LOCATION HARCO IL
Established Series
Rev. MBW-JCD
08/2011
HARCO SERIES
The Harco series consists of very deep, somewhat poorly drained soils formed in silty sediments on stream terraces. Slope ranges from 0 to 3 percent. Mean annual precipitation is about 940 mm (37 inches), and mean annual temperature is about 13 degrees C (55 degrees F).
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Aquic Argiudolls
TYPICAL PEDON: Harco silt loam, in a cultivated field on a stream terrace at an elevation of about 116 meters (380 feet) above mean sea level. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 23 cm (0 to 9 inches); very dark gray (10YR 3/1) silt loam, gray (10YR 5/1) dry; weak fine granular structure; friable; many very fine roots and common worm casts; neutral; abrupt smooth boundary.
A--23 to 36 cm (9 to 14 inches); black (10YR 2/1) silt loam; very dark gray (10YR 3/1) crushed, gray (10YR 5/1) dry; moderate medium granular structure; friable; many very fine roots; few medium prominent yellowish brown (10YR 5/6) masses of oxidized iron; neutral; gradual smooth boundary. [Combined thickness of the A horizon is 25 to 46 cm (10 to 18 inches).]
BA--36 to 43 cm (14 to 17 inches); very dark gray (10YR 3/1) silt loam, grayish brown (10YR 5/2) dry; weak fine and medium subangular blocky structure; firm; many very fine roots; common fine distinct olive brown (2.5Y 4/3) very weakly cemented iron-manganese concretions; few fine prominent yellowish brown (10YR 5/6) masses of oxidized iron; neutral; clear smooth boundary. [0 to 10 cm (4 inches)]
Bt1--43 to 58 cm (17 to 23 inches); olive brown (2.5Y 4/3) silty clay loam; moderate medium subangular blocky structure; firm; common very fine roots; many distinct and prominent very dark gray (10YR 3/1) organoargillans on faces of peds and in root channels; common fine faint yellowish brown (10YR 5/4) masses of oxidized iron; common medium prominent reddish black (2.5YR 2.5/1) iron-manganese concretions; neutral; clear smooth boundary.
Bt2--58 to 79 cm (23 to 31 inches); olive brown (2.5Y 4/3) silty clay loam; weak medium prismatic structure parting to moderate medium and coarse subangular blocky; firm; common very fine roots; many distinct very dark gray (10YR 3/1) organoargillans on faces of peds and in root channels; common fine prominent yellowish brown (10YR 5/6) and common fine distinct light olive brown (2.5Y 5/6) masses of oxidized iron; few fine prominent reddish black (2.5YR 2.5/1) iron-manganese concretions; neutral; gradual smooth boundary. [15 to 30 cm (6 to 12 inches)]
Bt3--79 to 99 cm (31 to 39 inches); olive (5Y 5/3) silty clay loam; weak medium prismatic structure parting to weak medium subangular blocky; firm; few very fine roots; few faint dark grayish brown (2.5Y 4/2) clay films on vertical and horizontal faces of peds; common prominent very dark gray (10YR 3/1) organic stains in root channels; common medium distinct dark yellowish brown (10YR 4/4) and common medium prominent yellowish brown (10YR 5/6) masses of oxidized iron; few fine prominent reddish black (2.5YR 2.5/1) iron-manganese concretions; neutral; gradual smooth boundary. [Combined thickness of the Bt horizon is 35 to 79 cm (14 to 31 inches).]
C1--99 to 124 cm (39 to 49 inches); mixed grayish brown (2.5Y 5/2), light olive brown (2.5Y 5/3), and yellowish brown (10YR 5/6) silt loam; massive; friable; common fine very dark gray (10YR 3/1) clay films in root channels; few fine prominent reddish black (2.5YR 2.5/1) iron-manganese concretions; slightly effervescent; slightly alkaline; diffuse smooth boundary.
C2--124 to 155 cm (49 to 61 inches); yellowish brown (10YR 5/6) silt loam; massive; friable; common medium prominent light olive brown (2.5Y 5/3) iron depletions; strongly effervescent; moderately alkaline.
TYPE LOCATION: Gallatin County, Illinois; about 2 miles southeast of Cottonwood; 300 feet east and 1,420 feet north of the southwest corner of sec. 35, T. 7 S., R. 9 E.; lat. 37 degrees 52 minutes 06 seconds N. and long. 88 degrees 11 minutes 30 seconds W.; UTM Zone 16, 395175 easting and 4191881 northing, NAD 83.
RANGE IN CHARACTERISTICS:
Thickness of the mollic epipedon: 25 to 46 cm (10 to 18 inches)
Depth to the base of the argillic horizon: 64 to 114 cm (25 to 45 inches)
Depth to carbonates: 76 to 102 cm (30 to 40 inches)
Mean annual soil temperature: 13 to 15 degrees C (56 to 59 degrees F)
Ap or A horizon:
Hue: 10YR
Value: 2 or 3
Chroma: 1 or 2
Texture: silt loam
Sand content: ranges from 5 to 20 percent
Rock fragment content: less than 5 percent
Reaction: slightly acid or neutral
BA horizon, where present:
Hue: 10YR
Value: 3
Chroma: 1 or 2
Texture: silt loam
Sand content: ranges from 5 to 20 percent
Rock fragment content: less than 5 percent
Reaction: slightly acid or neutral
Bt horizon:
Hue: 10YR to 5Y
Value: 4 to 6
Chroma: 1 to 4
Texture: silt loam or silty clay loam
Clay content: averages 24 to 35 percent
Sand content: ranges from 5 to 20 percent
Rock fragment content: less than 5 percent
Reaction: slightly acid to neutral
Some pedons have a BC horizon.
C horizon:
Hue: 10YR to 5Y
Value: 4 to 6
Chroma: 1 to 6
Texture: silt loam
Clay content: averages 20 to 27 percent
Sand content: ranges from 5 to 20 percent
Rock fragment content: less than 1 percent
Reaction: slightly alkaline or moderately alkaline
COMPETING SERIES: These are the
Arrowsmith,
Bearpen,
Brenton,
Edwardsville,
Elburn,
Grundelein,
Hacreek,
Higginsville,
Keller,
Lafayette,
Lawndale,
Lisbon,
Lismod,
Loran,
Mundelein,
Muscatune,
Nira,
Raub,
Rooks,
Rowley and
Shannondale series. Arrowsmith soils have a mean annual soil temperature of less than 13 degrees C (56 degrees F). Bearpen, Brenton, Edwardsville, Elburn, Hacreek, Higginsville, Muscatune, Nira, and Shannondale soils are deeper than 102 cm (40 inches) to carbonates. Grundelein, Lawndale, Lisbon, Lismod, and Rowley soils have more than 20 percent sand in the lower part of the series control section. Lafayette soils contain more than 5 percent rock fragments in the lower part of the argillic horizon. Keller soils are deeper than 114 cm (45 inches) to the base of the argillic horizon. Mundelein soils are stratified in the lower part of the series control section. Loran soils have a paralithic contact within a depth of 152 cm (60 inches). Raub soils have a densic contact in the lower part of the series control section. Rooks soils average more than 27 percent clay in the lower part of the series control section.
GEOGRAPHIC SETTING: Harco soils are on stream terraces. Slope ranges from 0 to 3 percent. Harco soils formed in texturally uniform silty sediments. Mean annual precipitation ranges from 762 to 1143 mm (30 to 45 inches). Mean annual temperature ranges from 12 to 14 degrees C (54 to 57 degrees F).
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Patton and
Marissa soils. The Marissa soils have an E horizon, higher average clay content in the Bt horizon, and are on similar positions nearby. The poorly drained or very poorly drained Patton soils have more clay in the upper part of the control section and are on somewhat lower elevations.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat poorly drained. Depth to the top of a perched seasonal high water table ranges from 30 to 61 cm (1 to 2 feet) in the spring in normal years. Potential for surface runoff is low. Saturated hydraulic conductivity is moderately high. Permeability is moderate.
USE AND VEGETATION: Most areas are cropped to corn, soybeans, small grain. A few areas are pastured. Native vegetation is prairie grasses.
DISTRIBUTION AND EXTENT: MLRAs 108A, 110 and 115A. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana
SERIES ESTABLISHED: Saline County, Illinois, November 29, 1974.
REMARKS: Areas of Harco soils in MLRAs 108A and 110 will be recorrelated to Arrowsmith series when these survey areas are updated. Harco soils will be restricted to areas having a mean annual soil temperature of more than 56 degrees F.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: from the surface to a depth of 43 cm (17 inches) (Ap, A, and BA horizons).
Argillic horizon: from a depth of 43 to 99 cm (17 to 39 inches) (Bt horizon).
Aquic conditions; redoximorphic features present in the lower part of the mollic epipedon and in all underlying horizons.
National Cooperative Soil Survey
U.S.A.