LOCATION LAKOMA SD+NE

Established Series
Rev. RFS-CJH, NJ
06/2013

LAKOMA SERIES

The Lakoma series consists of moderately deep, well drained soils formed in residuum weathered from clayey marine shale of the Pierre Shale Formation. Lakoma soils are on dissected upland plains and hills. Slopes range from 2 to 30 percent. Mean annual precipitation is about 480 millimeters (19 inches), and mean annual air temperature is about 8 degrees C (47 degrees F).

TAXONOMIC CLASS: Fine, smectitic, mesic Vertic Calciustepts

TYPICAL PEDON: Lakoma silty clay - on a west-facing convex slope of 6 percent in a cultivated field. When described the soil was dry throughout. (Colors are for dry soil unless otherwise stated)

Ap--0 to 13 centimeters (0 to 5 inches); dark grayish brown (2.5Y 4/2) crushing to grayish brown (2.5Y 5/2) silty clay, very dark grayish brown (2.5Y 3/2) crushing to dark grayish brown (2.5Y 4/2) moist; moderate fine granular structure; slightly hard, firm, sticky and very plastic; few fragments of shale; strong effervescence; moderately alkaline; clear smooth boundary. [10 to 15 centimeters(4 to 6 inches) thick]

Bw--13 to 30 centimeters (5 to 12 inches); grayish brown (2.5Y 5/2) rubbed to light brownish gray (2.5Y 6/2) silty clay, dark grayish brown (2.5Y 4/2) rubbed to grayish brown (2.5Y 5/2) moist; weak medium prismatic structure parting to weak medium and fine subangular blocky; hard, firm, very sticky and very plastic; common fragments of shale; strong effervescence; moderately alkaline; clear smooth boundary. [15 to 30 centimeters (6 to 12 inches) thick]

Bk--30 to 56 centimeters (12 to 22 inches); grayish brown (2.5Y 5/2) rubbed to light brownish gray (2.5Y 6/2) silty clay, dark grayish brown (2.5Y 4/2) rubbed to grayish brown (2.5Y 5/2) moist; weak medium blocky structure parting to weak fine and medium subangular blocky; hard, firm, very sticky and very plastic; many weathered fragments of shale; few medium accumulations of carbonate; strong effervescence; moderately alkaline; clear smooth boundary. [0 to 30 centimeters (0 to 12 inches) thick]

C--56 to 71 centimeters (22 to 28 inches); light brownish gray (2.5Y 6/2) silty clay, grayish brown (2.5Y 5/2) moist; massive; hard, firm, sticky and plastic; 40 percent by volume of partially weathered fragments of shale; few medium accumulations of carbonate; strong effervescence; moderately alkaline; clear smooth boundary. [10 to 25 centimeters(4 to 10 inches) thick]

Cr--71 to 152 centimeters (28 to 60 inches); light brownish gray (2.5Y 6/2) shale; grayish brown (2.5Y 5/2) moist; common gypsum crystals in upper part of bedded shale; violent effervescence in seams only; moderately alkaline.

TYPE LOCATION: Tripp County, South Dakota; about 3 miles south and 1 mile east of Ideal; 225 feet west and 75 feet north of the SE corner of sec. 35, T. 101 N., R. 76 W; latitude. 43 degrees 30 minutes 0.736 seconds N. and longitude. 99 degrees 52 minutes 56.646 seconds W., NAD83.

RANGE IN CHARACTERISTICS:

Soil Moisture Control Section:
The soil moisture control section is moist in some parts from April to July; intermittently moist from October to March; driest in August and September; typic ustic moisture regime.
Mean Annual Soil Temperature: 8 to 11 degrees C (46 to 52 degrees F)

Particle Size Control Section (weighted average):
Clay content: 45 to 60 percent
Sand content: 3 to 15 percent

Depth to paralithic contact: 50 to 100 centimeters (about 20 to 40 inches)

Fragments: The soil contains partially weathered fine shale fragments throughout, ranging from about 5 to 20 percent by volume in the solum and up to 70 percent in the C horizon.

A Horizon:
Hue: 10YR or 2.5Y
Value: 4 to 6 dry and 3 to 5 moist
Chroma: 2 or 3
Texture: silty clay or clay
Clay content: 45 to 60 percent
Sand content: 1 to 5 percent
Reaction: slightly or moderately alkaline
The color is as dark or darker than 5.5 dry and 3.5 moist in some pedons, but the horizon is less than 4 inches thick.

Bw Horizon:
Hue: 10YR or 2.5Y
Value: 5 or 6 dry and 4 or 5 moist
Chroma: 2 to 4
Texture: silty clay or clay
Clay content: 45 to 60 percent
Sand content: 1 to 5 percent
Reaction: slightly or moderately alkaline

Bk Horizon:
Hue: 10Yr or 2.5Y
Value: 5 to 7 dry and 4 to 6 moist
Chroma: 2 to 4
Texture: silty clay or clay
Clay content: 45 to 60 percent
Sand content: 1 to 5 percent
Reaction: slightly or moderately alkaline
Concentrations: dissemninated carbonate and accumulations of carbonate
Calcium Carbonate Equivalent ranges from 15 and 30 percent

C Horizon (or Ck where present):
Hue: 10YR or 2.5Y
Value: 5 to 7 dry and 4 to 6 moist
Chroma: 2 to 4
Texture: clay or silty clay (can range from para-channery to extremely para-channery)
Clay content: 45 to 60 percent
Sand content: 1 to 5 percent
Fragments: ranges from 10 to 70 percent partially weathered fragments of shale
Concentrations: The interior of the fragments of shale contain carbonates in some pedons. Calcium carbonate, calcium sulfate, and other salts are along the bedding planes.
Reaction: slightly or moderately alkaline
Calcium Carbonate Equivalent ranges from 15 and 30 percent

Cr Horizon:
This horizon is made up of shale. It typically has seams of gypsum up to 10 mm (4 inches) wide. It is slightly or moderately alkaline. This horizon is weakly cemented. It is formed from the Pierre Shale Formation.

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING:
Parent Material: residuum weathered from clayey marine shale of the Pierre Shale Formation
Landscape: level to steep uplands
Landform: undulating and dissected plains and hills
Slope: 2 to 30 percent
Slope shape: plane to convex
Mean annual air temperature: 7 to 10 degrees C (45 to 50 degrees F)
Mean annual precipitation: 380 to 580 millimeters (15 to 23 inches)

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Boro, Okaton, and Promise soils. Boro and Promise soils do not have a paralthic contact above 100 cm and are on similar landscapes below the Lakoma soils. Okaton soils are on steeper, more convex slopes. Okaton soils have shale at depths less than 50 centimeters (about 20 inches).

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage: well drained
Saturated Hydraulic Conductivity: moderately low
Runoff: medium to very high depending on slope.

USE AND VEGETATION: Used for native pasture, hayland, or cropland. Winter wheat, grain sorghum, oats and alfalfa are the main crops. Western wheatgrass, green needlegrass, little bluestem, big bluestem, needleandthread, and sideoats grama are the major native grasses.

DISTRIBUTION AND EXTENT:
West-central South Dakota and north central Nebraska. The series is mapped extensively in MLRA's 63A, 63B and 66.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado

SERIES ESTABLISHED:
Hughes County, South Dakota, 1970.

REMARKS: Diagnostic horizons and features recognized in this pedon are: ochric epipedon - the zone from the surface of the soil to a depth of 13 centimeter [5 inches (Ap horizon)]; cambic horizon - the zone from 13 to 30 centimeters [5 to 12 inches (Bw horizon)]; calcic horizon the zone from 30 to 71 centimeters [12 to 28 inches (Bk and C horizons)]; paralithic contact the zone from 71 to 152 centimeters [28 to 60 inches (Cr horizon)].

NCJ 5/2013 Overall update of Range in Characteristics, competing series, diagnostic features and change to tabular format.

ADDITIONAL DATA:
KSSL Pedon Numbers: 78P0363, 83P0564
User Pedon ID Number: 78SD053100, 82SD085022

National Cooperative Soil Survey
U.S.A.