Soil pH in Oklahoma, OK: Lime or Sulfur?

Typical topsoil pH in Oklahoma, OK

Typical topsoil in Oklahoma, OK is pH 6.35, already right for vegetable garden (6-7). Test before adding anything.

What Oklahoma needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, strawberries, roses, pink hydrangeas.
• Sulfur: potatoes 1.8 lb/100 sq ft; blueberries 3 lb/100 sq ft over 2 applications; azaleas and rhododendrons 2.5 lb/100 sq ft over 2 applications; blue hydrangeas 2.5 lb/100 sq ft over 2 applications.

What to do next

If your test lands near 6.35, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, tomatoes, strawberries, roses, pink hydrangeas.

How mixed the soil is

Of the 343,313 surveyed acres in Oklahoma, OK, 55% are moderately acidic (5.5-6.5), 31% are near neutral (6.5-7.3), 10% are alkaline (above 7.3), 4% are strongly acidic (below 5.5). Mapped soils run from pH 5.3 to 8.2, a spread of 2.9 units across 209 soil components. No single class covers 60% of the county, so two gardens a few miles apart here can need opposite treatments. Test your own bed.

Clay, organic matter and rates

Topsoil here averages 16.9% clay and 1.78% 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. 7% of mapped components carry free carbonate (lime already in the ground).

Oklahoma against the rest of Oklahoma

pH 6.35 is 0.2 below the Oklahoma median of 6.55. 30 of 77 Oklahoma counties have more acidic topsoil. Nationally it is more alkaline than the US county median of 6.05.

Closest in pH within the state: Washington (6.19), Pontotoc (6.27), Seminole (6.33), Osage (6.34), Stephens (6.35), Bryan (6.37), Cleveland (6.4), Johnston (6.42).

The range in Oklahoma runs from Adair at 5.12 to Beaver at 7.65; Oklahoma sits 49% of the way up.