Soil pH in Macoupin, IL: Lime or Sulfur?

Typical topsoil pH in Macoupin, IL

Typical topsoil in Macoupin, IL is pH 6.41, already right for vegetable garden (6-7). Test before adding anything.

What Macoupin needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, strawberries, roses, pink hydrangeas.
• Sulfur: potatoes 2.1 lb/100 sq ft over 2 applications; blueberries 3.2 lb/100 sq ft over 2 applications; azaleas and rhododendrons 2.8 lb/100 sq ft over 2 applications; blue hydrangeas 2.8 lb/100 sq ft over 2 applications.

What to do next

If your test lands near 6.41, 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 537,528 surveyed acres in Macoupin, IL, 63% are near neutral (6.5-7.3), 37% are moderately acidic (5.5-6.5). Mapped soils run from pH 5.1 to 7.9, a spread of 2.8 units across 189 soil components. 63% 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 21.9% clay and 2.99% 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. None of the mapped components carry free carbonate.

Macoupin against the rest of Illinois

pH 6.41 is right at the Illinois median of 6.4. 53 of 102 Illinois counties have more acidic topsoil. Nationally it is more alkaline than the US county median of 6.05.

Closest in pH within the state: Hancock (6.4), Mason (6.4), Piatt (6.4), Carroll (6.41), Moultrie (6.41), Woodford (6.41), Christian (6.43), Cumberland (6.43).

The range in Illinois runs from Pope at 5.5 to Grundy at 6.75; Macoupin sits 73% of the way up.