LOCATION APMAT NVEstablished Series
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 1 inch of pine needle duff.
A1--0 to 5 inches; 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. (3 to 8 inches thick).
A2--5 to 10 inches; 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. (3 to 8 inches thick).
E--10 to 21 inches; 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. (3 to 15 inches thick).
E/Bt--21 to 33 inches; 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, firm, 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; 5 percent stones, some of which are highly weathered; neutral (pH 6.6); clear irregular boundary. (0 to 20 inches thick).
Bt1--33 to 42 inches; 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, firm, 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. (6 to 20 inches thick).
Bt2--42 to 55 inches; grayish brown (10YR 5/2) extremely stony coarse sandy loam, dark yellowish brown (10YR 4/4) moist; massive; slightly hard, firm, slightly sticky and slightly plastic; very few roots; very few pores; few thin clay films bridging sand grains; 5 percent gravel, 10 percent cobbles, and 50 percent stones; some fragments are highly weathered; neutral (pH 6.6); clear irregular boundary. (8 to 28 inches thick).
C--55 to 63 inches; pale brown (10YR 6/3) extremely bouldery loamy coarse sand, brown (10YR 4/3) moist; massive; soft, 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 9.68 seconds N. and longitude 119 degrees 50 minutes 8.68 seconds W., NAD83.
RANGE IN CHARACTERISTICS:
Soil moisture - The soil is dry between depths of 8 to 30 inches 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 - 44 to 47 degrees F.
Mollic epipedon thickness - 10 to 16 inches.
Depth to base of argillic horizon - 30 to 60 inches.
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 5,400 to 7,500 feet. The climate is cool continental. The mean annual precipitation ranges from 20 to 35 inches. The mean annual temperature is 41 to 44 degrees F., mean January temperature is about 26 degrees F., and mean July temperature is about 61 degrees F. 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 60 inches deep. Oest soils average l8 to 27 percent clay in the control section and are mesic.
DRAINAGE AND PERMEABILITY: 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 OFFICE RESPONSIBLE: Reno, Nevada.
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 10 inches (A1 and A2 horizons).
Albic horizon - The zone from 10 to 21 inches (E horizon).
Alfic subgroup feature - The zone from 10 to 33 inches (E and E/Bt horizons).
Argillic horizon - The zone from 33 to 55 inches (Bt1 and Bt2 horizons).
Particle-size control section - The zone from 33 to 53 inches (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.
The superactive cation exchange activity class was added in 03/2003 to the taxonomic classification by the National Soil Survey Center on request of the Reno MLRA office, without review of the soil series property 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).