Soil pH in St. Francois, MO: Lime or Sulfur?

Typical topsoil pH in St. Francois, MO

Typical topsoil in St. Francois, MO is pH 5.74, too acidic for vegetable garden. Expect roughly 5.6 lb of lime per 100 sq ft, but only after a soil test confirms it.

What St. Francois needs, by plant

• Already in range: potatoes, strawberries, azaleas and rhododendrons.
• Just outside, test first: blueberries (off by 0.2), blue hydrangeas (off by 0.2).
• Lime: lawn (cool-season grass) 5.6 lb/100 sq ft over 2 applications; vegetable garden 5.6 lb/100 sq ft over 2 applications; tomatoes 5.6 lb/100 sq ft over 2 applications; roses 5.6 lb/100 sq ft over 2 applications; pink hydrangeas 3.5 lb/100 sq ft.

What to do next

If your test confirms pH near 5.74, spread about 56 lb of ground limestone per 1,000 sq ft of vegetable bed in 2 doses, ideally in fall.

How mixed the soil is

Of the 281,339 surveyed acres in St. Francois, MO, 45% are strongly acidic (below 5.5), 31% are moderately acidic (5.5-6.5), 23% are near neutral (6.5-7.3), 1% are alkaline (above 7.3). Mapped soils run from pH 4.5 to 7.8, a spread of 3.3 units across 423 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 14% clay and 3.43% 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. 1% of mapped components carry free carbonate (lime already in the ground).

St. Francois against the rest of Missouri

pH 5.74 is 0.39 below the Missouri median of 6.13. 28 of 114 Missouri counties have more acidic topsoil. Nationally it is more acidic than the US county median of 6.05.

Closest in pH within the state: Butler (5.66), Ozark (5.67), Ste. Genevieve (5.67), Laclede (5.74), Dade (5.78), Cedar (5.79), Benton (5.84), Barton (5.85).

The range in Missouri runs from Carter at 5.08 to Knox at 6.71; St. Francois sits 40% of the way up.