LOCATION EWA HI

Established Series
Rev. CWS/SN/HI/JVP/MK
07/2019

EWA SERIES

The Ewa series consists of deep, well drained soils that formed in alluvium weathered from basaltic rock. Ewa soils are on alluvial fans and terraces and have slopes of 0 to 12 percent. The mean annual precipitation is about 684 millimeters (27 inches), and the mean annual air temperature is about 23 degrees C. (73 degrees F.).

TAXONOMIC CLASS: Fine, kaolinitic, isohyperthermic Aridic Haplustolls

TYPICAL PEDON: Ewa silty clay loam--irrigated sugarcane. (Colors are for moist soil unless otherwise noted.)

Ap1--0 to 33 centimeters (0 to 13 inches); dark reddish brown (5YR 3/2) silty clay loam, dark reddish brown (5YR 3/3) dry; weak, fine and very fine granular structure; hard, friable, moderately sticky and moderately plastic; many fine roots; many fine and very fine pores; common worm holes and casts; many fine black (10YR 2/1) concretions; strong effervescence with hydrogen peroxide; neutral (pH 7.0); clear wavy boundary. (11 to 13 inches thick)

Ap2--33 to 46 centimeters (13 to 18 inches); dark reddish brown (2.5YR 3/3) silty clay loam, dark reddish brown (2.5YR 3/4) dry; weak fine and very fine granular structure; hard, friable, moderately sticky and moderately plastic; many fine roots; common very fine tubular and interstitial pores; many very fine black concretions; strong effervescence with hydrogen peroxide; neutral (pH 7.0); clear wavy boundary. (3 to 6 inches thick)

Bw1--46 to 114 centimeters (18 to 45 inches); dark reddish brown (2.5YR 3/4) silty clay loam, dark red (2.5YR 3/6) dry; weak fine and very fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many fine roots; many fine , very fine, andcommon medium and few coarse tubular pores; weak patchy pressure faces on peds; few reddish yellow (7.5YR 6/6) and yellow (10YR 7/6) sand grains; common very fine black (10YR 2/1) concretions; strong effervescence with hydrogen peroxide; neutral (pH 7.0); diffuse wavy boundary. (25 to 28 inches thick)

Bw2--114 to 152 centimeters (45 to 60 inches); dark red (2.5YR 2.5/5) silty clay loam, dark red (2.5YR 3/6) dry; moderate medium and fine subangular blocky structure; hard, friable, slightly sticky and moderately plastic; many fine roots; many fine , very fine pores, and medium and few medium tubular pores; many thin coatings that are patchy in upper part, nearly continuous in lower part; many sand grains like those in Bw1 horizon;; strong effervescence with hydrogen peroxide; neutral (pH 7.2).

TYPE LOCATION: Island of Oahu, Honolulu County, Hawaii; Ewa Sugar Plantation, west through Waipahu on Kamehameha Highway to Kunia Road junction, west on Kam Highway 1.8 miles, then 0.3 mile north on plantation road, proceed then west 800 feet along upper canal road, 200 feet south of road. Latitude 21 degrees 22 minutes 20 seconds north and longitude 158 degrees 3 minutes 33 seconds west (old Hawaiian datum).

RANGE IN CHARACTERISTICS: Depth to coral limestone or gravelly alluvium ranges from 127 to 152 centimeter (50 to 60 inches).

The A horizon has hue of 5YR or 2.5YR, value of 2.5 or 3 moist or 3 dry, and chroma of 2 through 5 moist or dry. It is silty clay loam or stony silty clay. It has weak, fine and very fine granular structure and is very friable or friable. It ranges from pH 6.8 to 7.0.

The B horizon has hue of 5YR or 2.5YR, value of 2.5 or 3 moist or 3 dry, and chroma of 4 through 5 moist or dry. It is silty clay loam or silty clay. It has weak or moderate fine, very fine or medium subangular blocky structure. It ranges from pH 7.0 to 7.2.

COMPETING SERIES:
There are no competing series.

GEOGRAPHIC SETTING: Ewa soils are on alluvial fans and terraces at elevations ranging from sea level to 111 meters (0 to 365 feet). Slope is 0 to 12 percent. The soils formed in alluvium which washed from the adjacent mountain slopes and is material weathered from basic igneous rocks. The mean annual precipitation (MAP) ranges from 422 to 975 millimeters ( 17 to 38 inches). Average January temperature is 22 degrees C. (71 degrees F.), average July temperature is 26 degrees C. (78 degrees F.), and the mean annual air temperature (MAAT) is about 23 degrees C. (73 degrees F.).

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Honouliuli, Mamala, Molokai, and Wahikuli soils. Honouliuli soils have clay texture throughout. Mamala soils are less 51 centimeters (20 inches) deep to the coral limestone and effervesce with hydrochloric acid throughout. Molokai soils have prismatic structure in the upper part of the B horizon. Wahikuli soils are 102 centimeters (40 inches) or less to basaltic bedrock.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
The soils are well drained. Runoff is slow to medium. Saturated hydraulic conductivity is moderately high.

USE AND VEGETATION: These soils are used for irrigated sugarcane and pasture. Natural vegetation is kiawe (Prosopis chilensis), koa haole (Leucaena glauca), klu (Acacia farnesiana), fingergrass (Chloris sp.), and bristly foxtail (Setaria verticillata).

DISTRIBUTION AND EXTENT: Island of Oahu and Maui, Hawaii. These soils are moderately extensive. Total of approximately 12,506 acres.

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

SERIES ESTABLISHED: Island of Oahu, Honolulu County, Hawaii, 1955.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from a depth of 0 to 46 cm (Ap1 and Ap2).
Cambic Horizon - the zone from a depth of 46 to 152 cm (Bw1 and Bw2).

FCC Classification: Cdk.

Edit Log: 5/19 MRK. Competing series updated and minor edits.
12/03 SN. Horizon designations updated; added depth range.
8/00 SN. Classification changed from Fine, kaolinitic, isohyperthermic Torroxic Haplustolls due to changes in Taxonomy.

ADDITIONAL DATA: Ewa NSSL sample S63HI-003-001.

National Cooperative Soil Survey
U.S.A.