Soil pH in Newport, RI: Lime or Sulfur?

Typical topsoil pH in Newport, RI

Typical topsoil in Newport, RI is pH 5.21, too acidic for vegetable garden. Expect roughly 3.9 lb of lime per 100 sq ft, but only after a soil test confirms it.

What Newport needs, by plant

• Already in range: potatoes, blueberries, azaleas and rhododendrons, blue hydrangeas.
• Lime: lawn (cool-season grass) 3.9 lb/100 sq ft; vegetable garden 3.9 lb/100 sq ft; tomatoes 3.9 lb/100 sq ft; strawberries 2.4 lb/100 sq ft; roses 3.9 lb/100 sq ft; pink hydrangeas 3 lb/100 sq ft.

What to do next

If your test confirms pH near 5.21, spread about 39 lb of ground limestone per 1,000 sq ft of vegetable bed, ideally in fall.

How mixed the soil is

Of the 62,944 surveyed acres in Newport, RI, 87% are strongly acidic (below 5.5), 12% are moderately acidic (5.5-6.5), 2% are near neutral (6.5-7.3). Mapped soils run from pH 4.2 to 8, a spread of 3.8 units across 463 soil components. 87% 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 6.1% clay and 4.78% 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. 0% of mapped components carry free carbonate (lime already in the ground).

Newport against the rest of Rhode Island

pH 5.21 is 0.13 above the Rhode Island median of 5.08. 3 of 5 Rhode Island counties have more acidic topsoil. Nationally it is more acidic than the US county median of 6.05.

Closest in pH within the state: Providence (4.97), Kent (5), Washington (5.08), Bristol (5.21).