LOCATION VOLTA CAEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, thermic Typic Natraqualfs
TYPICAL PEDON: Volta clay loam - on a slope of 1 percent in flat rangeland at an elevation of 90 feet. (Colors are for dry soil unless otherwise stated. When described on May 12, 1976, the soil was moist below 4 inches but became saturated to near the surface when duripan was broken).
A--0 to 1 inch; light gray (2.5Y 7/2) clay loam, light olive brown (2.5Y 5/4) moist; moderate medium platy structure; slightly hard, friable, sticky and slightly plastic; common very fine, fine and medium roots; common very fine tubular pores; slightly effervescent with disseminated lime; strongly alkaline (pH 8.5); abrupt smooth boundary. (1 to 6 inches thick)
Btkn--1 to 4 inches; grayish brown (2.5Y 5/2) clay loam, light olive brown (2.5Y 5/4) moist; strong medium angular blocky structure; hard, firm, very sticky and plastic; few medium and common very fine and fine roots; many very fine tubular pores; many thin pressure faces; violently effervescent with disseminated lime; strongly alkaline (pH 8.5); abrupt wavy boundary. (2 to 8 inches thick)
Btn--4 to 11 inches; pale brown (10YR 6/3) clay loam, dark brown (10YR 3/3) moist; strong medium columnar structure; very hard, firm, sticky and very plastic; few medium and common very fine and fine roots; many very fine tubular pores; many moderately thick pressure faces; slightly effervescent with disseminated lime; EC is 3.0 mmhos/cm; ESP is 23; moderately alkaline (pH 8.0); clear smooth boundary. (5 to 10 inches thick)
BC--11 to 26 inches; very pale brown (10YR 7/4) clay loam, yellowish brown (10YR 5/6) moist; many medium prominent gray (5Y 6/1) mottles, many medium prominent greenish gray (5GY 5/1) mottles moist; strong medium prismatic structure; very hard, firm, sticky and very plastic; few fine and common very fine roots; many very fine tubular pores; many thin pressure faces; strongly effervescent with disseminated lime and segregated as common fine irregular soft masses; EC is 2.3 mmhos/cm; ESP is 11; moderately alkaline (pH 8.2); clear smooth boundary. (10 to 17 inches thick)
Bkg--26 to 46 inches; gray (5Y 5/1) and very pale brown (10YR 7/3) clay loam, very dark gray (5Y 3/1), olive (5Y 5/3) and light yellowish brown (10YR 6/4) moist; massive, hard, friable, sticky and plastic; few very fine roots; few fine tubular pores; strongly effervescent with disseminated lime and segregated as common fine irregular soft masses; moderately alkaline (pH 8.2); abrupt smooth boundary. (15 to 22 inches thick)
2C--46 to 60 inches; light gray (10YR 7/2), pale brown (10YR 6/3), and gray (5Y 6/1) duripan (20 percent durinodes), brown coarse, dark brown (10YR 5/3, 3/3) moist, many medium prominent greenish gray (5GY 5/1) moist mottles.
TYPE LOCATION: Merced County, California; 1.3 miles south of the community of Ingomar and 10 miles NW of Los Banos, 300 feet NE of the Ingomar Road and Husman Road intersection, 300 feet NE of the SW corner of SE 1/4 of sec. 10, or 2,300 feet west and 300 feet north of the SE corner of sec. 10, T. 9 S., R. 9 E.
RANGE IN CHARACTERISTICS: Most years the profile is saturated to within 12 inches of the surface, from December through March, from a perched water table. The mean annual soil temperature is 59 degrees to 64 degrees F. The depth to duripan ranges from 45 to 55 inches. The Bkg horizon has 30 to 45 percent clay content. The ESP of the Bt horizon ranges from 15 to 30.
The A horizon dry color is 10YR 4/2, 5/1, 6/2; 2.5Y 4/4, 5/2, 6/2 or 7/2. Moist colors are 10YR 3/2, 4/2, 5/2, 5/4; 2.5Y 3/2, 4/3, 5/2, 5/4 or 5Y 4/3. Some pedons may have mottles when moist. Clay content is 27 to 40 percent. The structure is weak medium subangular blocky in Ap horizons. The EC is less than 2 mmhos/cm and the ESP is less than 15. Soil in some pedons does not effervesce. It ranges from mildly alkaline to strongly alkaline. Some pedons do not have an A horizon where fields are leveled. Some pedons have an E horizon.
The Bt horizon dry color is 10YR 6/3, 7/4; 2.5Y 5/2 or 6/2. In some horizons mottles range from few fine distinct to common medium prominent and are 10YR 6/3, 7/4; 2.5Y 7/4; or 5Y 6/1. Moist colors are 10YR 3/2, 3/3, 4/4, 5/4, 5/6, 6/3; 2.5Y 3/2, 4/2, 5/4; 5Y 4/1, 4/2, 5/1 or 5/3. Moist mottles range from few fine distinct to many medium prominent and are 10YR 4/2, 4/3; 2.5Y 4/2, 7/4; 5Y 3/1, 4/1, 6/1; or 5GY 5/1. Most pedons, when moist, have mottles with chromas of 2 or less in addition to other chromas. It is clay loam or clay with 35 to 50 percent clay content and always has more than 1.2 times more clay than the A horizon. Some pedons have clay films. The EC ranges from 2 to 6 mmhos/cm. ESP is 15 to 30. It is slightly to violently effervescent. It is moderately alkaline or strongly alkaline.
The Bkg horizon dry color is 10YR 7/3; 2.5Y 4/2, 5/4; 5Y 5/1 or 7/3. In some pedons mottles are few fine distinct 10YR 4/6, 8/6; or 5Y 7/1. Moist colors are 10YR 4/3, 5/4, 6/4; 2.5Y 4/2, 4/4, 5/3, 6/4; 5Y 3/1, 5/2, 5/3, 6/1 or 5GY 5/1. Moist mottles are common medium prominent 7.5YR 3/2; 2.5Y 5/4, 6/4; or 5Y 6/1. It is clay loam or clay with 30 to 45 percent clay content. The EC ranges from 2 to 6 mmhos/cm. The ESP ranges from 8 to 15. It is slightly to violently effervescent and is moderately alkaline or strongly alkaline.
The 2C horizon dry color si 10YR 5/4, 6/3, 7/2, 8/3; 2.5Y 6/4; 5Y 4/1, 6/1 or 8/1. Mottles range from few fine distinct to common medium prominent and are 5Y 6/1 or 6/2. Moist colors are 10YR 3/3, 5/3, 5/4, 6/4; 2.5Y 5/4; 5Y 5/3, 8/2; or 5B 4/1. Moist mottles range from few fine prominent to many medium prominent and are 5Y 4/2 or 5GY 5/1. Some parts of the pan are stratified and lenses or strata of sandy clay loam, clay loam or clay. Durinoides range from 20 to 80 percent, are from 2 to 30 mm in size, and may be rounded or angular. Some pedons have an opal laminar cap on top of the pan. The pan is thicker than 30 inches, is stratified with soil material, and extends to depths below 90 inches. The artesian water flows through and under the pan.
COMPETING SERIES: This is the Healdton series in the same family and the Britto, Devries (T), Dosamigos, Pedcat, Rioblanco, Santanela, and Turlock series in other families. Rioblanco and Devries soils have a dark colored A horizon and lack a natric horizon. Britto soils lack a duripan. Dosamigos soils lack a duripan and a natric horizon. Healdton soils lack a duripan, occur on flood plains that are occasionally flooded, and occur in a moist subhumid climate. Pedcat soils have a xeric moisture regime bordering on aquic and lack a duripan. Santanela and Turlock soils are fine-loamy and lack a duripan.
GEOGRAPHIC SETTING: Volta soils are on low alluvial fans and the valley basin rim. These soils are formed in mixed alluvium dominantly from sedimentary rock sources. They are on nearly level topography. elevations are 80 to 110 feet. The climate is semiarid with hot dry summers and cool moist winters. The mean annual precipitation is about 9 to 12 inches. The mean January temperature is 46 degrees F; mean July tmeperature is 79 degrees F; and mean annual temperature is about 62 degrees F. Frost-free season is 210 to 280 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Britto, Dosamigos, and Pedcat soils and the Marcuse and Triangle soils. Marcuse soils lack a duripan and a natric horizon. Triangle soils have wide cracks upon drying and lack a duripan or natric horizon.
DRAINAGE AND PERMEABILITY: Poorly drained (some areas have been artifically drained). There is artesian water pressure under the duripan which forces water to near or at the surface when the pan is ruptured. Very slow runoff, very slow permeability.
USE AND VEGETATION: These soils are used for irrigated pasture and as rangeland. Where drained they are used for sugar beet, alfalfa, corn, rice, and barley production.
DISTRIBUTION AND EXTENT: These soils occur on low alluvial fans and the basin rim of the Central San Joaquin Valley adjacent to the Coast Range foothills. They are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Merced County, California 1940.
REMARKS: This soil is being reactivated. It was originally classified as a maximal solonetz soil. These were mapped as Volta soils in the Los Banos Area soil survey. They are being redefined to include a thicker duripan and hydrostatic water table pressure under and in the duripan. The control section in differentiation of series (page 391, item (3); Soil Taxonomy) is to the bottom of named diagnostic horizons and any subjacent Cca horizon if the thickness of both exceeds 1 meter. EC and ESP determined by saturation extract, solubridge and versenate titration method. pH determined by colorimetric method using Thymol Blue and Hellige-Troug Triplex indicators. Texture determined by modified Bouyoucos method. Calcium carbonate equivalent determined by field HC1 double syringe kit. Organic matter determined by Walkley-Black digestion method.
The activity class was added to the classification in March of 2003. Competing series were not checked at that time. - ET