LOCATION AVA IL+IN OHEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, active, mesic Oxyaquic Fragiudalfs
TYPICAL PEDON: Ava silt loam - on a 3 percent convex slope in a pasture of grass-legume mixture at an elevation of about 440 feet above MSL. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 6 inches; dark grayish brown (10YR 4/2) silt loam, light brownish gray (10YR 6/2) dry; moderate fine granular structure; friable; many fine roots; slightly acid; abrupt smooth boundary. (5 to 10 inches thick)
E--6 to 10 inches; brown (10YR 4/3) silt loam; weak medium platy structure; friable; few fine roots; strongly acid; clear smooth boundary. (0 to 8 inches thick)
BE--10 to 14 inches; yellowish brown (10YR 5/6) silt loam; moderate fine and medium subangular blocky structure; friable; common fine roots; strongly acid; clear smooth boundary. (0 to 6 inches thick)
Bt--14 to 24 inches; yellowish brown (10YR 5/4) silty clay loam; strong fine and medium subangular blocky structure; firm; few fine roots; very few distinct brown (7.5YR 5/4) clay films and light yellowish brown (10YR 6/4) clay depletions on faces of peds; very strongly acid; clear smooth boundary. (8 to 14 inches thick)
Bt/E--24 to 27 inches; yellowish brown (10YR 5/4) silty clay loam (Bt), and light yellowish brown (10YR 6/4) silt (E), light gray (10YR 7/2) dry; the E material occurs as common distinct clay depletions on faces of peds and as fillings in spaces between peds; moderate fine and medium subangular blocky structure; firm; few fine roots; common medium distinct brown (7.5YR 4/4) masses of iron accumulation in the matrix; very few fine black (10YR 2/1) concretions (iron and manganese oxides); very strongly acid; clear smooth boundary (0 to 6 inches thick)
B't--27 to 34 inches; dark yellowish brown (10YR 4/4) silty clay loam; moderate medium subangular blocky structure; firm; few fine roots; common distinct brown (10YR 4/3) clay films and a few distinct light gray (10YR 7/2) clay depletions on faces of peds; common fine distinct grayish brown (10YR 5/2) iron depletions and few fine faint yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; very strongly acid; gradual smooth boundary. (0 to 20 inches thick)
2Btx1--34 to 44 inches; grayish brown (10YR 5/2) silty clay loam; moderate very coarse prismatic structure parting to weak coarse subangular blocky; very firm; brittle; cracks between polygons filled with light gray (10YR 7/1) silt loam; common coarse prominent yellowish brown (10YR 5/8) masses of iron accumulation in the matrix; common coarse dark red (2.5YR 3/6) and brown (7.5YR 4/4) weakly cemented iron-manganese nodules, and few fine black (10YR 2/1) iron-manganese concretions; about 12 percent sand; very strongly acid; gradual smooth boundary.
2Btx2--44 to 50 inches; brown (10YR 5/3) loam; weak very coarse prismatic structure parting to weak coarse subangular blocky; very firm; brittle; few vertical streaks and cracks between polygons filled with light gray (10YR 7/1) silt; common coarse distinct dark yellowish brown (10YR 4/4) masses of iron accumulation and common fine faint grayish brown (10YR 5/2) iron depletions in the matrix; few black (10YR 2/1) iron-manganese concretions; about 30 percent sand; very strongly acid; gradual smooth boundary. (Combined thickness of the Btx horizons is 10 to 36 inches.)
2C--50 to 60 inches; brown (10YR 5/3) loam; massive, friable; common medium faint grayish brown (10YR 5/2) iron depletions in the matrix; strongly acid.
TYPE LOCATION: Edwards County, Illinois; about 10 miles north and 3 miles west of Albion; 925 feet south and 1,575 feet west of northeast corner of sec. 17, T. 1 N., R. 10 E.; USGS West Salem, Illinois, topographic quadrangle; lat. 38 degrees 31 minutes 24 seconds N., and long. 88 degrees 07 minutes 05 seconds W.; UTM Zone 16S, 402960 Easting 4263410 Northing; NAD 27.
RANGE IN CHARACTERISTICS: The depth to the base of soil development is greater than 48 inches. The depth to the second sequum (Bt/E or B't horizon) is 20 to 30 inches. The depth to the top of the fragipan ranges from 25 to 40 inches. The particle-size control section averages 24 to 35 percent clay.
The Ap or The Ap or A horizon has hue of 10YR, value of 4 or 5, and chroma of 2 or 3. It is silt loam, except some eroded pedons are silty clay loam. Reaction is very strongly acid or strongly acid except where limed.
The E or EB horizon has hue of 10YR, value of 4 or 5, and chroma of 3 to 6. It has been mixed with the surface layer in some eroded pedons. Reaction is very strongly acid or strongly acid except where limed.
The Bt and Bt horizons have hue of 7.5YR or 10YR, value of 4 to 6, and chroma of 3 to 6. They are silty clay loam or silt loam. Redoximorphic iron depletions are in the lower part. Reaction is strongly acid or very strongly acid.
The Bt/E horizon is strongly acid or very strongly acid. The Bt part has hue of 10YR or 7.5YR, value of 4 to 6, and chroma of 3 to 6. The peds of Bt are silty clay loam or silt loam and have subangular blocky or prismatic structure. The E part has hue of 10YR, value of 5 to 8, and chroma of 1 to 4. The E material on the faces of the peds and filling interstices is silt loam or silt.
The Btx or 2Btx horizon has hue of 10YR or 7.5YR, value of 4 to 6, and chroma of 2 to 8 and has redox features. It is silt loam, silty clay loam, loam, or clay loam. Clay content ranges from 20 to 35 percent and sand content ranges from 10 to 30 percent sand in some or all parts above a depth of 60 inches. Reaction is strongly acid or very strongly acid. The content of rock fragments ranges from 0 to 4 percent. The primary structure is very coarse prismatic and the polygons are separated or surrounded by cracks filled with silt or silt loam that has grayer color or higher color value, and typically less clay, than the interiors of the polygons.
The 2C or 2Btb horizon has hue of 10YR or 7.5YR, value of 4 to 6, and chroma of 2 to 6, and has redox features. Reaction is moderately acid to very strongly acid. It is loam, silt loam, clay loam or silty clay loam.
COMPETING SERIES: These are the Apalono, Bedford, Cincinnati, Fountainville, Grantsburg, Hildebrecht, Hosmer, Nicholson, Omulga, Otwell, Otwood, Solsberry, Weisburg, and Zanesville series in the same family and the Boston and Lawrenceville series in closely related family (cation exchange activity class not assigned). Apalono, Bedford and Nicholson soils average more than 35 percent clay in the lower part of the series control section. Cincinnati, Hildebrecht and Solsberry soils have a horizon that contains 4 percent or more rock fragments within a depth of 60 inches. Fountainville and Zanesville soils have a lithic contact within 80 inches. Grantsburg and Hosmer soils average less than 10 percent sand to a depth of 60 inches. Omulga and Otwell soils have subhorizons in the lower part of the series control section that have as much as 50 percent sand. Otwood soils contain mica flakes throughout the series control section. Weisburg soils have more than 40 percent clay in the lower part of the series control section. Boston soils average more than 35 percent clay in the lower part of the series control section. Lawrenceville soils have rock fragments in the upper part of the series control section.
GEOGRAPHIC SETTING: Ava soils are on convex ridges, shoulders and backslopes on loess-covered dissected till plains. Slope gradients are 0 to 18 percent. Ava soils formed in 30 to 55 inches of loess (considered to be of Wisconsin age) and in the underlying silty or loamy deposits. The underlying deposits contain more sand than the overlying loess mantle and consist of erosional sediments or reworked material of the A horizon of the paleosol and an admixed amount of earliest Wisconsinan loess. Locally these soils often contain a band of pebbles of the Illinoian till concentrated by erosion. Ava soils are underlain, at a depth of about 4 to 7 feet, by a strongly developed paleosol considered to be from the Illinoian till stage. The mean annual air temperature ranges from 50 to 58 degrees F., the mean annual precipitation ranges from 38 to 45 inches, frost free period ranges from 170 to 200 days, and elevation ranges from 350 to 875 feet above mean sea level.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bluford, Hickory, Parke, and Wynoose soils. The somewhat poorly drained Bluford soils are on higher lying broader summits or lower lying backslopes. The well drained Hickory soils do not have a fragipan and are on lower lying backslopes. The well drained Parke soils do not have a fragipan, have redder colors, and lower base saturation in the lower part of the solum, and are on similar convex ridges of eskers, kames, outwash plains. The poorly drained Wynoose soils are on flats of the till plains. The Bluford and Wynoose soils form a hydrosequence with Ava soils. In Indiana the Ava soils are also associated with the well drained Cincinnati, moderately well drained Shakamak, and the somewhat poorly drained Vigo soils.
DRAINAGE AND PERMEABILITY: Moderately well drained. The potential for surface runoff is high. Permeability is moderate in the upper part of the solum and very slow in the fragipan. Depth to an intermittent perched high water table is at 1.5 to 3.5 feet from January through April in most years.
USE AND VEGETATION: Many areas of Ava soils are cultivated. Corn, soybeans, small grain, and pasture are the main crops. Some areas are in woodland. Native vegetation is deciduous trees.
DISTRIBUTION AND EXTENT: Southern Illinois, South-Western Indiana, and Ohio. Ava soils are extensive (more than 500,000 acres correlated), and are mainly in MLRA's 113 and 114.
MLRA OFFICE RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Washington County, Illinois, 1927.
REMARKS: We now believe that the illuvial layer of the lower sequum (B't horizon) is the main part of the argillic horizon, and that the part of the solum that meets the current definition of a fragipan horizon is below the B't horizon. Horizon designations have been adjusted to reflect this thinking. Water is perched on the B't horizon or on the fragipan, and free water flows laterally through or above the B/E horizon.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from the surface of the soil to a depth of 14 inches (Ap, E, and BE horizons);
Argillic horizon - the zone from 14 to 50 inches (Bt, Bt/E, B't, 2Btx1 and 2Btx2 horizons);
Fragipan - the zone from 34 to 50 inches (2Btx1 and 2Btx2 horizons);
Udic moisture regime;
ADDITIONAL DATA: Data for several pedons are on file at the Illinois state office. Engineering test data for the typical pedon is published in the Soil Survey of Edwards and Richland Counties, Illinois. Also lab data from Indiana is on file at the Major Land Resource Area Office (MO11) at Indianapolis.