Soil pH in Wake, NC: Lime or Sulfur?

Typical topsoil pH in Wake, NC

Typical topsoil in Wake, NC is pH 5.56, too acidic for vegetable garden. Expect roughly 6.3 lb of lime per 100 sq ft, but only after a soil test confirms it.

What Wake needs, by plant

• Already in range: potatoes, strawberries, azaleas and rhododendrons.
• Just outside, test first: blueberries (off by 0.1), blue hydrangeas (off by 0.1).
• Lime: lawn (cool-season grass) 6.3 lb/100 sq ft over 2 applications; vegetable garden 6.3 lb/100 sq ft over 2 applications; tomatoes 6.3 lb/100 sq ft over 2 applications; roses 6.3 lb/100 sq ft over 2 applications; pink hydrangeas 4.9 lb/100 sq ft.

What to do next

If your test confirms pH near 5.56, spread about 63 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 446,548 surveyed acres in Wake, NC, 69% are moderately acidic (5.5-6.5), 31% are strongly acidic (below 5.5). Mapped soils run from pH 4 to 6.3, a spread of 2.3 units across 201 soil components. 69% 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 12.1% clay and 1.29% 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.

Wake against the rest of North Carolina

pH 5.56 is 0.4 above the North Carolina median of 5.16. 80 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: Caswell (5.54), Durham (5.55), Stokes (5.55), Surry (5.56), Franklin (5.57), Cleveland (5.59), Rutherford (5.6), Warren (5.63).

The range in North Carolina runs from Swain at 4.56 to Davie at 5.9; Wake sits 75% of the way up.