LOCATION PISHAGQUA RITentative Series
The Pishagqua series consists of very deep, subaquic soils that are permanently submerged in low energy depositional basins, estuaries and coastal lagoons. The Pishagqua soils formed in silty estuarine deposits. Estimated saturated hydraulic conductivity is moderately high to high. Slopes range from 0 to 3 percent, mean annual air temperature is 10 degrees C, and mean annual precipitation is 1320 mm.
TAXONOMIC CLASS: Fine-silty, mixed, superactive, nonacid, mesic Typic Sulfaquents
TYPICAL PEDON: Pishagqua silt loam on a south facing 1 percent, concave slope in an Eelgrass (Zostera marina) bed of a lagoon bottom channel under 2 meters (National Vertical Datum 1988) of estuarine water. Tidal range is 24 cm. (Colors are for moist soil unless otherwise noted).
Ag--0 to 15 cm; black (5Y 2.5/2), silt loam, gray (5Y 6/1) dry; massive; loose, nonsticky, nonplastic, very fluid; 1 percent flat angular shell fragments; hydrogen sulfide odor; strongly saline; slightly alkaline (pH 7.5); extremely acid (pH 3.9) after 8 weeks of aerobic incubation; clear boundary. (0 to 38 cm thick).
Cg1--15 to 110 cm; black (5Y 2.5/1) silt loam; gray (5Y 5/1) dry; massive; loose, nonsticky, nonplastic, very fluid; 1 percent flat angular fine and medium shell fragments; hydrogen sulfide odor; strongly saline ;neutral (pH 7.0); extremely acid (pH 3.7) after 8 weeks of aerobic incubation; gradual boundary.
Cg2--110 to 160 cm; black (5Y 2.5/1) silt loam, gray (5Y 6/1) dry; massive; loose, nonsticky, nonplastic, moderately fluid; hydrogen sulfide odor; neutral (pH 6.8); strongly saline; ultra acid (pH 3.3) after 8 weeks of aerobic incubation; gradual boundary.
Cg3--160 to 200 cm; black (5Y 2.5/1) silt loam, gray (5Y 6/1) dry; massive; loose, nonsticky, nonplastic, moderately fluid; 1 percent flat subangular shell fragments; hydrogen sulfide odor; moderately saline; neutral (pH 6.7); ultra acid (pH 3.4) after 8 weeks of aerobic incubation; .
TYPE LOCATION: Washington County, Rhode Island; Town of Charlestown, Fort Neck Cove of Ninigret Pond, about 1,360 feet north of the western tip of Potato Point and 1,260 feet south-west of the eastern-most shoreline position of Tautog Cove, Carolina USGS Quadrangle; lat. 41 degrees 22 minutes 33.77 seconds N. and long. 71 degrees 38 minutes 48.47 seconds W. NAD 83.
RANGE IN CHARACTERISTICS:
The soils are permanently submerged. Initial reaction is neutral to slightly alkaline and extremely to ultra acid after 8 weeks of aerobic incubation. The soil is typically strongly saline in the upper part and moderately to strongly saline in the lower part. The thickness of silty estuarine material is 100 cm or more. Shell fragments range from 0 to 15 percent. Shell fragment types typically include soft shell clam, quahog, oyster, periwinkle, and razor clam. Commonly, algal and plant fragments are throughout the profiles. It is massive throughout.
The Ag horizon, where present, has hue of 2.5Y to 5Y moist or dry, value of 2.5 to 3 moist, 5 to 7 dry and chroma 2 or less moist or dry. Textures range from silt loam to silty clay loam with mucky analogs in some pedons. Consistence is moderately to very fluid wet, very friable to loose moist, soft dry, and non-sticky to slightly sticky and plastic. Sulphurous odor is present.
Cg layers have hue of 5Y to N moist or dry, value 2.5 to 4 moist, 5 to 7 dry and chroma 2 or less moist or dry. Textures of the Cg layers include very fine sandy loam, silt loam and silty clay loam with mucky analogs in some pedons. Some pedons have thin strata of sandy material. Consistence is slightly to very fluid wet, very friable to loose moist, soft dry, and non-sticky to slightly sticky and plastic. Sulphurous odor is present.
Some pedons are underlain at a depth greater than 100 cm by buried organic deposits, sandy estuarine material, loess, and/or glaciofluvial sand and gravel.
COMPETING SERIES: There are no competing series. The Appoquinimink, Boxiron, Broadkill, and Southpoint soils are in related families. Appoquinimink, Boxiron and Broadkill soils are flooded twice daily by tidal water. Appoquinimink and the subaqueous Southpoint soils are underlain by organic horizons within a depth of 100 cm. Boxiron soils have a histic epipedon. Broadkill soils have a ratio of cation exchange activity to clay of 0.40 to 0.60 within the cation exchange activity control section.
GEOGRAPHIC SETTING:
The Pishagqua soils are permanently submerged with salt or brackish water in low energy (little affected by wave energy, deposition of sandy material, or storm events) basins and channels of coastal lagoons. The soils formed in silty estuarine sediments in water depths of 1 to 5 meters. Most areas have slope less than 3 percent and are slightly concave to nearly level. The mean annual air temperature is 10 degrees C, and mean annual precipitation is 1320 mm.
GEOGRAPHICALLY ASSOCIATED SOILS:
These are the
Matunuck, Pawcutuck, Quanaduck(T) and Wamphassuc(T) soils. Matunuck and Pawcutuck soils are on tidal marshes. Wamphassuc soils have coarser textures and occur in submerged valleys and terraces in bays. Quanaduck soils are underlain by coarse textured material within 100 cm of the soil surface.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Subaqueous soil, peraquic soil moisture regime, moderately high to high saturated hydraulic conductivity. The soil is permanently submerged with salt or brackish water. Runoff is negligible.
USE AND VEGETATION:
Uses include shell fishing, marinas, moorings and aquaculture. Benthic fauna such as tubeworms, clams, juvenile blue crabs, scallops and juvenile finfish are associated with this soil. Native vegetation includes eelgrass (Zostera marina) and widgeon grass (Ruppia maritima). Many areas have a mat of floating macroalgae at the soil/water interface. Vegetative cover ranges from 0 to 100 percent.
DISTRIBUTION AND EXTENT: Rhode Island, U.S.A.; MLRA 144A. This series is of small extent.
MLRA OFFICE RESPONSIBLE: Amherst, Massachusetts
SERIES PROPOSED: Washington County, Rhode Island, 2007.
REMARKS: Series name was taken from Algonquian word for mud and/or dirt. Pishagqua soils were formerly included in mapping with miscellaneous areas of water.
Upon drying and exposure to air common, fine and medium 5Y 5/4 mottles appeared throughout some pedons.
Horizon boundary is not included due to the method of sampling (core).
Applying the proposed Wassents suborder, this soil classifies as a Fine-silty, mixed, superactive, nonacid, mesic Typic Sulfiwassent.
Diagnostic horizons and other diagnostic soil characteristics recognized in this pedon are:
1. Ochric epipedonthe zone from the surface to a depth of 15 cm (Ag horizon).
2. Aquic conditions--the soil is permanantly submerged, the zone from 0 to 200 cm has positive soil water potential. When described, all layers reacted positively to alpha-alpha' dipyridyl.
3. Sulfidic feature--The zone from 0 cm to 100 cm contains sulfidic materials in all horizons (verified by moist incubation).
4. High n-valuethe zone from the surface to 100 cm has an n-value greater than 0.7
ADDITIONAL DATA:
This pedon was sampled as S04-RI009-001 by the University of Rhode Island. Support pedons used to develop this series description include S05-RI-009-004 (sampled by the NSSL), S04-RI-009-002 (Sampled by the University of Rhode Island), S05-RI-009-013B, S05-RI-009-005 (sampled by the NSSL), and 00NP056 (sampled by University of Rhode Island for graduate thesis).