LOCATION AVOCA                   MI

Established Series
Rev. RWJ-NWS-JKC
01/2017

AVOCA SERIES

The Avoca series consists of very deep, somewhat poorly drained soils that formed in sandy glaciolacustrine deposits over loamy till. Avoca soils are on till-floored lake plains, till plains, water-lain moraines, wave-worked till plains, nearshore zones and end moraines. Slope ranges from 0 to 3 percent. Mean annual precipitation is about 817 mm, and mean annual temperature is about 9 degrees C.

TAXONOMIC CLASS: Sandy over loamy, mixed, semiactive, nonacid, mesic Aquic Udorthents

TYPICAL PEDON: Avoca loamy sand, on a 2 percent slope in a pastured field at an elevation of 188 meters. (Colors are for moist soil unless otherwise noted.)

Ap--0 to 25 cm; very dark brown (10YR 2/2) loamy sand; weak medium granular structure; very friable; slightly acid; abrupt smooth boundary. (20 to 25 cm thick)

E --25 to 30 cm; grayish brown (10YR 5/2) sand; single grain; loose; slightly acid; abrupt irregular boundary. (0 to 8 cm thick)

Bw1--30 to 46 cm; brown (10YR 4/3) fine sand; weak fine subangular blocky structure; very friable; many medium prominent yellowish red (5YR 4/6), faint dark yellowish brown (10YR 4/4), and faint yellowish brown (10YR 5/4) masses of oxidized iron in the upper part; few fine distinct yellowish brown (10YR 5/6) masses of oxidized iron in the lower part; few fine faint grayish brown (10YR 5/2) iron depletions in the lower part; slightly alkaline; abrupt wavy boundary.

Bw2--46 to 66 cm; yellowish brown (10YR 5/4) fine sand; single grain; loose; many medium distinct and prominent yellowish brown (10YR 5/6 and 5/8) and distinct strong brown (7.5YR 5/6) masses of oxidized iron; many medium faint pale brown (10YR 6/3) and distinct grayish brown (10YR 5/2) iron depletions; slightly alkaline; abrupt wavy boundary. (Combined thickness of the Bw horizons is 13 to 86 cm.)

Cg1 --66 to 84 cm; light brownish gray (10YR 6/2) fine sand; single grain; loose; common medium faint grayish brown (10YR 5/2) iron depletions; common medium faint pale brown (10YR 6/3) masses of oxidized iron; about 6 percent gravel and 2 percent cobbles; slightly effervescent; moderately alkaline; abrupt wavy boundary. (0 to 51 cm thick)

2Cg2 --84 to 137 cm; grayish brown (10YR 5/2) clay loam; massive; many fine faint gray (10YR 5/1) iron depletions; many fine distinct and prominent yellowish brown (10YR 5/4 and 5/6) masses of oxidized iron; slightly effervescent; moderately alkaline.

TYPE LOCATION: St. Clair County, Michigan; 1,520 feet south and 375 feet west of the northeast corner of sec. 6, T. 7 N., R. 17 E; USGS Ruby topographic quadrangle; latitude 43 degrees 4 minutes 43.06 seconds N. and longitude 82 degrees 30 minutes 2.86 seconds W., WGS84.

RANGE IN CHARACTERISTICS:
Depth to the base of soil development: 46 to 100 cm
Depth to carbonates: 46 to 100 cm
Reaction: moderately acid to slightly alkaline in the solum

Some forested areas have thin Oa horizons.

Ap horizon or A horizon, where present:
Value: 2 to 4
Chroma: 1 to 3
Texture: loamy sand, sand, fine sand, or loamy fine sand
Rock fragment content: 0 to 13 percent

E horizon:
Value: 5 or 6
Chroma: 2 or 3
Texture: loamy sand, sand, fine sand, or loamy fine sand
Rock fragment content: 0 to 13 percent

Bw horizon:
Hue: 7.5YR or 10YR
Value: 4 or 5
Chroma: 3 to 6
Texture: sand, fine sand, or loamy sand
Rock fragment content: 0 to 13 percent

Some pedons have a BC horizon.

C horizon:
Value: 5 or 6
Chroma: 2 to 4
Texture: sand or fine sand
Rock fragment content: 0 to 13 percent

2C horizon:
Hue: 7.5YR to 2.5Y
Value: 4 or 5
Chroma: 2 to 4
Texture: loam, silt loam, clay loam, or silty clay loam
Clay content: 15 to 35 percent
Rock fragment content: 5 to 14 percent

COMPETING SERIES: This is the Rapson series. Rapson soils are derived from sandy over loamy glaciolacustrine deposits and have fewer than 5 percent rock fragments in the 2C horizon.

GEOGRAPHIC SETTING: Avoca soils are on till-floored lake plains, till plains, water-lain moraines, wave-worked till plains, nearshore zones and end moraines of Wisconsinan age. Slope ranges from 0 to 3 percent. Mean annual precipitation ranges from 758 to960 mm. Mean annual temperature ranges from 7.2 to 10.5 degrees C.

GEOGRAPHICALLY ASSOCIATED SOILS: The finer textured, somewhat poorly drained Londo, Blount, and Metamora soils and the poorly drained Parkhill soils are the most common associates of Avoca soils. The somewhat poorly drained Thetford and the poorly drained Granby soils are very deep sandy soils that are next to Avoca soils where the till borders lacustrine areas.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat poorly drained. Potential for surface runoff is low or very low. Saturated hydraulic conductivity is high in the sandy upper part and moderately high in the loamy lower part.

USE AND VEGETATION: Most of the Avoca soils have been cleared and cultivated. However, many of these areas are now idle or in permanent pasture. Cropped areas are planted to corn, small grain and hay. Some small woodlots remain and have second growth stands of elm, soft maple, aspen and white birch. Native vegetation is mixed northern hardwoods and white pine.

DISTRIBUTION AND EXTENT: MLRA 99. This series is of moderate extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: AMHERST, MASSACHUSETTS

SERIES ESTABLISHED: St. Clair County, Michigan, 1969.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: from the surface to a depth of 25 cm (Ap horizon).
Albic horizon: from a depth of 25 to 30 cm (E horizon).
Lithologic discontinuity: at 84 cm (top of the 2C horizon).
Aquic conditions: 40 cm to 137 cm (Bw1, Bw2, Cg1, and 2Cg2 horizons).

Some pedons have been described with a Bs horizon that contains up to 30% fragments of cemented soil material similar in appearance to weakly cemented ortstein. These areas require further study to characterize the cementing agent and soil chemistry of the profile.

A dense substratum phase is recognized.

A phase with a surface layer of human transported materials has been correlated. This layer is less than 50 cm thick and of variable textures.

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National Cooperative Soil Survey
U.S.A.