LOCATION KIMBALL CAEstablished Series
TAXONOMIC CLASS: Fine, mixed, active, thermic Mollic Palexeralfs
TYPICAL PEDON: Kimball loam - on an east facing slope of about 1 percent under annual grasses and forbs at 100 feet elevation. (Colors are for dry soil unless otherwise noted.)
Ap1--0 to 2 inches; brown (7.5YR 4/4) loam, dark brown (7.5YR 3/4) moist; moderate medium and fine granular structure; soft, friable, nonsticky and nonplastic; many very fine roots; many very fine tubular pores; slightly acid; abrupt smooth boundary. (2 to 3 inches thick)
Ap2--2 to 4 inches; brown (7.5YR 4/4) loam, dark brown (7.5YR 3/4) moist; massive; hard, friable, nonsticky and nonplastic; many very fine roots; common fine and medium and many very fine tubular pores; slightly acid (pH 6.3); abrupt wavy boundary. (2 to 3 inches thick)
Ap3--4 to 6 inches; brown (7.5YR 4/4) loam, dark brown (7.5YR 3/4) moist; moderate thin platy structure; hard, friable, nonsticky and nonplastic; common very fine roots; many fine tubular pores; slightly acid (pH 6.2); clear smooth boundary. (0 to 3 inches thick)
A--6 to 10 inches; brown (7.5YR 4/4) loam, dark brown (7.5YR 3/4) moist; massive; hard, friable, nonsticky and nonplastic; many very fine roots; many fine tubular pores; slightly acid (pH 6.3); clear smooth boundary. (3 to 12 inches thick)
BAt--10 to 17 inches; reddish brown (5YR 4/4) loam, dark reddish brown (5YR 3/4) moist; massive; hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine and few fine pores; few thin brown clay films line pores; slightly acid (pH 6.3); abrupt wavy boundary. (0 to 8 inches thick)
2Btss1--17 to 34 inches; reddish brown (5YR 4/4) clay, reddish brown (5YR 4/4) moist; moderate coarse prismatic structure parting to strong coarse angular blocky; extremely hard, very firm, sticky and very plastic; common very fine exped roots; common very fine tubular pores; moderately thick continuous clay films on faces of peds and lining pores and as bridges; few slickensides; neutral (pH 6.6); gradual wavy boundary. (12 to 20 inches thick)
2Bt--34 to 46 inches; brown (7.5YR 5/4) sandy clay loam, reddish brown (5YR 4/4) moist; massive; very hard, firm, slightly sticky and slightly plastic; few very fine roots; many very fine tubular pores; moderately thick nearly continuous clay films lining pores; few black stains; neutral (pH 7.1); diffuse irregular boundary. (10 to 14 inches thick).
2BC--46 to 64 inches; brown (7.5YR 5/4) sandy clay loam, dark brown (7.5YR 3/4) moist; massive; hard, firm, slightly sticky and slightly plastic; few roots; many very fine tubular pores; neutral (pH 6.8). (0 to 20 inches thick)
TYPE LOCATION: Butte County, California; about 2 miles northwest of Honcut, about 0.3 miles south of the intersection of Central House Road and the railroad track, then about 100 feet west of the westerly edge of the railroad right-of-way in a small basin; about 1,850 feet south and 2,050 feet west of the northeast corner of sec. 7, T. 17 N., R. 4 E., MDBM, 39 degrees, 20 minutes, 49 seconds north latitude and 121 degrees, 33 minutes, 46 seconds west longitude, NAD 27 U.S.G.S. Quad: Honcut, California.
RANGE IN CHARACTERISTICS: Depth is greater than 80 inches. Unless irrigated, the soil between depths of 5 and 15 inches is moist in all parts from December to late April and is dry in all parts from June 1 thru October 15. The mean annual soil temperature is 60 degrees to 65 degrees F.
The Ap and A horizon has dry colors of 10YR 6/4, 6/3, 5/4, 5/3, 5/2, 4/4, 4/3; 7.5YR 5/4, 5/2, 4/4 or 4/2 and moist color of 10YR 3/2, 3/3, 3/4, 3/6; 7.5YR 3/4, or 3/2. It is sandy loam, loam or gravelly loam with 10 to 25 percent clay and 0 to 20 percent gravel. It is massive and hard when dry in some or all parts. Organic matter is 1.2 to 3 percent in the upper part and decreases to less than 1 percent in the lower part. Reaction is moderately acid to neutral.
The BAt horizon has dry colors of 10YR 6/4, 6/3; 7.5YR 6/4, 5/4, 4/4 or 5YR 4/4 and moist color of 10YR 4/4, 4/3, 3/3; 7.5YR 4/4, 5YR 4/4, 4/3 or 3/4. It is loam, clay loam, gravelly clay loam with 20 to 30 percent clay and 0 to 20 percent gravel. Reaction is moderately acid to neutral. Some pedons lack a BAt horizon.
The 2Btss and 2Bt horizon has dry colors of 10YR 6/4, 5/6, 5/4, 5/2, 7.5YR 6/4, 5/6, 5/4, 4/6, 4/4; 5YR 5/6, 5/4, 4/6 or 4/4 and moist color of 10YR 4/6, 4/4; 7.5YR 4/6, 4/4, 3/4, 5YR 4/6, 4/4, 4/3 or 3/4. It is clay loam, clay, gravelly clay loam or gravelly clay with 35 to 60 percent clay and 0 to 20 percent gravel. It has an abrupt upper boundary with an absolute clay increase of 15 to 30 percent more than the overlying horizon. Reaction is moderately acid to neutral.
The 2B horizon has dry colors of 10YR 7/4, 6/4, 6/3, 7.5YR 5/6, 5/4, 5YR 5/6, 5/4 or 4/4 and moist color of 10YR 5/4, 7.5YR 4/6, 4/4, 5YR 4/6 or 4/4. It is sandy loam, loam, sandy clay loam, clay loam or their gravelly equivalents with 20 to 40 percent clay and 0 to 35 percent gravel. Reaction is slightly acid to mildly alkaline.
COMPETING SERIES: This is the Benridge Series. Benridge soils have an argillic horizon that has a component of amorphous material, is weakly or moderately smeary, and the clay content increases with increasing depth to 60 or more inches.
GEOGRAPHIC SETTING: The Kimball soils are on low terraces and have slopes of 0 to 15 percent. They formed in alluvium from a variety of sources including sedimentary, metasedimentary, metabasic and granitic rock. Elevations range from 30 to 1,000 feet. The climate is subhumid with hot, dry summers and cool, moist winters. The mean annual precipitation is 12 to 25 inches. Mean January temperature is 46 degrees to 50 degrees F.; mean July temperature is 75 degrees to 80 degrees F.; mean annual temperature is 59 degrees to 65 degrees F. Frost-free season ranges from 250 to 300 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Altamont, Arbuckle, Bruella, Corning, Hillgate, Perkins and San Joaquin soils. Altamont soils have clay textures throughout and are on hills above Kimball. Arbuckle soils have less than 35 percent clay and are on alluvial fans. Bruella and Perkins soils have less than 35 percent clay and are on stream terraces often dissecting areas of Kimball soils. Corning soils have moist values in the A horizon of more than 4 and are on relatively older, higher terraces. Hillgate soils have moist values in the A horizon of more than 4. San Joaquin soils have a duripan at 20 to 40 inches and are in similar landscape positions.
DRAINAGE AND PERMEABILITY: Well drained; low to medium runoff; slow saturated hydraulic conductivity.
USE AND VEGETATION: Used for irrigated crops, pasture, dryland small grain and rangeland. Natural vegetation is annual grasses and forbs and scattered blue oak.
DISTRIBUTION AND EXTENT: Sacramento and central coast valleys of California. Is used in Ventura, Yuba, Glenn, Tehama, Sacramento, Contra Costa, and Butte Counties. The soils are moderately extensive in MLRA-17.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Sacramento Valley Reconnaissance Survey, California, l9l3. (Type location established in Butte County prior to a modern soil survey being conducted).
REMARKS:
10/2006 minor edits, changed runoff terminology.
The Hopeton series is inactivated and combined with the Kimball series. Some of the soils mapped as Kimball series in the Ventura area soil survey are taxadjunct to the Kimball series because colors are redder and rock fragment content is higher than the range defined for Kimball series. Soils as mapped in Contra Costa Co. which have lime in the series control sections are also excluded in this revision. Difference in very fine sand content on a clay free basis between the BAt and Bt is 6 percent and is not considered enough to be a discontinuity. Soils mapped as Kimball with a duripan below a depth of 40 inches are now excluded from the concept.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from the surface to a depth of 10 inches (Ap1, Ap2, Ap3, A).
Argillic horizon - the zone from 17 to 46 inches (2Btss, 2Bt).
Pale great group - It has an abrupt upper boundary with an absolute clay increase of 15 to 30 percent more than the overlying horizon.
Mollic subgroup - organic matter is 1.2 to 3 percent in the upper part of the ochric epipedon.
CEC class was assumed.
ADDITIONAL DATA: Reference pedons RP84CA-115-26-2 for organic carbon and RP84CA-115-26-6 for mineralogy and base saturation by NSSL. Sampled by U.C. Davis l984 for particle size analysis on the 2Bt horizon. Type location sampled by University of California as 59CAL-04-2-1 to 8 in April, l959, for complete characterization. (Can not locate data)