Soil pH in Douglas, IL: Lime or Sulfur?

Typical topsoil pH in Douglas, IL

Typical topsoil in Douglas, IL is pH 6.48, already right for vegetable garden (6-7). Test before adding anything.

What Douglas needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, strawberries, roses, pink hydrangeas.
• Sulfur: potatoes 3.4 lb/100 sq ft over 2 applications; blueberries 5.1 lb/100 sq ft over 3 applications; azaleas and rhododendrons 4.1 lb/100 sq ft over 3 applications; blue hydrangeas 4.1 lb/100 sq ft over 3 applications.

What to do next

If your test lands near 6.48, 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 264,114 surveyed acres in Douglas, IL, 55% are near neutral (6.5-7.3), 45% are moderately acidic (5.5-6.5), 1% are alkaline (above 7.3). Mapped soils run from pH 4.5 to 8.2, a spread of 3.7 units across 125 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 28.7% clay and 4.5% organic matter, which this site treats as clay. Moving it one pH unit takes about 11.5 lb of lime or 3.4 lb of sulfur per 100 sq ft. 1% of mapped components carry free carbonate (lime already in the ground).

Douglas against the rest of Illinois

pH 6.48 is 0.08 above the Illinois median of 6.4. 73 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: Peoria (6.46), Stephenson (6.46), Fulton (6.47), Putnam (6.47), Marshall (6.5), La Salle (6.51), Menard (6.51), Rock Island (6.51).

The range in Illinois runs from Pope at 5.5 to Grundy at 6.75; Douglas sits 78% of the way up.