and on ped faces; slightly alkaline (pH 7.4); clear smooth boundary. (combined thickness of the Bt horizons is 15 to 33 inches thick)
C1--28 to 44 inches; brown (10YR 5/3) clay loam; brown (10YR 4/3) moist; weak medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few very fine roots; many very fine tubular pores; slightly alkaline (pH 7.8); effervescent, disseminated lime; clear smooth boundary.
C2--44 to 60 inches; yellowish brown (10YR 5/4) clay loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; hard, friable, slightly sticky and slightly
plastic; few very fine roots; many very fine tubular and few fine tubular pores; few fine prominent grayish brown (10YR 5/2) masses of iron depletions; moderately alkaline(pH 8.0); strongly effervescent with segregated lime in seams and disseminated lime.
TYPE LOCATION: Colusa County, California; about 1.5 miles southeast of Williams CA; 1000 feet west, 1000 feet south of the north east corner of section 19, T. 15 N., R. 2 W., MDB&M; 39 degrees, 8 minutes, 38 seconds north latitude and 122 degrees, 7 minutes, 7 seconds west longitude; USGS Colusa CA quadrangle.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 63 to 65 degrees F. The soil temperature is above 47 degrees F. the entire year. The soil moisture control section of 5 to 15 inches is dry in all parts from May 15 to October 31 unless irrigated and is moist in some or all parts from November 1 to May 15.
The A horizon has dry color of 10YR 5/3, 5/2, 4/3 or 4/2 and moist color of 10YR 3/3 or 3/2. Texture is clay loam or loam. Reaction is slightly acid to moderately alkaline.
The Bt horizon has dry color of 10YR 5/3, 5/2, 4/4, 4/3 or 4/2 and moist color of 10YR 4/4, 4/3, 3/4 or 3/3. Texture is clay or clay loam. Reaction is neutral to moderately alkaline. The weighted average clay content of the textural control section, the upper 20 inches of the Bt, is 35 to 45 percent.
The C horizon has a dry color of 10YR 5/4, 5/3, 4/3 or 5Y 5/2 and moist color of 10YR 4/4, 4/3, 3/3 or 5Y 4/2. Texture is clay loam or loam. Reaction is slightly to moderately alkaline.
COMPETING SERIES: This is the Cole series. Cole soils have a difference in mean summer and mean winter temperatures of 16 to 23 degrees. Cole soils are dry in the moisture control section for 90 days and developed under 25 to 50 inches of precipitation.
GEOGRAPHIC SETTING: Mallard soils are on alluvial fans at elevations of 30 to 1300 feet. The soils formed in mixed alluvium. The climate has hot dry summers and cool moist winters with frequent fog. Mean annual precipitation varies from 14 to 22 inches. Average January temperature is about 44 degrees F; average July temperature is about 78 degrees F. Mean annual temperature is 58 to 62 degrees F. The frost-free season is 185 to 250 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Capay, Hustabel, Willows and Westfan soils.. Capay soils are in basins and are fine textured. Hustabel soils have coarse loamy control sections. Willows soils are in basins and have fine textures. Westfan soils have fine loamy control sections.
DRAINAGE AND PERMEABILITY: somewhat poorly drained; negligable to medium runoff; slow permeability. High water tables occur from 3 to 6 feet from November through April.
USE AND VEGETATION: used for cropland in the Sacramento Valley. Native vegetation is annual grasses and forbs.
DISTRIBUTION AND EXTENT: Alluvial fans on the western lower Sacramento Valley. The soils are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Colusa County SSA, California, Colusa
Soil Survey 1997.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
1. Mollic epipedon 0 to 28 inches ranges from 20 to 35
or more inches thick - pachic.
1.1 O.M. assumed to be greater than 1%.
2. Argillic horizon ranges from 15 to 33 inches thick.
3. Fine Family: The textural control section, the top 20" of the argillic, is 8 to 28 inches.
3.1 Soil PSA done locally by 6 hour hydrometer
method:
Horizon Depth Sand Silt Clay.
(in.)
Ap 0-3 26 40 34
B 3-8 26 38 36
Bt1 8-15 26 32 42
Bt2 15-28 22 38 40
C1 28-44 26 44 30
C2 44-60 28 42 30
Weighted average clay content of the 8 to 28 inch
textural control section is 40.7.
Other diagnostic horizons or soil characteristics:
1. Temperature/moisture class (thermic-xeric)
1.1 SMCS, 7 to 20 inches is dry in all parts from
May 15 to Oct. 31 and is moist in all parts
from Nov. 15 to May 1 and the soil temp-
erature is above 47 degrees for the entire year
1.2 MAST is 63 to 65 F.
2. Mixed mineralogy is assumed, based on lab data
of closely associated soils with similar
characteristics.