Soil pH in Northampton, NC: Lime or Sulfur?

Typical topsoil pH in Northampton, NC

Typical topsoil in Northampton, NC is pH 4.96, too acidic for vegetable garden. Expect roughly 10.5 lb of lime per 100 sq ft, but only after a soil test confirms it.

What Northampton needs, by plant

• Already in range: blueberries, azaleas and rhododendrons.
• Just outside, test first: potatoes (off by 0), blue hydrangeas (off by 0).
• Lime: lawn (cool-season grass) 10.5 lb/100 sq ft over 3 applications; vegetable garden 10.5 lb/100 sq ft over 3 applications; tomatoes 10.5 lb/100 sq ft over 3 applications; strawberries 7 lb/100 sq ft over 2 applications; roses 10.5 lb/100 sq ft over 3 applications; pink hydrangeas 9.1 lb/100 sq ft over 2 applications.

What to do next

If your test confirms pH near 4.96, spread about 105 lb of ground limestone per 1,000 sq ft of vegetable bed in 3 doses, ideally in fall.

How mixed the soil is

Of the 309,025 surveyed acres in Northampton, NC, 86% are strongly acidic (below 5.5), 14% are moderately acidic (5.5-6.5). Mapped soils run from pH 4.5 to 6.4, a spread of 1.9 units across 110 soil components. 86% 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 14.1% clay and 2.02% organic matter, which this site treats as loam. Moving it one pH unit takes about 7 lb of lime or 2.3 lb of sulfur per 100 sq ft. None of the mapped components carry free carbonate.

Northampton against the rest of North Carolina

pH 4.96 is 0.2 below the North Carolina median of 5.16. 22 of 100 North Carolina counties have more acidic topsoil. Nationally it is more acidic than the US county median of 6.05.

Closest in pH within the state: Perquimans (4.95), Tyrrell (4.95), Beaufort (4.96), Columbus (4.96), Sampson (4.96), Wayne (4.96), Madison (5), Brunswick (5.01).

The range in North Carolina runs from Swain at 4.56 to Davie at 5.9; Northampton sits 30% of the way up.