LOCATION LIGAI AZ+NMEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Aridic Argiustolls
TYPICAL PEDON: Ligai extremely flaggy very fine sandy loam -- on a slightly convex backslope sloping 61 percent to the south at 8,880 feet elevation -- woodland. (Colors are for dry soil unless otherwise noted. When described, the profile was dry throughout.)
A--0 to 2 inches; reddish brown (5YR 4/3) extremely flaggy very fine sandy loam, dark reddish brown (5YR 3/2) moist; weak thick platy structure parting to moderate medium granular; soft, very friable, slightly sticky and nonplastic; few medium and common fine and very fine roots; common very fine irregularly shaped pores; 40 percent flagstones, 10 percent stones, 10 percent channers, and 10 percent gravel; neutral (pH 6.8); clear smooth boundary. (2 to 4 inches thick)
Bt--2 to 7 inches; reddish brown (5YR 4/3) very flaggy sandy clay loam, dark reddish brown (5YR 3/3) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few coarse and fine and common medium and very fine roots; few fine and very fine tubular pores; few faint clay films on faces of peds and lining pores; 20 percent gravel, 15 percent flagstones, 5 percent cobble, and 5 percent channers; neutral (pH 6.6); clear smooth boundary. (5 to 13 inches thick)
Btk1--7 to 16 inches; reddish brown (5YR 5/4) very flaggy sandy clay loam, dark reddish brown (5YR 3/3) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few coarse and common medium, fine, and very fine roots; few very fine tubular pores; common faint clay films on faces of peds and on rock fragments; 25 percent flagstones, 10 percent gravel, 5 percent cobble, and 5 percent stones; noneffervescent in fine earth, strongly effervescent on undersides of rock fragments where secondary calcium carbonate is segregated as common medium irregularly shaped accumulations; neutral (pH 7.2); gradual wavy boundary. (9 to 19 inches thick)
Btk2--16 to 25 inches; reddish brown (5YR 5/4) extremely flaggy sandy clay loam, dark reddish brown (5YR 3/4) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common medium and few coarse, fine, and very fine roots; few fine and very fine irregularly shaped pores; common faint clay films on faces of peds and on rock fragments; 35 percent flagstones, 15 percent cobble, 10 percent stones, and 10 percent gravel; noneffervescent in fine earth, violently effervescent on undersides of rock fragments where secondary calcium carbonate is segregated as common medium irregularly shaped accumulations; slightly alkaline (pH 7.6); abrupt irregular boundary. (0 to 14 inches thick)
R--25 inches; quartz diorite.
TYPE LOCATION: Apache County, Arizona; on the Navajo Indian Reservation about 7.5 miles southwest of Teec Nos Pos; 1,125 feet east and 50 feet south of the northwest corner of section 31, T.40 N., R.30 E.; Latitude 36 degrees 50 minutes 19 seconds North and Longitude 109 degrees 10 minutes 15 seconds West.
RANGE IN CHARACTERISTICS:
Soil moisture - The soil moisture control section is moist in all parts during the 60 days following the winter solstice. It is moist in all parts more than 40 percent of the time when the soil temperature at 20 inches is above 41 degrees F. December and August are the wettest months and May and June are the driest. Aridic ustic soil moisture regime.
Soil temperature - 47 to 50 degrees F
Depth to bedrock - 20 to 40 inches
Reaction - neutral in upper horizons and neutral to slightly alkaline below
Depth to base of mollic epipedon - 7 to 18 inches
Depth to base of Argillic horizon - 20 to 40 inches
Clay content - control section weighted average is 20 to 27 percent
Rock fragments - control section weighted average is 35 to 80 percent
A horizon
Hue: 5YR, 7.5YR
Value: 4 or 5 dry, 3 or 4 moist
Organic carbon content: 1.2 to 2.4 percent
Rock fragments: 60 to 80 percent
20 to 25 percent gravel and channers
35 to 40 percent flagstones
0 to 5 percent cobble
5 to 10 percent stones
Bt horizon
Hue: 5YR, 7.5YR
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 3 through 6, dry or moist
Rock fragments: 35 to 60 percent
10 to 15 percent gravel and channers
25 to 35 percent flagstones
0 to 10 percent stones
Btk horizons
Hue: 5YR, 7.5YR
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 3 through 6, dry or moist
Calcium carbonate equivalent: 0 to 3 percent
Rock fragments: 35 to 80 percent
10 to 25 percent gravel and channers
25 to 45 percent flagstones
0 to 10 percent stones
Some pedons do not have calcium carbonate accumulations.
COMPETING SERIES: These are the Golondrina (NM), Irock (NM), Jumbopeak (NV), Majada (NM), Mokiak (UT), Montoso (NM), Murdo (SD), Nederland (CO), Purcella (NM), Romine (NM), Salas (NM), Wandurn (NM), Wheelerwell (NV) and Willowman (WY) series. Golondrina, Majada, Montoso, Murdo, Nederland, Purcella, Romine, and Willoman soils are very deep. Montoso soils have strongly contrasting layers of cinders between 12 and 32 inches (The concept of Montoso should be reexamined and possibly reclassified as Loamy over pumiceous or cindery). Murdo soils have sola 10 to 20 inches thick over horizons of strongly contrasting sands and gravel (The concept of Murdo should be reexamined and possibly reclassified as Loamy-skeletal over sandy or sandy-skeletal). Irock, Mokiak, and Salas soils are moderately deep to a lithic contact of gneiss or schist bedrock. Jumbopeak soils are moderately deep to a paralithic contact of gneiss and schist. Wandurn soils are deep to a lithic contact of monzonite. Wheelerwell soils are moderately deep to a lithic contact of dolomite.
GEOGRAPHIC SETTING: Ligai soils are on backslopes of mountains. They formed in colluvium and residuum derived from Tertiary quartz diorite and sandstone. Slopes are 35 to 70 percent. Elevation ranges from 7,000 to 9,000 feet. The mean annual precipitation is 14 to 18 inches with about half falling as winter snow and half falling as rain from high- intensity convective thunderstorms between July and September. The mean annual air temperature is 45 to 48 degrees F. The frost-free period is 120 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bigpaw, Pastorpeak, and Zibetod soils. Bigpaw soils are very deep, fine-silty, and occur on toeslopes below domes. Pastorpeak soils are very deep, have thick mollic epipedons, and occur on adjacent north-facing backslopes. Zibetod soils are shallow, have mollic epipedons, and occur on footslopes and shoulders of domes.
DRAINAGE AND PERMEABILITY: Well drained; rapid runoff; moderate permeability.
USE AND VEGETATION: Ligai soils are used for livestock grazing and fuelwood production. Present vegetation is pinyon with an understory of muttongrass, bottlebrush squirreltail, earth sedge, black sagebrush, Utah serviceberry, Gambel oak, mountain snowberry, and fendlerbush.
DISTRIBUTION AND EXTENT: Ligai soils are of moderate extent on the Carrizo Mountains portion of the Colorado Plateau province in northeast Arizona. MLRA is 39.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Shiprock Area, Parts of San Juan County, New Mexico and Apache County, Arizona; 1993.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from 0 to 16 inches (A, Bt, Btk1 horizons)
Argillic horizon - The zone from 2 inches to 25 inches (Bt, Btk1, Btk2 horizons)
Lithic contact - The boundary at 25 inches (R horizon)
Keys to Soil Taxonomy - Soils classified according to Keys to Soil Taxonomy Tenth Edition, 2006.
Classification changed from a Typic to an Aridic subgroup in 2006. The revised classification is consistent with the soil moisture regime assigned.