LOCATION FORGAN OK+KS
Established Series
TLC-CPH-SLM
04/2016
FORGAN SERIES
The Forgan series consists of very deep, well drained, moderately permeable soils that formed in loamy eolian deposits of Holocene age. These nearly level soils occur on plains and interdunes of sand sheets of the Southern High Plains, Northern part (MLRA 77A). Slope ranges from 0 to 3 percent. Mean annual air temperature is about 13 degrees C (55 degrees F), and mean annual precipitation is about 460 mm (l8 in).
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Aridic Argiustolls
TYPICAL PEDON: Forgan loam--on a level linear slope in cropland at an elevation of 837 m (2746 ft). (Colors are for dry soil unless otherwise stated.)
Ap--0 to 9 cm (0 to 4 in); brown (10YR 4/3) loam, dark brown (10YR 3/3) moist; moderate fine granular structure; slightly hard, very friable; few fine roots throughout; noneffervescent; strongly acid, pH 5.3; abrupt smooth boundary. (Thickness of the A horizon is 8 to 33 cm [3 to 13 in])
Bt1--9 to 36 cm (4 to 14 in); dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; weak medium prismatic structure parting to moderate medium subangular blocky; slightly hard, friable; few fine roots throughout; few faint clay films on vertical faces of peds; few fine worm casts; noneffervescent; slightly acid, pH 6.4; clear smooth boundary.
Bt2--36 to 60 cm (14 to 24 in); grayish brown (10YR 5/2) loam, dark grayish brown (10YR 4/2) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, friable; few fine roots; common distinct clay films on vertical faces of peds; few fine worm casts; noneffervescent; slightly alkaline, pH 7.5; clear smooth boundary. (Combined thickness of the Bt horizons is 12 to 53 cm [5 to 21 in])
Btk1--60 to 82 cm (24 to 32 in); very pale brown (10YR 7/4) clay loam, light yellowish brown (10YR 6/4) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, friable; common distinct clay films on vertical faces of peds; common medium irregular carbonate masses; strongly effervescent (7 percent calcium carbonate equivalent); moderately alkaline, pH 8.3; gradual wavy boundary.
Btk2--82 to 103 cm (32 to 41 in); light yellowish brown (10YR 6/4) loam, yellowish brown (10YR 5/4) moist; weak medium prismatic structure parting to moderate medium subangular blocky; hard, friable; common distinct clay films on vertical faces of peds; common medium irregular carbonate masses; strongly effervescent (6 percent calcium carbonate equivalent), moderately alkaline, pH 8.3; clear wavy boundary. (Combined thickness of the Btk horizons is 18 to 99 cm [7 to 39 in])
2Btk1--103 to 164 cm (41 to 65 in); reddish yellow (7.5YR 6/6) fine sandy loam, strong brown (7.5YR 5/6) moist; weak coarse prismatic structure parting to weak medium subangular blocky; slightly hard, very friable; few faint clay films on vertical faces of peds; few fine thread-like carbonate masses; slightly effervescent (1 percent calcium carbonate equivalent); strongly alkaline, pH 8.5; clear smooth boundary. (Combined thickness of the 2Btk horizon is 18 to 104 cm [7 to 41 in])
2Btk2--164 to 203 cm (65 to 80 in); strong brown (7.5YR 5/6) fine sandy loam, strong brown (7.5YR 4/6) moist; weak coarse prismatic structure parting to weak medium subangular blocky; slightly hard, very friable; few faint clay films on vertical faces of peds; common fine threadlike carbonate masses; slightly effervescent (2 percent calcium carbonate equivalent); moderately alkaline, pH 8.4.
TYPE LOCATION: Beaver County, Oklahoma; about 12.5 miles west and about 1.5 miles north of Forgan; 300 ft (91 m) east and 1950 ft (594 m) south of the northwest corner of section 2, Township 5N, Range 2lE (Cimarron meridian).
USGS topographic quadrangle: Turpin, NE
Latitude: 36 degrees, 55 minutes, 49.59 seconds N
Longitude: 100 degrees, 45 minutes, 51.67 seconds W
Datum: NAD83
Decimal Degrees
Latitude: 36.9304504
Longitude: -100.7643433
UTM Easting: 342865 m
UTM Northing: 4088610 m
UTM Zone: 14S
RANGE IN CHARACTERISTICS:
Solum thickness: more than 200 cm (more than 80 in)
Thickness of mollic epipedon: 18 to 49 cm (7 to 19 in)
Thickness of the argillic horizon: 25 to 178 cm (10 to 70 in)
Depth to secondary carbonate: 10 to 203 cm (4 to 80 in)
Depth to lithologic discontinuity (where present): 100 to 203 cm (40 to 80 in)
Particle-size control section (weighted average):
Silicate clay: 18 to 35 percent
Ap horizon:
Hue: 7.5YR or 10YR
Value: 3 or 4, 2 or 3 moist
Chroma: 1 to 3 moist or dry
Texture: fine sandy loam or loam
Effervescence: none to slight
Reaction (pH): strongly acid to neutral (5.1-7.3)
Bt horizon:
Hue: 7.5YR or 10YR
Value: 3 to 6, 2 to 4 moist
Chroma: 2 to 4 moist or dry
Texture: loam, clay loam, or sandy clay loam
Effervescence: none to strong
Reaction (pH): slightly acid to slightly alkaline (6.1-7.8)
Btk horizon:
Hue: 7.5YR or 10YR
Value: 4 to 8, 3 to 6 moist
Chroma: 3 to 4 moist or dry
Texture: loam, clay loam, or sandy clay loam
Visible calcium carbonate: amount-1 to 15 percent films; kind-threads and masses
Calcium carbonate equivalent: less than 15 percent
Effervescence: slight to strong
Reaction (pH): slightly or moderately alkaline (7.4-8.4)
2Btk horizon:
Hue: 7.5YR or 10YR
Value: 5 to 8, 3 to 6 moist
Chroma: 4 to 6 moist or dry
Texture: fine sandy loam, loam, or clay loam
Visible calcium carbonate: amount-1 to 15 percent films; kind-threads and masses
Calcium carbonate equivalent: less than 15 percent
Effervescence: slight to strong
Reaction (pH): slightly alkaline to strongly alkaline (7.4-9.0)
COMPETING SERIES: These are the
Ascalon,
Belfon,
Hargreave,
Noden,
Satanta, and
Wages soils.
Ascalon soils: formed in alluvium and have up to 15 percent gravels throughout
Belfon soils: have a lithologic discontinuity within 100 cm (40 in) of soil surface
Hargreave soils: formed in sandstone residuum and have a lithic contact at 50 to 100 cm (20 to 40 in)
Noden soils: formed in alluvium and residuum, have a lithic contact from 100 to greater than 150 cm (40 to greater than 60 in), and up to 10 percent gravels throughout
Satanta soils: have slightly cooler mean annual temperature range and up to 10 percent gravels throughout
Wages soils: formed in mixed alluvium and eolian sediments, and have up to 25 percent gravels and stones in the argillic horizon
GEOGRAPHIC SETTING:
Parent material: loamy eolian sediments of Holocene age
Landscape: tablelands
Landform: plains and interdunes of sand sheets
Slope: 0 to 3 percent
Soil moisture regime: an Ustic moisture regime bordering on Aridic. The soil moisture control section is dry in some or all parts for more than 180 but less than 205 days, cumulative, in normal years. July through August and December through February are the driest months. These soils are intermittently moist in September through November and March through June.
Mean annual air temperature: 12 to 14 degrees C (53 to 57 degrees F)
Mean annual precipitation: 381 to 584 mm (15 to 23 in)
Frost free Period: 170 to 200 days
Elevation: 750 to 1250 m (2460 to 4100 ft)
Thornthwaite annual P-E Index Values: 25 to 36
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Balko (T),
Belfon,
Bigbow,
Canina,
Conlen,
Dalhart,
Eva,
Hansford,
Hugoton,
Knoblaw,
Lautz,
Optima,
Oslo,
Plack,
Sophia (T), Twichell (T),
Vorhees, Waka (T), and
Zella soils.
Balko, Twichell and
Zella soils: occur in slightly lower positions and have greater than 35 percent clay in the particle-size control section
Belfon soils: occur on similar positions and have a fine or fine silty discontinuity within 100 cm (40 in) of the soil surface
Bigbow soils: occur on similar positions, have an ochric epipedon, and have a fine or fine silty discontinuity within 100 cm (40 in) of the soil surface
Canina soils: occur on slightly higher positions, have an ochric epipedon, and a fine-silty particle-size class
Conlen soils: occur in lower positions, and have carbonatic mineralogy
Dalhart soils: occur on similar positions and have an ochric epipedon
Eva and
Vorhees soils: occur on higher positions, have an ochric epipedon, and have less than 18 percent clay in the particle-size control section
Hansford,
Knoblaw, and
Lautz soils: occur in lower playa positions, and have greater than 35 percent clay in the particle-size control section
Hugoton soils: occur in slightly lower positions, and have a fine-silty particle-size class
Optima soils: occur on higher positions, and have a sandy particle-size class
Oslo and
Sophia soils: occur in lower positions, have a fine-silty particle-size class, and have calcic horizons within 100 cm (40 in) of the soil surface
Plack soils: occur in lower positions, and have a petrocalcic horizon within 50 cm (20 in) of the soil surface
Waka soils: occur in lower drainage positions, and have a fine-silty particle-size class
DRAINAGE AND PERMEABILITY:
Drainage class: well drained
Permeability: moderate
Runoff: negligible on 0 to 1 percent slopes, and low on 1 to 3 percent slopes
USE AND VEGETATION: These soils are mainly used for crop production. Corn, winter wheat, and grain sorghum are the principal crops. A considerable acreage is irrigated. Climax rangeland vegetation is dominantly mid grasses with short grasses and includes blue grama and buffalograss, little bluestem, vine-mesquite, western wheatgrass, sideoats grama, silver bluestem, wild alfalfa, and prairie clover.
DISTRIBUTION AND EXTENT: Southwest Kansas and the Oklahoma Panhandle (MLRA 77A in LRR H). The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Stevens Co., Kansas, 2005.
REMARKS:
These soils were formerly included in the Dalhart series.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: 0 to 36 cm (0 to 14 in) (Ap and Bt1 horizons)
Argillic horizon: 9 to 103 cm (4 to 41 in) (Bt1, Bt2, Btk1 and Btk2 horizons)
Secondary Carbonates: 60 to 203 cm (24 to 80 in) (Btk and 2Btk horizons)
Series revised as part of the SDJR initiative, 2014. The pedon description was updated to agree with KSSL results. Range in Characteristics and horizon data were updated.
ADDITIONAL DATA: KSSL laboratory data, Lincoln, NE; S1999OK007001 (TL-Beaver County, OK).
Taxonomic Version: Keys to Soil Taxonomy, Twelfth Edition, 2014.
National Cooperative Soil Survey
U.S.A.