LOCATION SIWANOY NY

Established Series
RKS
01/2014

SIWANOY SERIES

The Siwanoy series consists of very deep, poorly drained soils formed in a mantle of local slopewash over friable till, aeolian, or glaciolacustrine deposits. They are found in low areas on glaciated uplands. Saturated hydraulic conductivity is moderately low through high. Slopes range from 0 to 8 percent. Mean annual temperature is about 13 degrees C and mean annual precipitation is about 1196 mm.

TAXONOMIC CLASS: Coarse-silty, mixed, active, nonacid, mesic Typic Humaquepts

TYPICAL PEDON: Siwanoy silt loam in a nearly level woodland. (Colors are for moist soil unless otherwise stated.)

A1---0 to 9 cm; very dark brown (10YR 2/2) silt loam, gray (10YR 5/1) dry; moderate coarse granular and moderate medium granular structure; friable; common fine roots and common medium roots; strongly acid (pH 5.2); clear smooth boundary.

A2--9 to 22 cm; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; moderate coarse granular structure; friable; common fine roots, common medium roots and common coarse roots; strongly acid (pH 5.4); clear wavy boundary. (Combined thickness of the A horizons is 18 to 25 cm.)

Bg1--22 to 46 cm; gray (2.5Y 5/1) silt loam; moderate coarse subangular blocky structure; friable; very few fine roots and common medium roots; 25 percent (many) medium prominent strong brown (7.5YR 5/8) masses of oxidized iron and 15 percent (common) medium faint gray (2.5Y 6/1) iron depletions; 15 percent (common) coarse cylindrical very dark gray (10YR 3/1) worm casts on surfaces along pores; strongly acid (pH 5.5); clear smooth boundary.

Bg2--46 to 69 cm; gray (5Y 6/1) silt loam; moderate coarse subangular blocky structure; friable; very few fine roots and moderately few medium roots; 15 percent (common) medium prominent strong brown (7.5YR 4/6) masses of oxidized iron; 7 percent (common) fine cylindrical dark gray (10YR 4/1) worm casts on surfaces along pores; moderately acid (pH 5.6); 10 percent pockets of brown (7.5YR 4/4) saprolitic material; clear smooth boundary. (Combined thickness of the Bg horizons is 28 to 47 cm.)

BCg--69 to 80 cm; gray (5Y 5/1) silt loam; weak very coarse subangular blocky structure; friable; very few fine roots; 7 percent (common) medium prominent brown (7.5YR 4/4) masses of oxidized iron; moderately acid (pH 5.8); 10 percent pockets of brown (7.5YR 4/4) saprolitic material; clear smooth boundary. (11 to 48 cm thick).

Cg--80 to 109 cm; olive gray (5Y 5/2) very fine sandy loam; 10 percent clay; massive; friable; 7 percent (common) medium prominent yellowish brown (10YR 5/4) masses of oxidized iron; moderately acid (pH 6.0). (29 to 43 cm thick.)

2C--109 to 153 cm; brown (10YR 4/3) loamy sand with pockets of gray (5Y 5/1) silt loam; massive; friable; 10 percent gravel; slightly acid (pH 6.2).

TYPE LOCATION: Bronx County, New York: Pelham Bay Park, 1130 feet due Northwest from Glover's Rock, between Orchard Beach Road and Bartow Creek. USGS Flushing, NY, topographic quadrangle: Latitude 40 degrees 52 minutes, 2.10 seconds N. and Longitude 73 degrees, 48 minutes, 22.30 seconds W. WGS 1984.

RANGE IN CHARACTERISTICS: Thickness of the solum ranges from 46 to 100 cm. Depth to bedrock is commonly more than 183 cm. Rock fragments, mainly gravel and cobbles, range from 0 to 5 percent above 100 cm and from 0 to 60 percent below 100 cm. Stones cover 0 to 3 percent of the surface in some areas.

The A horizon has hue of 10YR to 2.5Y, value of 2 or 3, and chroma of 1 or 2. Texture is commonly silt loam, very fine sandy loam, or loam. Structure is granular or subangular blocky with very friable or friable consistence. Reaction ranges from very strongly acid to slightly acid.

The B horizons have hue of 7.5YR to 5Y, value of 4 to 6, and chroma of 1 or 2. Distinct or prominent redoximorphic features are present. Textures include silt loam, silty clay loam, loam, clay loam, and very fine sandy loam. Structure is commonly subangular blocky with friable consistence. Reaction ranges from very strongly acid to slightly acid.

BC horizons, where present, are similar in color and textures to B horizons. Fine sandy loam may be present at depth. Structure is commonly weak subangular blocky with friable consistence. Reaction ranges from very strongly acid to slightly acid.

The C horizons have hue of 10YR to 5Y, value 4 to 7, and chroma of 1 to 4. Textures include silt loam, silty clay loam, loam, clay loam, very fine sandy loam, fine sandy loam. Sandy loam and loamy sand may be found below the control section. Structure is commonly massive with friable consistence. Reaction ranges from very strongly acid to neutral.

The 2C horizons (which, if present, occur below the particle size control section) have hue of 10YR to 5Y, value 4 to 7, and chroma of 1 to 4. Textures include sandy loam, loamy sand, with pockets or thin lenses of silt loam. Structure is massive or massive with plate-like divisions. Consistence is friable or firm. Reaction ranges from very strongly acid to neutral.

COMPETING SERIES: The Birdsall series is currently the only other series in the same family. Birdsall soils are very poorly drained.

GEOGRAPHIC SETTING: Siwanoy soils are nearly level to gently sloping soils found in depressional areas and drainageways in till plains. These soils formed in acid slope wash derived from glacial till, aeolian, or glaciolacustrine deposits. Mean annual precipitation ranges from 1021 to 1325 mm. Mean annual temperature ranges from 8 to 17 degrees C.

GEOGRAPHICALLY ASSOCIATED SOILS: These include the Charlton, Sutton, Leicester, Chatfield, Hollis, Paxton Woodbridge, Ridgebury, and Whitman soils. The well drained Charlton, the moderately well drained Sutton, and the poorly drained Leicester soils, associated in a drainage sequence, are formed in similar materials. Chatfield and Hollis soils have bedrock at 50 to 100 and 25 to 50 cm depths, respectively. The well drained Paxton, moderately well drained Woodbridge, poorly drained Ridgebury, and the very poorly drained Whitman soils, associated in a drainage sequence, are formed in similar materials but all have a dense substratum.

DRAINAGE AND PERMEABILITY: Poorly drained. The potential for surface runoff is low. Saturated hydraulic conductivity is moderately low to high.

USE AND VEGETATION: Most areas are wooded. Common trees include red maple, sweetgum, swamp white oak.

DISTRIBUTION AND EXTENT: Low-lying areas in glaciated uplands in southeastern New York and possibly New Jersey, MLRAs 144A and 149B. The series is not extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Amherst, Massachusetts

SERIES ESTABLISHED: Bronx County, New York, 2014. Series proposed in Bronx County, New York, 2009. The name refers to an Indian tribe that once frequented the Pelham Bay area.

REMARKS: Siwanoy soils are mapped in the initial survey areas of Bronx County, NY. The soils are of minimal extent (less than 200 acres), however they are of unique importance to users of the soil surveys.

Siwanoy soils often exhibit an irregular decrease in organic carbon with depth however this is a result of anthropogenic filling (deposition) not alluvial deposition; excluding them from the concept of Fluvaquentic Humaquepts. Proposed revisions to soil taxonomy in ICOMANTH Circular Letter 7 developed for anthropogenic soils will help to clarify this difference.

Diagnostic horizons and features recognized in this pedon include:
1. Umbric epipedon - the zone from 0 to 22 cm (A1 and A2 horizons).
2. Cambic horizon - the zone from 22 to 80 cm.
3. Aquic conditions - the zone from 22 to 69 cm (Bg1 and Bg2 horizons).

National Cooperative Soil Survey
U.S.A.