From: Subject: Official Series Description - TEHAMA Series Date: Wed, 7 Jul 2010 13:30:52 -0700 MIME-Version: 1.0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Location: http://ortho.ftw.nrcs.usda.gov/osd/dat/T/TEHAMA.html X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5931 Official Series Description - TEHAMA Series

LOCATION TEHAMA             =
CA

Established Series
Rev:SBJ/GMK/WCL/DJE
01/2003

TEHAMA SERIES

The Tehama series consists of deep, well = drained soils=20 formed in mixed alluvium. Tehama soils are on fans and terraces and have = slopes=20 of 0 to 15 percent. The mean annual precipitation is about 25 inches and = the=20 mean annual air temperature is about 62 degrees F.

TAXONOMIC CLASS: Fine-silty, mixed, superactive, thermic Typic = Haploxeralfs

TYPICAL PEDON: Tehama silt loam - on a 2 percent south-facing = slope in=20 an idle field under annual grasses at 280 feet elevation. (Colors are = for dry=20 soil unless otherwise stated).

Ap--0 to 8 inches; pale brown (10YR 6/3) silt loam, brown = (10YR 5/3)=20 moist; massive; hard, friable, slightly sticky and slightly plastic; = many fine=20 roots; many very fine tubular pores; strongly acid (ph 5.5); abrupt = smooth=20 boundary.

A--8 to 19 inches; pale brown (10YR 6/3) silt loam, brown = (10YR 5/3)=20 moist, massive; hard, friable, slightly sticky and slightly plastic; = common very=20 fine roots in lower part; many very fine tubular pores; moderately acid = (pH=20 5.9); gradual smooth boundary. (Combined thickness of the A horizons 15 = to 22=20 inches).

At1--19 to 42 inches; light yellowish brown (2.5Y 6/3) silty = clay=20 loam, olive brown (2.5Y 4/3) moist; weak subangular blocky structure; = very hard,=20 firm, sticky and plastic; few fine roots; many very fine tubular pores; = many=20 thin clay films in pores and common thin clay films on peds; high bulk = density;=20 slightly acid (pH 6.5); gradual smooth boundary.

Bt2--42 to 50 inches; light yellowish brown (2.5Y 6/3) loam; = olive=20 brown (2.5Y 4/3) moist; massive; very hard, firm, sticky, plastic; few = roots;=20 many very fine tubular pores; many thin clay films in pores; neutral (pH = 7.1);=20 clear smooth boundary. (Combined thickness of the Bt horizons is 25 to = 35=20 inches).

2Bt--50 to 60 inches; light yellowish brown (2.5Y 6/3) very = gravelly=20 loam, olive brown (2.5Y 4/3) moist; massive; hard, very friable, = nonsticky and=20 nonplastic; common thin clay films in pores and on rock fragments.

TYPE LOCATION: Tehama County, California; about 1 mile = northwest of=20 Corning Southern Pacific Railroad depot, 1,200 feet west and 200 feet = south from=20 the NE corner of sec. 15, T. 24 N., R. 3 W., Corning Quadrangle 7.5 = minute=20 series.

RANGE IN CHARACTERISTICS: Thickness of the solum is over 60 = inches.=20 The mean annual soil temperature is 62 to 66 degrees F and exceeds 41 = degrees F=20 all year. The soil between the depths of 7 and 21 inches is dry in all = parts=20 from June to October and is moist in some part the rest of the year. The = particle-size control section averages 30 percent clay and has a range = of 11 to=20 15 percent fine sand or coarser, including fragments up to 7.5 cm in = diameter.

The A horizon is 10YR 6/2, 6/3, 6/4; 2.5Y 6/2, or 6/4 dry. Moist = colors are=20 10YR 5/3, 4/4, 4/3, 4/2; 2.5Y 4/2, or 4/4. Texture is silt loam, loam, = or fine=20 sandy loam. Reaction is strongly acid to slightly acid.

The Bt horizon is 10YR 6/3, 6/4, 5/2, 5/3; 2.5Y 6/3, 5/2, 5/4, 4/2, = or 4/4=20 dry. Moist colors are 10YR 4/3, 4/4; 2.5Y 4/2, 4/3 or 4/4. Texture is = silty clay=20 loam, clay loam or loam, and contains about 10 to 15 percent more clay = than the=20 A horizon. Reaction ranges from slightly acid to neutral.

The 2Bt horizon colors are 10YR 6/3, 6/4; 2.5Y 6/3, 6/4, or 6/6 dry. = Moist=20 colors are 10YR 4/2, 4/3; 2.5Y 4/2, 4/3, or 4/4. Textures are stratified = very=20 gravelly loam, very gravelly silt loam and very gravelly sandy loam. = Reaction=20 ranges from neutral to mildly alkaline. Some pedons have a perched water = table=20 at 36 to 50 inches from December through March.

COMPETING SERIES: These are the Kreyen= hagen=20 series in the same family and the Arbuckle<= /A>=20 series. Kreyenhagen soils have a paralithic contact within 60 inches; = (solum=20 thickness 60 inches or less) and have 50 to 75 percent slopes. Arbuckle = soils=20 have a fine-loamy control section.

GEOGRAPHIC SETTING: The Tehama soils are on terraces and fans = and have=20 slopes of 0 to 15 percent. The soils formed in mixed alluvium. = Elevations are 50=20 to 1,000 feet. The climate is Mediterranean with hot dry summers and = cool moist=20 winters. Mean annual precipitation varies from 15 to 35 inches. Mean = January=20 temperature is about 45 degrees F; mean July temperature is about 80 = degrees F;=20 mean annual air temperature is about 62 degrees F. Frost-free season = ranges from=20 250 to 280 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Corning, Redding, Red = Bluff and=20 Yolo = soils.=20 Corning soils are on slightly higher old terraces and have clay subsoil. = Redding=20 soils are on higher old terraces and have a duripan within 20 inches. = Red Bluff=20 soils have clayey, strongly acid subsoil. Yolo soils are on low recent = alluvial=20 fans and have clay loam subsoil with more than 15 percent fine sand or = coarser.

DRAINAGE AND PERMEABILITY: Well drained or moderately well = drained;=20 medium runoff; slow permeability.

USE AND VEGETATION: Small grains and pasture are grown where = this soil=20 is dry farmed. Row crops, pasture and a few orchards are grown under = irrigation.

DISTRIBUTION AND EXTENT: Sacramento Valley, California. Tehama = soils=20 are moderately extensive.

MLRA OFFICE RESPONSIBLE: Davis, California

SERIES ESTABLISHED: Tehama County, California, 1910.

REMARKS: Laboratory data by University of California, Davis = was used=20 to verify classification.

The activity class was added to the classification in January of = 2003.=20 Competing series were not checked at that time. - ET

Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - extends from 0 to 19 inches. Argillic horizon = extends from=20 19 to 50 inches. Control section which begins at 19 inches to 39 inches = has an=20 average of 30 percent clay and 12 percent fine sand or coarser including = fragments up to 7.5 cm in diameter by weight.

National Cooperative Soil Survey
U.S.A.