LOCATION ROHNERVILLE CA
Established Series
Rev. JCM/RCH/JWH/
05/2016
ROHNERVILLE SERIES
The Rohnerville series consists of very deep, well drained soils on uplifted terraces and fan remnants. These soils formed in mixed alluvium. Slopes range from 0 to 15 percent. Mean annual precipitation is about 1250 millimeters. Mean annual temperature is about 11 degrees C.
TAXONOMIC CLASS: Fine, mixed, active, mesic Xeric Haplohumults
TYPICAL PEDON: Rohnerville silt loam on a 0 percent slope under permanent pasture. (Colors are for dry conditions unless otherwise noted).
Ap--0 to 20 centimeters; grayish brown (10YR 5/2) silt loam, dark brown (7.5YR 3/2) moist; 23 percent clay; strong medium granular structure; moderately hard, friable, moderately sticky and moderately plastic; common very fine roots throughout; common very fine tubular pores; noneffervescent; neutral (pH 6.6); clear smooth boundary.
ABt--20 to 58 centimeters; grayish brown (10YR 5/2) silty clay loam, dark brown (7.5YR 3/2) , moist; 30 percent clay; moderate fine subangular blocky structure parting to strong medium granular structure; friable, moderately hard, moderately sticky and moderately plastic; common very fine roots throughout; common very fine tubular pores; noneffervescent; neutral (pH 6.6); abrupt smooth boundary. (Combined thickness of the A horizons is 50 to 75 centimeters)
Bt1--58 to 76 centimeters; light yellowish brown (10YR 6/4) silty clay loam, brown (7.5YR 4/3) moist; 35 percent clay; weak medium subangular blocky structure; friable, very hard, moderately sticky and very plastic; few very fine roots throughout; common medium tubular pores; 30 percent distinct clay films on all faces of peds; noneffervescent; moderately acid (pH 5.6); clear wavy boundary.
Bt2--76 to 120 centimeters; light yellowish brown (10YR 6/4) silty clay, brown (7.5YR 5/4) moist; 41 percent clay; weak medium subangular blocky structure; firm, extremely hard, moderately sticky and very plastic; 50 percent distinct clay films on all faces of peds; noneffervescent; moderately acid (pH 5.6); clear smooth boundary.
Bt3--120 to 140 centimeters; light yellowish brown (10YR 6/4) silty clay, brown (7.5YR 5/4) moist; 36 percent clay; weak medium subangular blocky structure; firm, extremely hard, moderately sticky and very plastic; 50 percent distinct clay films on all faces of peds; noneffervescent; moderately acid (pH 5.6); clear smooth boundary. (Combined thickness of the Bt horizons is 50 to 100 centimeters)
BCt--140 to 170 centimeters; very pale brown (10YR 7/4) silty clay loam, yellowish brown (10YR 5/4) moist; 29 percent clay; weak coarse subangular blocky structure; friable, very hard, moderately sticky and very plastic; 20 percent distinct clay films on all faces of peds; noneffervescent; neutral (pH 6.6); clear smooth boundary. (Thickness of a BC or C horizon is 50 to 75 centimeters)
TYPE LOCATION: Humboldt County, California. Hydesville area 1/2 mile south of Highway 36 near old Hydesville School; USGA 7.5 minute Quadrangle Hydesville, CA; WGS84 Decimal degrees 40.5448000, -124.0942700 longitude; UTM Zone 10 407338mE, 4488803mN; NAD83.
RANGE IN CHARACTERISTICS:
Soil moisture: The soil moisture control section is dry in all parts for 45 or more consecutive days after the summer solstice and moist in all parts from November through May. The soils have a xeric soil moisture regime
Soil Temperature: The soils have a mean summer and mean winter soil temperature that differs by more than 6 degrees C. and a mean soil temperature between 12 degrees C. and 14 degrees C.
Thickness of the umbric epipedon: 50 to 100 centimeters thick
Base Saturation: Base saturation is less than 50 percent by ammonium acetate in the epipedon. Base saturation is less than 35 percent by sum of cations in all B horizons.
Particle size control section (weighted average):
Rock fragments: 0 to 10 percent gravel
Clay content: 35 to 45 percent
A horizon:
Hue: 10YR or 7.5YR
Value: 4 or 5, 2 or 3 moist
Chroma: 1 to 3, moist or dry
Texture: Loam, silt loam, or silty clay loam.
Clay content: 20 to 30 percent
Rock fragments: 0 to 10 percent gravel
Reaction: slightly to strongly acid
B horizon:
Hue: 10YR or 7.5YR
Value: 5 or 6, 4 or 5 moist
Chroma: 3 or 4, moist or dry
Texture: silty clay, sandy clay, or silty clay loam.
Clay content: 35 to 45 percent
Rock fragments: 0 to 10 percent gravel
Reaction: moderately or strongly acid
C horizon: (when present)
Hue: 10YR
Value: 6 or 7, 5 or 6 moist
Chroma: 4 to 6, moist or dry
Texture: silty clay loam, clay loam, or sandy clay loam
Clay content: 25 to 35 percent
Reaction: moderately or strongly acid
COMPETING SERIES: These are the
Bellpine,
Gelderman,
Nekia, and
Windygap soil series. Bellpine soils are 50 to 100 centimeters to a paralithic contact from sedimentary origin. Gelderman soils are 50 to 100 centimeters to a paralithic contact derived from basalt and tuffaceous materials. Nekia soils are 50 to 100 centimeters deep to a lithic contact from igneous origin. Windygap soils are 100 to 150 centimeters deep to a paralithic contact from sedimentary origin.
GEOGRAPHIC SETTING: Rohnerville soils occur on uplifted marine and river terraces with slopes of 0 to 15 percent. The soils are formed on alluvium from sedimentary rocks, dominantly sandstone and mudstone. Elevations are 30 to 305 meters. The climate is subhumid with warm, dry summers influenced by a cooling marine layer, and cool, wet winters. Mean annual precipitation is from 900 to 1270 millimeters. Mean annual temperature is 13 to 14 degrees C. Frost-free season is 280 to 300 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the
Hookton,
Noyo, Bodega,
Millstreet, and
Kneeland. Noyo soils have ochric epipedons and very strongly acid argillic horizons. Bodega soils have mollic epipedons and are slightly acid throughout. Millstreet soils have redoximorphic features above 100 centimeters. Kneeland soils have hard bedrock above 100 centimeters.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained with moderately low saturated hydraulic conductivity and medium to high runoff.
USE AND VEGETATION: Used for dryland range, permanent pasture and some row crops. Vegetation consists of annual grasses and legumes, especially rye and subterranean clover. Sweet Vernal grass and poverty oat grass are abundant perennials.
DISTRIBUTION AND EXTENT: Coastal Redwood Belt, MLRA 4B. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Eureka Area, California, 1925. Name from the town of
Rohnerville, Humboldt County, California.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
1. Umbric epipedon: the zone from 0 to 58 centimeters. (Ap, ABt)
2. Argillic horizon: the zone from 20 to 140 centimeters. (Bt1, Bt2, Bt)
ADDITIONAL DATA: The soils were formerly classified in the Brunizem group and were well to moderately well drained.
NASIS User Pedon ID. 13CA600400
NSSL Pedon ID. UCD6212014
OSED scanned by SSQA. Last revised by state on 6/66.
Series reclassified 5/95. Competing series not updated at that time.
The activity class was added to the classification in February of 2003. Competing series were not checked at that time. ET
The type location was changed in 2014 to update the profile, limit the landscape position, and to provide a pedon for Characterization by KSSC.
Soil was sampled in 1962 by University of California At Davis. Data was entered into the NSSC database (62-CA-12-014). Lab data shows evidence of weak argillic horizon and control section in fine family.
Soil textures and coarse fragment content were modified from previous OSD based on current observations and NASIS data. Permissible landforms and drainage classes have been reduced to better define characteristics of the Rohnerville series.
Keys to Soil Taxonomy, 12th edition.
National Cooperative Soil Survey
U.S.A.