Soil pH in Williamson, IL: Lime or Sulfur?

Typical topsoil pH in Williamson, IL

Typical topsoil in Williamson, IL is pH 5.92, just outside the 6-7 range for vegetable garden. Test first; it may need nothing.

What Williamson needs, by plant

• Already in range: potatoes, strawberries, azaleas and rhododendrons.
• Just outside, test first: lawn (cool-season grass) (off by 0.1), vegetable garden (off by 0.1), roses (off by 0.1), pink hydrangeas (off by 0.1).
• Lime: tomatoes 4.2 lb/100 sq ft.
• Sulfur: blueberries 2.1 lb/100 sq ft over 2 applications; blue hydrangeas 1.6 lb/100 sq ft.

What to do next

If your test lands near 5.92, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, potatoes, strawberries, roses, azaleas and rhododendrons, pink hydrangeas.

How mixed the soil is

Of the 254,176 surveyed acres in Williamson, IL, 62% are moderately acidic (5.5-6.5), 20% are near neutral (6.5-7.3), 17% are strongly acidic (below 5.5). Mapped soils run from pH 4.8 to 7.5, a spread of 2.7 units across 235 soil components. 62% 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 20.4% clay and 1.54% 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. 0% of mapped components carry free carbonate (lime already in the ground).

Williamson against the rest of Illinois

pH 5.92 is 0.48 below the Illinois median of 6.4. 4 of 102 Illinois counties have more acidic topsoil. Nationally it is more acidic than the US county median of 6.05.

Closest in pH within the state: Pope (5.5), Johnson (5.56), Hardin (5.65), Massac (5.81), Pulaski (6.02), Union (6.02), Jefferson (6.03), Saline (6.11).

The range in Illinois runs from Pope at 5.5 to Grundy at 6.75; Williamson sits 34% of the way up.