LOCATION DELMO                   NV

Established Series
Rev. EWB-SES-TM-JVC
03/2017

DELMO SERIES

The Delmo series consists of very deep, well drained soils that formed in alluvium derived from mixed granitic and volcanic rocks. Delmo soils are on fan remnants on mountain valleys. Slopes are 4 to 30 percent. The mean annual precipitation is about 330 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Clayey-skeletal, smectitic, frigid Aridic Palexerolls

TYPICAL PEDON: Delmo very stony coarse sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with about 10 percent stones, 10 percent cobbles, and 40 percent gravel.

A--0 to 8 cm; grayish brown (10YR 5/2) very stony coarse sandy loam, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; common very fine roots, common very fine tubular and interstitial pores; 10 percent stones, 10 percent cobbles, and 35 percent gravel; slightly acid (pH 6.3); clear wavy boundary. (8 to 15 cm thick)

AB--8 to 15 cm; grayish brown (10YR 5/2) very stony coarse sandy loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; hard very friable, slightly sticky and nonplastic; common very fine and fine roots; common very fine tubular and interstitial pores; 10 percent stones, 10 percent cobbles, and 35 percent gravel; slightly acid (pH 6.4); abrupt wavy boundary. (0 to 10 cm thick)

Bt1--15 to 33 cm; brown (7.5YR 5/3) very gravelly clay, dark brown (7.5YR 3/3) moist; strong medium angular blocky structure; very hard, friable, very sticky and very plastic; common very fine, fine and medium roots; common fine tubular and interstitial pores; many prominent pressure cutans on faces of peds; 5 percent stones, 5 percent cobbles, and 45 percent gravel; neutral (pH 6.6); clear wavy boundary. (15 to 25 cm thick)

Bt2--33 to 66 cm; brown (7.5YR 5/4) extremely gravelly sandy clay loam, brown (7.5YR 4/4) moist; weak coarse subangular blocky structure; very hard, friable, moderately sticky and slightly plastic; few very fine, fine and medium roots; common fine tubular and interstitial pores; common distinct clay films on faces of peds and lining pores; 10 percent stones, 10 percent cobbles, and 60 percent gravel; neutral (pH 6.7); clear wavy boundary. (15 to 50 cm thick)

Btq--66 to 152 cm; light brown (7.5YR 6/4) extremely gravelly sandy clay loam, brown (7.5YR 4/4) moist; weak coarse subangular blocky structure; hard, friable, moderately sticky and slightly plastic; few very fine and fine roots; common fine tubular and interstitial pores; common distinct clay films on faces of peds and lining pores; 50 percent weakly cemented durinodes; 10 percent stones, 10 percent cobbles, and 45 percent gravel; neutral (pH 6.7).

TYPE LOCATION: Douglas County, Nevada; in the Pine Nut Mountains; about 1,200 feet south and 500 feet east of the northwest corner of section 11, T. 12 N., R. 22 E.; USGS Pine Nut Valley 7.5 minute topographic quadrangle; 38 degrees 55 minutes 18 seconds north latitude and 119 degrees 29 minutes 22seconds west longitude, WGS84 Decimal Degrees 38.9215667 latitude, -119.4894444 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in winter and spring, dry from July through October; aridic soil moisture regime that borders on xeric.
Mean annual soil temperature: 7 to 8 degrees C.
Mollic epipedon thickness: 25 to 38 cm, includes the Bt1 horizon.
Depth to base of argillic horizon: 127 to 165 cm.
Reaction: Slightly acid or neutral.
Other features: An abrupt horizon boundary is normally present between the A or AB horizon and the Bt1 horizon accompanied by an abrupt increase in clay content of at least 20 percent. Depth to the abrupt clay increase is 13 to 25 cm.

Particle-size control section - Clay content: Averages 35 to 50 percent.
Rock fragments: 45 to 85 percent, mainly gravel. Lithology of fragments is mixed igneous rocks such as granodiorite and andesite.

A and AB horizons
Chroma: 2 or 3, dry or moist.
Clay content: 10 to 18 percent.
Organic matter content: 1 or 2 percent.

Bt1 horizon
Hue: 7.5YR or 10YR.
Texture: Very gravelly clay, extremely gravelly clay, or extremely gravelly clay loam.
Clay content: 35 to 50 percent.
Rock fragments: 45 to 85 percent.
Organic matter content: 1 or 2 percent.

Bt2 horizon
Hue: 7.5YR or 10YR.
Value: 5 through 7 dry, 4 or 5 moist.
Texture: Very gravelly clay, extremely gravelly clay, extremely gravelly clay loam, or extremely gravelly sandy clay loam.
Clay content: 35 to 50 percent.
Rock fragments: 45 to 85 percent.
Consistence: Very hard or hard dry, friable or very friable moist.

Btq horizon (when present)
Hue: 7.5YR or 10YR.
Value: 5 through 7 dry, 4 or 5 moist.
Texture: Very gravelly sandy clay loam or extremely gravelly sandy clay loam.
Clay content: 25 to 35 percent.
Rock fragments: 45 to 85 percent.
Structure: Subangular blocky but may be massive in some pedons.
Consistence: Very hard or hard dry, friable or very friable moist.

COMPETING SERIES: These are the Floer and Heusser series.

Floer soils are deep to lithic contacts and have secondary carbonates within 100 cm of the soil surface. Heusser soils have abrupt boundaries to the argillic horizon at 50 to 76 cm from the soil surface, have argillic horizons with more than 40 percent clay throughout all subhorizons, and are intermittently moist for 10 to 20 days cumulative between July and October.

GEOGRAPHIC SETTING: Delmo soils are on fan remnants on mountain valleys. These soils formed in alluvium derived from mixed granitic and volcanic rocks. Slopes are 4 to 30 percent. Elevations range from 6,700 to 8,000 feet. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 300 to 380 mm, mean annual temperature is 5 to 5 degrees C, and the frost-free period is 65 to 75 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dooh and Slatter soils. Dooh soils are loamy-skeletal and have thick mollic epipedons. Slatter soils are loamy-skeletal and are very shallow to lithic contacts.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; very high surface runoff; moderately low saturated hydraulic conductivity.

USE AND VEGETATION: Delmo soils are used for rangeland and wildlife habitat. The present vegetation is mainly low sagebrush, Thurber's needlegrass, bluegrass, and prairie junegrass.

DISTRIBUTION AND EXTENT: Western Nevada. These soils are not extensive. MLRA 26.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.

SERIES ESTABLISHED: Douglas County, Nevada, 2012.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 33 cm (A, AB, and Bt1 horizons).
Palexerolls great group feature - The abrupt clay increase of more than 20 percent at 15 cm (between the AB and Bt1 horizons).
Argillic horizon - The zone from 15 to 152 cm (Bt1, Bt2, and Btq horizons).
Particle-size control section - The zone from 15 to 66 cm (Bt1 and Bt2 horizons).

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National Cooperative Soil Survey
U.S.A.