Soil Survey of
Dukes County Massachusetts
The following map unit description is from the published "Soil
Survey of Dukes County, Massachusetts"
WhA-Whitman Variant silt loam, 0 to 3 percent slopes. This soil is nearly level, very deep, and very poorly drained. It is in depressions and in low-lying areas adjacent to drainageways. It is in the western part of Martha's Vineyard. The areas of this soil are irregular in shape and range from 5 to 20 acres. They make up less than 1 percent of the survey area.
Typically, the surface layer is very dark grayish brown silt loam about 5 inches thick. The substratum extends to a depth of 60 inches or more. The upper part of the substratum is light brownish gray, mottled sandy loam. The middle part is light brownish gray mottled, sandy clay loam. The lower part is gray, mottled, firm clay loam.
Included with this soil in mapping are small areas of Freetown, Ridgebury Variant, and Swansea soils. Also included are areas of soils where the upper part is loamy sand, sand, and gravelly material. In some areas stones cover 1 to 3 percent of the surface. Included areas make up about 30 percent of this unit.
The permeability of this Whitman Variant soil is moderately rapid or moderate in the upper part of the substratum and slow or very slow in the lower part. Available water capacity is moderate. A seasonal high water table is at or near the surface in fall, winter, and spring and after periods of heavy rainfall.
Most areas of this soil are covered with brush and trees.
The seasonal high water table makes this soil generally unsuitable for cultivated crops. Surface drainage, diversions, or tile drainage or a combination of those practices will help remove water from this soil. Conservation tillage and using crop residue help to maintain tilth and organic matter content in cultivated areas.
The seasonal high water table makes the soil poorly suited to hay and pasture. Drainage and water-tolerant plants are needed. Restriction of grazing when the soil is wet, using proper stocking rates, and rotational grazing are management practices needed to maintain plant densities and desirable species.
This soil is poorly suited to woodland productivity because of the seasonal high water table and a high rate of seedling mortality. Low strength of the soil limits the use of equipment to periods when the soil is dry or frozen. The common trees on this soil are red maple and tupelo.
The seasonal high water table limits the use of this soil as a site for dwellings and septic tank absorption fields. The permeability in the substratum is a further limitation for septic tank absorption fields.
This soil is well suited to use as wetland wildlife habitat. The native plant communities common to this soil provide adequate food and cover.
This soil is in capability subclass Vw.
WmA-Whitman Variant silt loam, 0 to 3 percent slopes, very stony. This soil is nearly level, very deep, and very poorly drained. It is in depressions and in low- lying areas adjacent to drainageways in the western part of Martha's Vineyard. Stones and boulders cover 1 to 3 percent of the surface area. The areas of this soil range from 5 to 40 acres. They make up less than 1 percent of the survey area. The areas are irregular in shape and in many places conform to drainage patterns of the landscape.
Typically, the surface is covered by a 4-inch-thick layer of undecomposed leaves and twigs and well decomposed organic material. The surface layer consists of very dark grayish brown silt loam about 5 inches thick. The substratum extends to a depth of 60 inches or more. It is light brownish gray, mottled sandy clay loam in the upper part and gray, mottled, firm clay loam in the lower part.
Included with this soil in mapping are small areas of Freetown, Ridgebury Variant, and Swansea soils. Also included are areas of soils where the upper part is loamy sand, sand, and gravelly material. In some areas stones and boulders cover 3 to 15 percent of the surface. Included areas make up about 30 percent of this unit.
The permeability of this Whitman Variant soil is moderately rapid or moderate in the upper part of the substratum and slow or very slow in the lower part. Available water capacity is moderate. A seasonal high water table is at or near the surface in fall, winter, and spring and after periods of heavy rainfall.
The seasonal high water table and the stones and boulders on the surface make this soil generally unsuitable for farming.
Most areas are wooded, but the soil is poorly suited to woodland productivity. The seasonal high water table causes a high rate of seedling mortality. Low soil strength limits the use of equipment and restricts use to periods when the soil is dry or frozen. The common trees on this soil are red maple and tupelo.
The seasonal high water table limits the use of this soil as a site for dwellings and septic tank absorption fields. The permeability in the substratum is a further limitation for septic tank absorption fields.
This soil is well suited to use as wetland wildlife habitat. The native plant communities common to this soil provide adequate food and cover.
This soil is in capability subclass VIs.