Soil pH in Plymouth, MA: Lime or Sulfur?

Typical topsoil pH in Plymouth, MA

Typical topsoil in Plymouth, MA is pH 4.79, too acidic for vegetable garden. Expect roughly 5.1 lb of lime per 100 sq ft, but only after a soil test confirms it.

What Plymouth needs, by plant

• Already in range: blueberries, azaleas and rhododendrons.
• Just outside, test first: potatoes (off by 0.2), blue hydrangeas (off by 0.2).
• Lime: lawn (cool-season grass) 5.1 lb/100 sq ft over 2 applications; vegetable garden 5.1 lb/100 sq ft over 2 applications; tomatoes 5.1 lb/100 sq ft over 2 applications; strawberries 3.6 lb/100 sq ft; roses 5.1 lb/100 sq ft over 2 applications; pink hydrangeas 4.5 lb/100 sq ft.

What to do next

If your test confirms pH near 4.79, spread about 51 lb of ground limestone per 1,000 sq ft of vegetable bed in 2 doses, ideally in fall.

How mixed the soil is

Of the 375,592 surveyed acres in Plymouth, MA, 84% are strongly acidic (below 5.5), 15% are moderately acidic (5.5-6.5), 1% are near neutral (6.5-7.3). Mapped soils run from pH 3.8 to 7.4, a spread of 3.6 units across 960 soil components. 84% of the land falls in one class, so the county figure is a fair first guess for most yards here.

Clay, organic matter and rates

Topsoil here averages 3.9% clay and 4.34% organic matter, which this site treats as sandy. Moving it one pH unit takes about 3 lb of lime or 1.2 lb of sulfur per 100 sq ft. None of the mapped components carry free carbonate.

Plymouth against the rest of Massachusetts

pH 4.79 is 0.23 below the Massachusetts median of 5.02. 3 of 14 Massachusetts counties have more acidic topsoil. Nationally it is more acidic than the US county median of 6.05.

Closest in pH within the state: Nantucket (4.64), Dukes (4.66), Barnstable (4.67), Franklin (5), Hampden (5.02), Norfolk (5.02), Suffolk (5.02).

The range in Massachusetts runs from Nantucket at 4.64 to Hampshire at 5.28; Plymouth sits 23% of the way up.