Soil pH in Arlington, VA: Lime or Sulfur?

Typical topsoil pH in Arlington, VA

Typical topsoil in Arlington, VA is pH 4.95, 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 Arlington 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 4.95, 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 4,143 surveyed acres in Arlington, VA, 91% are strongly acidic (below 5.5), 10% are moderately acidic (5.5-6.5). Mapped soils run from pH 4.6 to 5.9, a spread of 1.3 units across 32 soil components. 91% 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 19.1% clay and 1.79% 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.

Arlington against the rest of Virginia

pH 4.95 is 0.29 below the Virginia median of 5.24. 18 of 127 Virginia counties have more acidic topsoil. Nationally it is more acidic than the US county median of 6.05.

Closest in pH within the state: Isle of Wight (4.93), Essex (4.94), Chesapeake City (4.94), Hampton City (4.94), Prince George (4.95), Fredericksburg City (4.95), Henry (4.96), Highland (4.96).

The range in Virginia runs from Newport News City at 4.76 to Poquoson City at 6.36; Arlington sits 12% of the way up.