LOCATION GAZWELL CAEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, thermic Cumulic Endoaquolls
TYPICAL PEDON: Gazwell mucky clay--on a slope of less than 1 percent in a cultivated field at an elevation of 15 feet below sea level. (Colors are for dry soil unless otherwise stated. When described the soil was moist below 3 inches).
Ap1--0 to 8 inches; dark grayish brown (10YR 4/2) mucky clay, very dark grayish brown (10YR 3/2) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; many very fine roots; many fine interstitial pores; 15 percent organic matter; moderately acid (pH 6.0); clear smooth boundary. (2 to 20 inches thick)
Ap2--8 to 17 inches; dark grayish brown (10YR 4/2) mucky clay, very dark brown (10YR 2/2) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; many very fine roots; many very fine interstitial pores; 14 percent organic matter; moderately acid (pH 6.0); gradual smooth boundary. (9 to 17 inches thick)
Ap3--17 to 30 inches; dark grayish brown (10YR 4/2) mucky clay, very dark brown (10YR 2/2) moist; massive, slightly hard, very friable, slightly sticky and slightly plastic; many very fine roots; many very fine interstitial pores; common, fine reddish brown (5YR 4/4) moist fragments of burnt material mixed throughout; 13 percent organic matter; moderately acid (pH 6.0); abrupt wavy boundary. (7 to 13 inches thick)
2Ab--30 to 36 inches; very dark gray (10YR 3/1) mucky clay, black (10YR 2/1) moist; few medium distinct yellowish red (5YR 4/6) mottles, dark reddish brown (5YR 3/4) moist; massive; slightly hard, very friable, nonsticky and nonplastic; common very fine roots; many very fine interstitial pores; discontinuous dark yellowish brown (10YR 4/4) moist 0.5 inch thick bands of burnt material; 25 percent organic matter; moderately acid (pH 5.8); abrupt smooth boundary. (4 to 7 inches thick)
3Oa1--36 to 48 inches; very dark gray (10YR 3/1) broken face sapric material, black (10YR 2/1) moist; common fine distinct strong brown (7.5YR 4/6) mottles, red (2.5YR 4/8) moist; no visible fibers; massive; slightly hard, very friable, nonsticky and nonplastic; 65 percent mineral material; very strongly acid (pH 5.0 in water); abrupt wavy boundary. (5 to 16 inches thick)
3Oa2--48 to 61 inches; very dark gray (10YR 3/1) broken face sapric material, black (10YR 2/1) moist; about 40 percent fibers, less than 5 percent rubbed; strong very fine platy structure; slightly hard, firm, nonsticky and nonplastic; dark brown (10YR 3/3) fibers, dark yellowish brown (10YR 3/4) moist; 67 percent mineral material; moderately acid (pH 6.0 in water). (10 to 15 inches thick)
TYPE LOCATION: Sacramento County, California; about 2.3 miles southeast of Rio Vista on Brannan Island, 2,150 feet northeast from Tomato Slough on dirt road on north side of major drain and 200 feet north into field in an unsectionized area; W. Longitude 121 degrees 39' 40" N. Latitude 38 degrees 07' 50".
RANGE IN CHARACTERISTICS: The mean annual soil temperature at a depth of 20 inches ranges from 62 degrees F to 65 degress F and remains above 47 degrees F throughout the year. It is assumed that the soil between the depths of 5 and 15 inches was saturated before it was artificially drained. Depth to the buried organic soil ranges from 28 to 39 inches. The textural control section from a depth of 10 inches to the upper boundary of the organic soil has a weighted average clay content of 40 to 60 percent and a weighted average organic matter content of 10 to 20 percent. Stratification is weak in this soil and is expressed as a variation in organic matter content.
The Ap horizon has dry color of 10YR 5/1, 4/2, 4/1 or 3/1 and moist color of 10YR 3/2, 3/1, 2/2 or 2/1. It is mucky clay or mucky silty clay with 40 to 60 percent clay and 7 to 15 percent organic matter. Reaction is strongly acid to slightly acid.
The Ab horizon has dry color of 10YR 5/1, 4/1, or 3/1 and moist color of 10YR 3/1 or 2/1. It is mucky clay or mucky silty clay with 40 to 60 percent clay and 10 to 27 percent organic matter. Reaction is strongly acid to slightly acid. Some pedons have a burned layer that is 0.5 to 2 inches in thickness within the Ab or Oa1 horizons at a depth of 20 to 45 inches. Moist color is 10YR 5/6, 4/4; 7.5YR 4/6, 4/3; 5YR 5/6, 5/4 or 2.5YR 4/8.
The Oa horizon has dry color of 10YR 5/1, 4/1, 3/1 or N 2/0 and moist color of 10YR 2/1 or N 2/0. Fiber content ranges from less than 5 percent in the upper part to about 70 percent in the lower part. Most fibers are destroyed by rubbing when moist. Organic matter content is 27 to 40 percent. Reaction is very strongly to moderately acid.
COMPETING SERIES: There are no other soils in this family. Similar soils in other families are the Peltier (T), Rindge and Ryde series. Peltier soils do not have a buried Histosol. Rindge soils are organic soils. Ryde soils have a fine-loamy textural control section and do not have a buried Histosol.
GEOGRAPHIC SETTING: Gazwell soils are in backswamps along the edge of fresh water marshes. Slopes are 0 to 2 percent. They formed in alluvium derived from mixed rock sources underlain by decomposed hydrophytic plant remains. The plant remains consist of reeds and tules. Elevations are 15 feet below sea level to sea level. The climate is dry subhumid with hot dry summers and cool moist winters. Mean annual precipitation is 13 to 17 inches. Average January temperature is 46 degrees F, average July temperature is 75 degrees F and the average annual temperature is 61 degrees F. Frost-free season is 275 to 300 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Rindge and the Sailboat, and Scribner soils. Sailboat and Scribner soils have a fine-loamy textural control section. Sailboat soils are on natural levees. Scribner soils are on edges of backswamps.
DRAINAGE AND PERMEABILITY: Natural drainage is very poor. These soils are artificially drained, runoff is very slow, permeability is moderate in the mineral soil and rapid in the underlying organic soil. The water table is maintained by pumping at a depth of 18 to 60 inches. Depth to water table is 18 to 36 inches in winter and early spring months. These soils subside. These soils are protected by levees and have a rare hazard of flooding.
USE AND VEGETATION: Soils are cultivated. Corn and wheat are the principle crops.
DISTRIBUTION AND EXTENT: Sacramento-San Joaquin Delta area. The soils are moderately extensive.
MLRA OFFICE RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Sacramento County, 1985. Name is coined.
REMARKS: The activity class was added to the classification in February of 2003. Competing series were not checked at that time. - ET
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: 0 to 36 inches (Ap1, Ap2, Ap3, 2Ab horizons)
Buried Histosol: 36 to 60 inches (3Oa1, 3Oa2 horizons)
Aquoll feature; artificially drained; has distinct mottles in lower part of mollic epipedon.
Organic matter by induction furnace (UCD), clay content by hydrometer after organic matter oxidized with hydrogen peroxide.