LOCATION APMAT NV

Established Series
Rev. JBF/WED/JVC
02/2017

APMAT SERIES

The Apmat series consists of very deep, well drained soils that formed in alluvium derived mainly from volcanic rocks. Apmat soils are on fan remnants and stream terraces. Slopes are 2 to 8 percent. The mean annual precipitation is about 640 mm and the mean annual temperature is about 6 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, active, frigid Alfic Argixerolls

TYPICAL PEDON: Apmat very stony coarse sand--forest land. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with 5 percent stones and less than 2.5 cm of pine needle duff.

A1--0 to 13 cm; dark grayish brown (10YR 4/2) very stony coarse sand, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine roots and few medium roots; many very fine through medium tubular pores; 15 percent gravel, 10 percent cobbles, and 10 percent stones; slightly acid (pH 6.4); gradual smooth boundary. (8 to 20 cm thick)

A2--13 to 25 cm; grayish brown (10YR 5/2) gravelly loamy coarse sand, very dark grayish brown (10YR 3/2) moist; moderate fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine roots, and few medium roots; many very fine through medium tubular pores; 15 percent gravel; slightly acid (pH 6.4); clear smooth boundary. (8 to 20 cm thick)

E--25 to 53 cm; light brownish gray (10YR 6/2) very gravelly loamy sand, dark grayish brown (10YR 4/2) moist; massive; soft, very friable, nonsticky and nonplastic; many very fine through coarse roots; many very fine through medium tubular pores; 30 percent gravel and 5 percent cobbles; slightly acid (pH 6.4); clear wavy boundary. (8 to 38 cm thick).

EBt--53 to 84 cm; pale brown (10YR 6/3) and light gray (2.5Y 7/2) very cobble loamy coarse sand, brown (10YR 4/3) and grayish brown (2.5Y 5/2) moist; weak medium angular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine through coarse roots; few very fine and fine tubular pores; few distinct clay films on faces of peds, lining pores, and bridging sand grains; 5 percent gravel, 30 percent cobbles and 5 percent stones, some of which are highly weathered; neutral (pH 6.6); clear irregular boundary. (0 to 50 cm thick)

Bt1--84 to 107 cm; yellowish brown (10YR 5/4) very stony coarse sandy loam, dark yellowish brown (10YR 4/4) moist, with a few seams of grayish brown (2.5Y 5/2); massive; slightly hard, friable, moderately sticky and slightly plastic; very few roots; very few pores; common distinct clay films lining pores and bridging sand grains; 10 percent cobbles and 40 percent stones, some highly weathered; neutral (pH 6.6); clear irregular boundary. (15 to 50 cm thick).

Bt2--107 to 140 cm; grayish brown (10YR 5/2) extremely stony coarse sandy loam, dark yellowish brown (10YR 4/4) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; very few roots; very few pores; few faint clay bridges between sand grains; 5 percent gravel, 10 percent cobbles, and 50 percent stones; some fragments are highly weathered; neutral (pH 6.6); clear irregular boundary. (20 to 70 cm thick)

C--140 to 160 cm; pale brown (10YR 6/3) extremely bouldery loamy coarse sand, brown (10YR 4/3) moist; massive; soft, very friable, nonsticky and nonplastic; 60 percent boulders and stones, 20 percent cobbles, all highly weathered; moderately acid (pH 6.0).

TYPE LOCATION: Washoe County, Nevada; approximately 2,600 feet east and 2,400 feet north of the southwest corner of section 10, T. 17 N., R. 19 E.; USGS Washoe City 7.5 minute topographic quadrangle; latitude 39 degrees 21 minutes 10 seconds N and longitude 119 degrees 50 minutes 9 seconds W; WGS84 Decimal Degrees 39.3527778 latitude, -119.8358333 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Dry between depths of 20 to 75 cm from mid-July through mid-October and moist in some parts the rest of the time in normal years; xeric moisture regime.
Mean annual soil temperature: 7 to 8 degrees C.
Mollic epipedon thickness: 25 to 40 cm.
Depth to base of argillic horizon: 75 to 150 cm.
Reaction: Moderately acid through neutral.
Base saturation: 50 to 75 percent by sum of cations.

A1 and A2 horizons
Hue: 10YR or 7.5YR.
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3, dry or moist.

E horizon
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 2 or 3, dry or moist.

Bt1 and Bt2 horizons
Hue: 10YR or 7.5YR.
Value: 5 or 6 dry, 4 or 5 moist.
Chroma: 3 or 4, dry or moist.
Texture: Coarse sandy loam, sandy loam, or loam.
Clay content: 10 to 18 percent.
Rock fragments: 35 to 70 percent.

COMPETING SERIES: There are currently no other series in this family.

GEOGRAPHIC SETTING: Apmat soils are on fan remnants and stream terraces. They formed in alluvium derived mainly from volcanic rocks. The alluvium is mainly reworked till. Slopes are 2 to 8 percent. Elevations range from 1,650 to 2,290 meters. The climate is cool continental. The mean annual precipitation ranges from 500 to 850 mm. The mean annual temperature is 5 to 7 degrees C. The frost-free period is 50 to 80 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Fraval, Jumbo, and Oest soils. Fraval and Jumbo are less than 150 cm deep. Oest soils average l8 to 27 percent clay in the particle-size control section and are mesic.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; moderately rapid permeability; high saturated hydraulic conductivity.

USE AND VEGETATION: Apmat soils are used for forest land, recreation, and residential development. The vegetation is a forest canopy of Jeffrey pine and ponderosa pine with an understory of mountain big sagebrush, antelope bitterbrush, and Thurber's needlegrass.

DISTRIBUTION AND EXTENT: Western Nevada. These soils are not extensive with about 2,400 acres of the series mapped to date. MLRA 26.

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

SERIES ESTABLISHED: Washoe County, Nevada, South Part, 1980.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 25 cm (A1 and A2 horizons).
Albic horizon - The zone from 25 to 53 cm (E horizon).
Alfic subgroup feature - The zone from 25 to 84 cm (E and E/Bt horizons).
Argillic horizon - The zone from 84 to 140 cm (Bt1 and Bt2 horizons).
Particle-size control section - The zone from 84 to 134 cm (Bt1 horizon and part of the Bt2 horizon).

The revision of April 2008 updated the taxonomic class from Loamy-skeletal, mixed, superactive, frigid Ultic Argixerolls based on recognition of an albic horizon and change in the cation exchange activity class because of laboratory data.

ADDITIONAL DATA: The typical pedon at the series type location has full characterization data by the Soil Survey Laboratory (SSL) as pedon ID 75NV031008 (pedon # 40A3422).

National Cooperative Soil Survey
U.S.A.