LOCATION MOCO AZEstablished Series
TAXONOMIC CLASS: Fine-loamy, gypsic, thermic Calcic Argigypsids
TYPICAL PEDON: Moco fine sandy loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 1 inch; brown (7.5YR 5/4) fine sandy loam, brown (7.5YR 4/4) moist; weak thin platy structure; soft, very friable, nonsticky and nonplastic; few very fine roots; few fine irregular pores; strongly effervescent, 2 percent calcium carbonate equivalent and 1 percent gypsum; moderately alkaline (pH 8.2); abrupt smooth boundary. (1 to 4 inches thick)
Btk--1 to 10 inches; brown (7.5YR 4/4) clay loam, dark brown (7.5YR 3/4) moist; weak fine subangular blocky structure; soft, very friable, moderately sticky and moderately plastic; common very fine and fine roots; few fine tubular pores; few distinct clay films on ped faces; few fine calcium carbonate filaments; strongly effervescent, 10 percent calcium carbonate equivalent and 3 percent gypsum; moderately alkaline (pH 8.2); clear smooth boundary. (5 to 12 inches thick)
Btky--10 to 20 inches; brown (7.5YR 4/4) clay loam, strong brown (7.5YR 5/6) moist; moderate fine subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine and fine roots; few fine irregular pores; common distinct clay films on ped faces; common fine soft calcium carbonate and gypsum masses; strongly effervescent, 19 percent calcium carbonate equivalent and 4 percent gypsum; moderately alkaline (pH 8.2); abrupt smooth boundary. (10 to 15 inches thick)
Bky1--20 to 31 inches; 70 percent light brown (7.5YR 6/4) and 30 percent pinkish white (7.5YR 8/2) clay loam, light brown (7.5YR 6/4) moist; weak fine subangular blocky structure; soft, very friable, moderately sticky and moderately plastic; common very fine and fine roots; few fine tubular and irregular pores; common fine soft calcium carbonate and gypsum masses; 6 percent petronodes; violently effervescent, 50 percent calcium carbonate equivalent and 8 percent gypsum; moderately alkaline (pH 8.4); clear smooth boundary.
Bky2--31 to 48 inches; 70 percent brown (7.5YR 5/4) and 30 percent pinkish white (7.5YR 8/2) clay loam, pink (7.5YR 7/4) moist; weak fine and medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; few very fine roots; few fine tubular and irregular pores; many fine and medium soft and hard calcium carbonate and gypsum masses; 10 percent petronodes; violently effervescent, 47 percent calcium carbonate equivalent and 10 percent gypsum; moderately alkaline (pH 8.4); abrupt smooth boundary.
Bky3--48 to 60 inches; 70 percent pinkish gray (7.5YR 7/2) and 30 percent pinkish white (7.5YR 8/2) clay loam, light gray (10YR 7/2) moist; massive; slightly hard, friable, moderately sticky and moderately plastic; few very fine roots; few fine tubular and irregular pores; many fine and medium soft and hard calcium carbonate and gypsum masses; violently effervescent, 47 percent calcium carbonate equivalent and 10 percent gypsum; moderately alkaline (pH 8.4). (Combined thickness of the Bky horizons is 30 to 42 inches)
TYPE LOCATION: Cochise County, Arizona; located at a latitude of 31 degrees, 26 minutes, 15 seconds North and longitude of 110 degrees, 07 minutes, 10 seconds West; about 1500 feet east and 1200 feet south from the northwest corner of Section 16, T. 23 S., R. 22 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. Ustic aridic soil moisture regime.
Soil Temperature: 62 to 69 degrees F.
Petronodic feature: 5 to 20 percent petronodes at moderate depths. Petronodes are thought to have formed from calcium and magnesium the precipitated out during fluctuating seasonal water tables under a climate much wetter than the present. Repeated wetting and extreme drying of the soils have been a factor in nodule development. The petronodes have no internal organization and break down completely in HCL acid but not in water.
Rock fragments: 0 to 35 percent hardpan fragments and/or petronodes
Reaction: slightly to moderately alkaline
Clay content: 18 to 35 percent
Depth to calcic horizon: 5 to 20 inches
Depth to gypsic horizon: 20 to 60 inches
Gypsum content: 1 to 20 percent
A horizon
Hue: 7.5YR, 10YR
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 3 or 4, dry or moist
Calcium carbonate equivalent: 0 to 5 percent
Btk and Btky horizons
Hue: 7.5YR, 5YR
Value: 4 or 5 dry, 3 through 5 moist
Chroma: 4 or 6, dry or moist
Texture: sandy clay loam, clay loam, loam
Calcium carbonate equivalent: 5 to 30 percent
Bky horizon
Hue: 7.5YR, 10YR
Value: 5 through 8, dry or moist
Chroma: 2 through 4, dry or moist
Texture: loam, clay loam, silty clay loam
Calcium carbonate equivalent: 30 to 55 percent
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Moco soils are on basin floors at elevations of 3,800 to 4,800 feet. Slopes range from 1 to 5 percent. These soils formed in mixed fan alluvium. The mean annual precipitation is 12 to 16 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 67 degrees F. The frost-free period is 180 to 230 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Libby, Gulch, Major, Sasabe, Reeup and Kaboom soils. Kaboom soils contain interbedded bedrock. Libby, Sasabe and Reeup soils are fine textured. Major soils do not have argillic horizons. Gulch soils do not have gypsic horizons.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderately slow permeability.
USE AND VEGETATION: Used for livestock grazing and wildlife habitat. Vegetation includes mesquite, sacaton, catclaw acacia, tobosa, blue grama and yucca.
DISTRIBUTION AND EXTENT: Southern Arizona. Moco soils are of moderate extent. MLRA is 41.
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 1 inch (A horizon)
Argillic horizon - The zone from 1 to 20 inches (Btk, Btky horizons)
Calcic horizon - The zone from 10 to 20 inches (Btky horizon)
Gypsic horizon - The zone from 20 to 60 inches (Bky1, Bky2, Bky3 horizons)
Soil Taxonomy Second Edition, 1999