LOCATION MHOON LA+AR KY MO MS TN

Established Series
Rev. JWP-WLC-MAV
01/2018

MHOON SERIES

The Mhoon series consists of very deep, poorly drained, slowly permeable soils that formed in loamy Mississippi River alluvial sediments. These soils are on level or nearly level alluvial plains of the Mississippi River and its distributaries. Slope is dominantly less than 1 percent but ranges up to 5 percent.

TAXONOMIC CLASS: Fine-silty, mixed, superactive, nonacid, thermic Fluvaquentic Endoaquepts

TYPICAL PEDON: Mhoon silt loam--cultivated field. (Colors are for moist soil unless otherwise stated.)

Ap--0 to 6 inches; dark gray (10YR 4/1) silty clay loam; weak medium granular structure; very friable; neutral; clear smooth boundary. (4 to 14 inches thick)

Bg1--6 to 14 inches; gray (10YR 5/1) silty clay loam; few medium distinct dark yellowish brown (10YR 4/4) mottles; weak fine subangular blocky structure; very friable; neutral; abrupt smooth boundary. (4 to 10 inches thick)

Bg2--14 to 20 inches; dark gray (10YR 4/1) silty clay loam, few medium distinct dark yellowish brown (10YR 4/4) mottles; weak medium subangular blocky structure; firm, sticky, plastic; neutral; clear smooth boundary. (4 to 30 inches thick)

Bg3--20 to 38 inches; gray (10YR 6/1) silt loam, common medium distinct dark yellowish brown (10YR 4/4) mottles; weak fine subangular blocky structure; very friable; neutral; abrupt smooth boundary. (0 to 20 inches thick)

Cg--38 to 60 inches; gray (10YR 5/1) silty clay loam, few medium distinct dark yellowish brown (10YR 4/4) mottles; massive; firm, sticky, plastic; neutral.

TYPE LOCATION: West Baton Rouge Parish, Louisiana; 1 mile west of Chamberlin on parish road, sec. 57 T. 6 S., R. 11 E.

RANGE IN CHARACTERISTICS: Solum thickness ranges from about 20 to 50 inches.

The A horizon is dark gray (10YR 4/1; N 4/0), dark grayish brown (10YR 4/2; 2.5Y 4/2), very dark gray (10YR 3/1; N 3/0), or very dark grayish brown (10YR 3/2). Colors of 3 value are limited to A horizons that are less than 6 inches thick. It is silt loam or silty clay loam, and slightly acid through slightly alkaline.

The Bg horizons are dark gray (10YR 4/1; N 4/0; 5Y 4/1), gray (10YR 5/1, 6/1; 5Y 5/1), or olive gray (5Y 5/2, 4/2) with brownish mottles. It is stratified silt loam, clay loam, silty clay loam, or silty clay and averages between 25 and 35 percent clay and 10 to 30 percent sand that is dominantly very fine sand. The B horizon is slightly acid through moderately alkaline.

The Cg horizon has the same color, texture, and reaction range as the Bg horizon except that in some pedons, it averages more than 35 percent clay.

COMPETING SERIES: There are no series in this family. Soils in closely related families include the Commerce, Convent, Rosebloom, Waverly, and Wehadkee series. Commerce soils have moist layers below the water table. Convent soils contain less than 18 percent clay. Rosebloom and Waverly soils are strongly to very strongly acid in the 10 to 40 inch control section. Waverly soils also have less than 18 percent clay in the control section and are in an active CE activity class. Wehadkee soils have more than 15 percent fine and coarser sand.

GEOGRAPHIC SETTING: Mhoon soils are on nearly level to slightly depressed flood plains. Slope gradients are 0 to 5 percent. The soil formed from fairly recent alkaline Mississippi River alluvium of mixed mineralogy. Most areas are protected from floods by levees. The climate is warm and humid. Mean annual precipitation is about 54 inches, and mean annual temperature is 68 degrees F., average January temperature is 53 degrees, and average July temperature is 82 degrees F, near the type location.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Commerce, Convent, Newellton, Sharkey, and Tunica series. Commerce soils have moist layers below the water table. Convent soils have less than 18 percent clay in the control section. Newellton and Tunica soils have clayey upper horizons overlying loamy horizons. Sharkey soils are clayey throughout.

DRAINAGE AND PERMEABILITY: Poorly drained; slow runoff; slow permeability. Flooding is frequent to none. The water table is at 0 to 3 feet during the winter and spring and all underlying layers are wet. Some areas are subject to ponding.

USE AND VEGETATION: Most areas are cleared and used for growing cotton, soybeans, sugarcane, small grain, corn, and pasture.

DISTRIBUTION AND EXTENT: Throughout the lower Mississippi River Delta in Louisiana, Mississippi, Arkansas, and Tennessee. The series is of large extent.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: AUBURN, ALABAMA

SERIES ESTABLISHED: USDA Sugarcane Experiment Station, Terrebonne Parish, Louisiana; 1948.

REMARKS: The Mhoon series was formerly classified in the Alluvial great soil group. Series classification changed from Typic Fluvaquents to Fluvaquentic Endoaquepts in 2002. CE activity class of superactive also assigned in 2002. Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - the zone from 0 to 6 inches (Ap).

Cambic horizon - the zone from 6 to 38 inches (Bg1, Bg2, Bg3).

Aquic conditions - in all layers during the winter and spring.

National Cooperative Soil Survey
U.S.A.