The following is a map unit description from the "Soil Survey of Norfolk and Suffolk Counties, Massachusetts (Peragallo, 1989)"
MmA-Merrimac fine sandy loam, 0 to 3 percent slopes. This is a very deep, nearly level, somewhat excessively drained soil in broad areas on plains and terraces that commonly follow major stream valleys. Areas are irregular or rounded in shape and range from 6 to 60 acres.
Typically, the surface layer is dark brown fine sandy loam about 9 inches thick. The subsoil is about 14 inches thick. It is yellowish brown fine sandy loam in the upper part and yellowish brown loamy sand in the lower part. The substratum is light yellowish brown, stratified very gravelly coarse sand to a depth of 60 inches or more. In places the texture changes abruptly from fine sandy loam or loamy sand in the subsoil to very gravelly coarse sand in the substratum. In areas of this soil in the Boston Basin and in Weymouth, the subsoil and the substratum are mostly olive colored and are 50 to 75 percent, by volume, coarse fragments of dark, flat shale and slate.
Included with this soil in mapping are a few small areas of Hinckley soils on knolls and Sudbury soils in low areas. Also included are areas where the surface layer has been removed or disturbed. Included areas make up about 10 percent of this map unit.
Soil properties:Permeability: Moderate or moderately rapid in the
surface layer and the subsoil and rapid or very rapid in the
substratum.
Available water capacity: Moderate.
Soil reaction: Very strongly acid to moderately acid
throughout.
Depth to bedrock: More than 60 inches.
Depth to the seasonal high water table: More than 6
feet.
Hydrologic group: A.
Most areas of this soil are used as individual homesites, as sites for commercial and industrial buildings, and as parking lots. Some areas are farmed, and some are woodland.
This soil is very well suited to farming, lawns, landscaping, and gardens. Because of droughtiness, however, irrigation is needed for best plant growth. Mixing crop residue and manure into the surface layer increases the water-holding capacity.
Potential productivity for northern red oak on this soil is moderate. Seedling mortality is moderate because of moisture stress caused by droughtiness. Minimizing soil disturbance, retaining the sponge-like mulch of leaves, and designing regeneration cuts to optimize shade and reduce evapotranspiration help to retain the limited soil moisture. Thinning crowded stands to accepted standard stocking levels allows more vigorous growth. In thinning operations it is important to remove diseased, poorly formed, and otherwise undesirable trees. Shelterwood cutting, seed-tree cutting, and clearcutting help to establish natural regeneration or to provide suitable planting sites. Removing or controlling competing vegetation allows best growth of newly established seedlings. Softwood trees generally grow faster on this soil than hardwood trees.
This soil has no major limitations for building site development and for local roads and streets. If the soil is used as sites for septic tank absorption fields, ground water pollution is a hazard. Because of rapid or very rapid permeability, the soil readily absorbs but does not adequately filter the effluent. Low density housing development reduces the volume of effluent, thus lessening the pollution hazard.
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