Soil pH in Carter, OK: Lime or Sulfur?

Typical topsoil pH in Carter, OK

Typical topsoil in Carter, OK is pH 6.65, already right for vegetable garden (6-7). Test before adding anything.

What Carter needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, roses.
• Just outside, test first: strawberries (off by 0.2), pink hydrangeas (off by 0.2).
• Sulfur: potatoes 2.8 lb/100 sq ft over 2 applications; blueberries 3.9 lb/100 sq ft over 2 applications; azaleas and rhododendrons 3.2 lb/100 sq ft over 2 applications; blue hydrangeas 3.2 lb/100 sq ft over 2 applications.

What to do next

If your test lands near 6.65, 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 475,598 surveyed acres in Carter, OK, 44% are moderately acidic (5.5-6.5), 40% are near neutral (6.5-7.3), 17% are alkaline (above 7.3). Mapped soils run from pH 5.8 to 8.2, a spread of 2.4 units across 132 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 18.8% clay and 1.3% 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. 12% of mapped components carry free carbonate (lime already in the ground).

Carter against the rest of Oklahoma

pH 6.65 is 0.1 above the Oklahoma median of 6.55. 47 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: Garvin (6.6), Lincoln (6.6), Payne (6.62), Caddo (6.64), Jefferson (6.71), Kay (6.74), McClain (6.77), Kingfisher (6.78).

The range in Oklahoma runs from Adair at 5.12 to Beaver at 7.65; Carter sits 60% of the way up.