LOCATION DIYOU CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Fluvaquentic Haploxerolls
TYPICAL PEDON: Diyou loam--on a 1 percent slope at 2,868 feet elevation--irrigated pasture. (Colors are for dry soil unless otherwise noted. When described on July 7, 1964, the soil was moist to a water table at 30 inches.)
A--0 to 11 inches; dark grayish brown (2.5Y 4/2) loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many very fine roots; common fine and very fine tubular pores; slightly alkaline (pH 7.5); clear smooth boundary. (10 to 12 inches thick)
C--11 to 15 inches; grayish brown (2.5Y 5/2) sandy loam, dark grayish brown (2.5Y 4/2) moist; massive; soft, very friable, nonsticky and nonplastic; clear smooth boundary. (4 to 10 inches thick)
Agb--15 to 36 inches; gray (5Y 5/1) sandy clay loam, dark gray (5Y 4/1) moist; massive; very hard, firm, slightly sticky and slightly plastic; common fine roots; common fine and very fine tubular pores; saturated with free water at 30 inches; common fine prominent brownish yellow (10YR 6/6) and dark yellowish brown (10YR 5/6) moist, masses of iron accumulation; slightly alkaline; clear smooth boundary. (10 to 19 inches thick)
Cg1--36 to 47 inches; light olive gray (5Y 6/2) clay loam, dark olive gray (5Y 3/2) moist; massive; very hard, firm, moderately sticky and moderately plastic; saturated with free water; common prominent brownish yellow (10YR 6/6) and yellowish brown (10YR 5/6) moist, masses of iron accumulation; slightly alkaline (pH 7.5); clear smooth boundary. (10 to 15 inches thick)
Cg2--47 to 60 inches; light olive gray (5Y 6/2) sandy loam, dark olive gray (5Y 3/2) moist; massive, hard, very friable, nonsticky and nonplastic; saturated with free water; slightly alkaline (pH 7.5).
TYPE LOCATION: Siskiyou County, California; in the Scott Valley Area about 4 miles southeast of Etna; about 1,830 feet east and 250 feet north of the southwest corner of section 13, T. 41 N., R. 9 W.
RANGE IN CHARACTERISTICS:
Soil moisture - Usually moist in the moisture control section in winter and spring, dry in summer and fall unless irrigated; the upper part of the moisture control section is dry for 120 to 150 days; xeric moisture regime that borders on aridic.
Soil temperature - Mean annual temperature is 51 to 54 degrees F.; mean January soil temperature is 35 to 39 F.; mean July soil temperature is 70 to 74 degrees F.
Mollic epipedon thickness - 10 to 12 inches.
Stratification - The soil commonly is stratified and has buried A horizons.
Depth to buried horizons - 14 to more than 40 inches.
Control section - Clay content: averages 18 to 25 percent; Rock fragments: 0 to 15 percent, mainly pebbles.
Reaction - Neutral or slightly alkaline.
Salinity (EC) - 0 to 2 mmhos/cm.
A or Ap horizon - Hue: 10YR or 2.5Y.
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 1 or 2, dry or moist.
Organic matter content: 2 to 5 percent.
C horizon - Value: 5 or 6 dry.
Texture: Stratified sandy loam to clay loam.
Agb horizon - Chroma: 1 or 2, dry or moist.
Texture: Stratified sandy loam to clay loam.
Redoximorphic features: Redox concentrations occur as masses of iron accumulation with moist color of 10YR 6/6, 5/3, 5/4, or 5/6. Redox depletion of iron has occurred in the matrix and is indicated by strong gleying.
Cg horizons - Chroma: 1 or 2, dry or moist.
Texture: Stratified sandy loam to clay loam.
Redoximorphic features: Redox concentrations occur as masses of iron accumulation with moist color of 10YR 6/6, 5/3, 5/4, or 5/6. Redox depletion of iron has occurred in the matrix and is indicated by strong gleying.
Other features: Some pedons are underlain by peat between 40 and 60 inches.
COMPETING SERIES: These are the Mindlebaugh (T) and Truckee series. Mindlebaugh soils have an aridic moisture regime that borders on xeric and have horizons with identifiable secondary carbonates. Truckee soils have an aridic moisture regime that borders on xeric and are effervescent throughout.
GEOGRAPHIC SETTING: Diyou soils are on flood plains. These soils formed in alluvium derived from mixed sources. Slopes are 0 to 2 percent. Elevations range from 2,000 to 4,000 feet. The climate is subhumid with cold, moist winters and warm, dry summers. The mean annual precipitation is 15 to 25 inches. The seasonal snowfall is 24 to 36 inches. The mean annual temperature is 48 to 52 degrees F., mean January temperature is 34 to 38 degrees F., and the mean July temperature is 68 to 71 degrees F. The frost-free period is 95 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dotta, Settlemeyer, and Stoner soils. Dotta and Stoner soils are well drained and are on alluvial fans at slightly higher elevations. Also, Dotta soils are fine-loamy and have argillic horizons and Stoner soils are coarse-loamy and have ochric epipedons. Settlemeyer soils are poorly drained and have an aquic moisture regime.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; medium surface runoff; moderately slow permeability. Endosaturation is present with an apparent seasonal high water table between 2 and 3 feet (moderately deep free water occurrence class) from February through June. Cumulative annual duration class is Common. The water table fluctuates between 3 and 5 feet from July through January. Drained phases exist with endosaturation between 3 and 5 feet from February through June. These soils are susceptible to occasional flooding for brief periods between December and May or rare flooding for brief periods year-round.
USE AND VEGETATION: Diyou soils are used mainly for cropland, and much of the acreage is irrigated. Small grains, alfalfa, and pasture are the principal crops. The native vegetation is carex, rush, tufted hairgrass, bluegrass, and water-tolerant grasses and forbs.
DISTRIBUTION AND EXTENT: High mountain valleys of northern California. These soils are moderately extensive. MLRA 21.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Siskiyou County, California, 1978.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 11 inches (A horizon).
Aquic conditions - The conditions of endosaturation and reduction accompanied by redox depletions in the zone from 15 to 60 inches (Agb, Cg1, and Cg2 horizons).
Particle size control section - The zone from 10 to 40 inches (Agb horizon and parts of the A, C, and Cg1 horizons).