Soil pH in Iredell, NC: Lime or Sulfur?

Typical topsoil pH in Iredell, NC

Typical topsoil in Iredell, NC is pH 5.82, just outside the 6-7 range for vegetable garden. Test first; it may need nothing.

What Iredell needs, by plant

• Already in range: potatoes, strawberries, azaleas and rhododendrons.
• Just outside, test first: lawn (cool-season grass) (off by 0.2), vegetable garden (off by 0.2), roses (off by 0.2), pink hydrangeas (off by 0.2).
• Lime: tomatoes 4.9 lb/100 sq ft.
• Sulfur: blueberries 1.8 lb/100 sq ft; blue hydrangeas 1.4 lb/100 sq ft.

What to do next

If your test lands near 5.82, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, potatoes, strawberries, roses, azaleas and rhododendrons, pink hydrangeas.

How mixed the soil is

Of the 334,528 surveyed acres in Iredell, NC, 88% are moderately acidic (5.5-6.5), 11% are strongly acidic (below 5.5), 1% are near neutral (6.5-7.3). Mapped soils run from pH 4.5 to 7, a spread of 2.5 units across 345 soil components. 88% 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 24.3% clay and 1.18% 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.

Iredell against the rest of North Carolina

pH 5.82 is 0.66 above the North Carolina median of 5.16. 98 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: Vance (5.77), Yadkin (5.77), Guilford (5.8), Lincoln (5.81), Davie (5.9).

The range in North Carolina runs from Swain at 4.56 to Davie at 5.9; Iredell sits 94% of the way up.