LOCATION CONTENTION AZEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Typic Gypsitorrerts
TYPICAL PEDON: Contention silt loam - rangeland. (Colors are for dry soil unless otherwise noted.) 10 to 20 percent of the surface is covered with gravel, cobble, hardpan fragments and/or limestone. Continuous cracks from the surface to 26 inches ranging from 1/8 to 1 1/2 inches wide.
A--0 to 3 inches; reddish brown (5YR 5/3) silt loam, reddish brown (5YR 5/3) moist; weak fine granular structure; loose, moderately sticky and very plastic; common very fine and fine roots; many very fine tubular pores; violently effervescent; moderately alkaline (pH 8.0); abrupt smooth boundary. (1 to 3 inches thick)
Bky1--3 to 11 inches; reddish brown (5YR 4/3) silty clay, reddish brown (5YR 5/3) moist; moderate medium subangular blocky structure; soft, firm, very sticky and very plastic; common very fine and fine roots; few fine tubular pores; common very fine soft calcium carbonate and gypsum masses; few fine gypsum crystals throughout; violently effervescent, 12 percent calcium carbonate equivalent and 15 percent gypsum; slightly alkaline (pH 7.6); abrupt smooth boundary.
Bky2--11 to 21 inches; reddish brown (5YR 5/3) clay, reddish brown (5YR 5/3) moist; strong medium angular blocky structure with weak medium wedges; hard, firm, very sticky and very plastic; few very fine roots; few fine tubular pores; common fine gypsum crystals in clusters on ped faces; few very fine soft calcium carbonate and gypsum masses; few light yellowish brown (2.5Y 6/3) relict redox features; violently effervescent, 12 percent calcium carbonate equivalent and 15 percent gypsum; slightly alkaline (pH 7.8); abrupt smooth boundary. (Combined thickness of the Bky horizons is 10 to 22 inches)
Bssky1--21 to 34 inches; reddish brown (5YR 5/3) clay, reddish brown (5YR 5/3) moist; strong medium angular blocky parting to strong fine angular blocky structure and weak medium and fine wedges; hard, firm, very sticky and very plastic; few very fine roots matted between ped faces; few fine tubular pores; common fine gypsum crystals in clusters on ped faces and in seams; few very fine soft calcium carbonate and gypsum masses; common distinct pressure faces and slickensides; violently effervescent, 15 percent calcium carbonate equivalent and 15 percent gypsum; moderately alkaline (pH 8.4); abrupt smooth boundary.
Bssky2--34 to 60 inches; reddish brown (5YR 5/3) clay, reddish brown (5YR 5/3) moist; strong medium angular blocky parting to strong fine and very fine angular blocky structure and weak medium wedges; hard, very firm, very sticky and very plastic; few very fine roots matted between ped faces; few fine and very fine gypsum crystals throughout; many distinct manganese coatings on ped faces; many distinct pressure faces and slickensides; violently effervescent, 10 percent calcium carbonate equivalent and 15 percent gypsum; slightly alkaline (pH 7.8). (Combined thickness of the Bssky horizons is 25 to 40 inches)
TYPE LOCATION: Cochise County, Arizona; located at a latitude of 31 degrees, 51 minutes, 34 seconds North and longitude of 110 degrees, 15 minutes, 11 seconds West; about 3,370 feet east and 800 feet south of the northwest corner of Section 24, T. 18 S., R. 19 E.
RANGE IN CHARACTERISTICS:
Soil moisture - Intermittently moist in some part of the soil moisture control section during July - September and December - February. Driest during May and June. Typic aridic soil moisture regime.
Soil Temperature: 62 to 70 degrees F.
Soil cracking: When dry, continuous cracks from the surface to 26 inches, ranging from 1/8 to 1/12 inches wide. Pressure faces and slickensides are common in the lower horizons.
Reaction: slightly to strongly alkaline
Clay content: greater than 35 percent in the control section
Calcium carbonate equivalent: 1 to 15 percent
Depth to gypsic horizon: 3 to 20 inches
Gypsum content: 0.5 to 15 percent
Salinity: none to moderate
Sodicity: none to slight
A horizon
Hue: 7.5YR, 5YR
Value: 4 through 6 dry, 3 to 5 moist
Chroma: 2 to 4, dry or moist
Bky horizon
Hue: 7.5YR, 5YR
Value: 4 to 6 dry, 3 through 5 moist
Chroma: 2 through 4 dry or moist
Texture: clay, silty clay, silty clay loam
Bssky horizon
Hue: 7.5YR, 5YR
Value: 4 through 6 dry, 3 through 5 moist
Chroma: 3 or 4, dry or moist
Texture: clay, silty clay, silty clay loam
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Contention soils are on dissected relict lake beds at elevations of 3,500 to 4,100 feet. Slopes range from 0 to 60 percent. These soils formed in gypsiferous and calcereous alluvium from prehistoric lakes and marshes (lacustrine deposits). The mean annual precipitation is 10 to 12 inches and occurs as thunderstorms during July to September and as gentle rains during December to February. The mean annual air temperature is 60 to 68 degrees F. The frost-free period is 190 to 260 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Monzingo, Redington, Crystalgyp, Ugyp and Borderline soils. Monzingo, Crystalgyp, Ugyp, and Borderline soils are coarse-loamy. Redington soils are sandy.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; very slow permeability.
USE AND VEGETATION: Used for livestock grazing and wildlife habitat. Vegetation includes tobosa, whitethorn, alkali sacaton, fourwing saltbush, and vine mesquite.
DISTRIBUTION AND EXTENT: Southern Arizona. Contention soils are of moderate extent. MLRA is 41, 40.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Cochise County, Arizona. Soil survey of Cochise County, Arizona, Douglas-Tombstone Part; 1996.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 3 inches (A horizon)
Gypsic horizon - The zone from 11 to 60 inches (Bky2, Bssky1, Bssky2 horizons)
Classified according to Soil Taxonomy Second Edition, 1999; Key to Soil Taxonomy, Tenth Edition, 2006.