LOCATION ALCAPAY CAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Sodic Haploxererts
TYPICAL PEDON: Alcapay clay - fallow. (Colors are for dry soil unless otherwise noted.) When described on April 25, 1988, the soil was dry to 5 inches and moist below.
Ap1--0 to 5 inches; olive gray (5Y 4/2) clay, dark brown (10YR 3/3) moist, massive; hard, friable, sticky and plastic; many very fine roots; few fine interstitial pores; many fine prominent yellowish red (5YR 4/6) moist masses of iron accumulations; slightly acid (pH 6.1); abrupt wavy boundary.
Ap2--5 to 10 inches; brown (10YR 5/3) clay, brown (10YR 4/3) moist, strong coarse prismatic structure; very hard, friable, sticky and plastic; many very fine roots; few very fine interstitial pores; common fine distinct yellowish brown (10YR 5/6) and pale brown (10YR 6/3) masses of iron accumulation; moderately alkaline (pH 8.0); clear wavy boundary.
Bw--10 to 24 inches; yellowish brown (10YR 5/4) clay, dark yellowish brown (10YR 4/4) moist, strong coarse prismatic structure; very hard, firm, sticky and plastic; few very fine roots; few very fine tubular pores; white crystals in seams and accumulations; many fine distinct very pale brown (10YR 7/4) moist masses of iron accumulation; moderately alkaline (pH 8.2); clear wavy boundary.
Bssz--24 to 35 inches; yellowish brown (10YR 5/4) clay, dark yellowish brown (10YR 4/4) moist, weak moderate subangular blocky structure; very hard, firm, sticky and plastic; few very fine roots; common very fine tubular pores; white crystals in seams and accumulations; slickensides tilted 60 degrees from vertical; effervescent with common fine lime accumulations in filaments; few fine faint dark brown (10YR 3/3) moist masses of iron accumulation; slightly alkaline (pH 7.8); clear smooth boundary.
Bnz1--35 to 53 inches; yellowish brown (10YR 5/4) clay, dark yellowish brown (10YR 4/4) moist; weak moderate subangular blocky structure; very hard, firm, sticky and plastic; few very fine roots; many very fine tubular pores; white crystals in seams and accumulations; effervescent with few fine lime accumulations in filaments; moderately alkaline (pH 8.3); clear smooth boundary.
Bnz2--53 to 64 inches; yellowish brown (10YR 5/6) clay, brown (7.5YR 4/4) moist, massive; very hard, friable, sticky and plastic; few very fine tubular pores; white crystals in seams and accumulations; strongly effervescent with many fine rounded lime accumulations in small masses; many manganese accumulations in fine rounded small masses; many fine distinct dark brown (10YR 3/3) moist masses of iron accumulation; very strongly alkaline (pH 8.8).
TYPE LOCATION: Colusa County, California; located about 7 miles northwest of Maxwell CA; 4400 feet south and 5700 feet east of the NW corner of sec. 32, T.18N., R.3W. MDB&M, 39 degrees, 22 minutes 24 seconds North latitude, 122 degrees, 13 minutes, 39 seconds West longitude.; USGS Maxwell CA Quadrangle.
RANGE IN CHARACTERISTICS:
Depth to Bnz horizon - ranges from 10 to 40 inches.
Slickensides and pressure faces - common below plow zone from depths of about 10 to about 40 inches. These soils have cracks 30 to 50 inches deep unless irrigated that open in May and June and remain open until November.
Soil Temperature - mean annual soil temperature ranges from 62 to 64 degrees F.
Ap horizon - Hue: 10YR
Value: 4,5 dry, 3,4 moist
Chroma: 2,3 dry, 2,3 moist
Additional Hue: 5Y
Value: 4 dry, 3 moist
Chroma: 2 dry, 2 moist
Texture: clay
Reaction: slightly acid to moderately alkaline
Bw and Bssz horizons - Hue: 10YR
Value: 5 dry, 3,4 moist
Chroma: 4 dry, 3,4 moist
Texture: clay
Reaction: neutral to moderately alkaline
Carbonates - segregated lime in the lower part
Bnz horizon - Hue: 10YR
Value: 5 dry, 4 moist
Chroma: 4,6 dry, 3,4 moist
Additional hue: 7.5YR
Value: 4 moist
Chroma: 4 moist
Texture: clay
Reaction: moderately to very strongly alkaline
Carbonates - lime occurs in soft seams
Sodium Adsorption Ratio - greater than 13 to as high as 50
COMPETING SERIES: These are no other soils in this family.
GEOGRAPHIC SETTING: Alcapay soils are in nearly level basins at elevations of 45 to 115 feet. The soils formed in alluvium from mixed rock sources. The climate is dry subhumid, mesothermal, with hot, dry summers and cool moist winters. Average annual precipitation is 14 to 16 inches. Average January temperature is 45 degrees F., average July temperature is 78 degrees F., and mean annual temperature is about 60 to 62 degrees F. The average frost-free season is 225 to 250 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are Capay, Willows and Hillgate soils. Capay soils do not have an SAR above 13 in the upper 40 inches. Hillgate soils have fine textured argillic horizons and lack SAR above 13. Willows soils are poorly and very poorly drained.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; negligable to low runoff; slow permeability. Water table is at 4 to 6 feet from December to April and have been artificially drained.
USE AND VEGETATION: The soils are used for rice. Native vegetation is annual grasses and forbs.
DISTRIBUTION AND EXTENT: This soil occurs on the west side of the Sacramento Valley. The soils are not extensive. MLRA 17.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Colusa County, California, 1994.
REMARKS:
Diagnostic Horizons and features recognized in this pedon are:
1. Ochric Epipedon - 0 to 10 inches (Ap1, Ap2)
1.1 Moist values are 4 except in upper 5 inches.
2. Sodic Subgroup - SAR greater than 13 at 35 inches, see data below.
Other Diagnostic Horizons or Soil Characteristics:
1. Chemical data:
HORIZON DEPTH pH1:1 pH1:10 ECe Ca+Mg TOT. SOL.SALTS
Ap1 0-8 6.1 7.1 0.6 - 6.7
Ap2 8-24 8.0 8.0 0.8 3 8.9
Bw 24-36 8.2 8.4 1.0 2 11.1
Bssz 36-46 7.8 7.8 6.6 33 73
Bnz1 46-60 8.3 8.9 4.5 5 50
Bnz2 60-70 8.8 9.5 4.9 3 54
HORIZON DEPTH SAR CaO3
Ap1 0-8 - -
Ap2 8-24 4.8 -
Bw 24-36 9.1 -
Bssz 36-46 9.9 7.0
Bnz1 46-60 28.5 -
Bnz2 60-70 41.8 8.5
2. Temperature - Moisture (Xeric-Thermic)
2.1 The 7 to 21 inch SMCS is dry in all parts from May 15 to
October 31 and is moist in some or all parts from November 1
to May 15.
2.2 The MAST is 62 to 64 degrees F.
ADDITIONAL DATA: Lab analyses were run in the project office lab on samples from the type location.