The following is a map unit description from the "Soil Survey of Norfolk and Suffolk Counties, Massachusetts (Peragallo, 1989)"
NpB-Newport silt loam, 3 to 8 percent slopes. This is a very deep, gently sloping, well drained soil on top of hills in the Boston Basin and along the Plymouth County line. Areas are oval and range from 6 to 30 acres in size.
Typically, the surface layer is dark brown silt loam about 9 inches thick. The subsoil is light olive brown silt loam about 17 inches thick. The substratum is firm, light yellowish brown silt loam to a depth of 60 inches or more. In many areas the coarse fragments in the soil are 50 to 75 percent, by volume, flat, dark gray shale and slate and are 1 to 15 inches long.
Included with this soil in mapping are small areas of Paxton soils in positions on the landscape similar to those of the Newport soil. Also included are small areas of Pittstown soils in low, flat areas or depressions. Also included are small areas of Udorthents, loamy, where the Newport soil has been cut away or covered with more than 20 inches of loamy fill material. Also included are a few small areas of Urban land. Included soils and areas of Urban land make up about 10 percent of this map unit.
Permeability: Moderate in the surface layer and the subsoil and slow 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: 1.5 to 2.5 feet.
Hydrologic group: C.
Most areas of this soil are used for parks and playgrounds. Some areas are used as sites for buildings.
This soil is very well suited to cultivated crops, hay, and pasture and to use as orchards. Erosion is a hazard and is the main management concern. Contour tillage, stripcropping, cover crops, and grasses and legumes in the cropping system help to reduce runoff and to control erosion.
Potential productivity for northern red oak on this soil is moderately high. The soil is easily managed for woodland. The high productivity of the soil justifies intensive management for either hardwoods or conifers. Plant competition at regeneration is moderate if conifers are grown. Thinning crowded stands to accepted standard stocking levels allows more vigorous growth. 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. Pruning helps to improve the quality of white pine.
Constructing buildings with the lower or basement level above the seasonal high water table helps to prevent the damage to the interior by the seasonal high water table. Constructing roads on well compacted, coarse textured base material and providing adequate side ditches and culverts help to prevent the damage to the pavement by the seasonal high water table and frost action. If the soil is used as sites for septic tank absorption fields slow permeability restricts it from readily absorbing the effluent. Installing a drain field larger than average helps to overcome this limitation. Where suitable outlets are available, curtain drains around the absorption field help to lower the seasonal high water table.
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