Soil pH in Caddo, OK: Lime or Sulfur?

Typical topsoil pH in Caddo, OK

Typical topsoil in Caddo, OK is pH 6.64, already right for vegetable garden (6-7). Test before adding anything.

What Caddo needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, roses.
• Just outside, test first: strawberries (off by 0.1), pink hydrangeas (off by 0.1).
• Sulfur: potatoes 2.5 lb/100 sq ft over 2 applications; blueberries 3.7 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 6.64, 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 749,004 surveyed acres in Caddo, OK, 57% are near neutral (6.5-7.3), 34% are moderately acidic (5.5-6.5), 9% are alkaline (above 7.3). Mapped soils run from pH 5.6 to 8.2, a spread of 2.6 units across 142 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% clay and 1.45% 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. 6% of mapped components carry free carbonate (lime already in the ground).

Caddo against the rest of Oklahoma

pH 6.64 is 0.09 above the Oklahoma median of 6.55. 46 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: Love (6.59), Garvin (6.6), Lincoln (6.6), Payne (6.62), Carter (6.65), Jefferson (6.71), Kay (6.74), McClain (6.77).

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