Soil pH in Douglas, SD: Lime or Sulfur?

Typical topsoil pH in Douglas, SD

Typical topsoil in Douglas, SD is pH 6.76, 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, roses.
• Sulfur: potatoes 3 lb/100 sq ft over 2 applications; strawberries 1.8 lb/100 sq ft; blueberries 4.1 lb/100 sq ft over 3 applications; azaleas and rhododendrons 3.5 lb/100 sq ft over 2 applications; blue hydrangeas 3.5 lb/100 sq ft over 2 applications; pink hydrangeas 1.2 lb/100 sq ft.

What to do next

If your test lands near 6.76, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, tomatoes, roses.

How mixed the soil is

Of the 277,573 surveyed acres in Douglas, SD, 58% are near neutral (6.5-7.3), 27% are moderately acidic (5.5-6.5), 15% are alkaline (above 7.3). Mapped soils run from pH 6.3 to 7.9, a spread of 1.6 units across 213 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 23% clay and 3.49% 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. 16% of mapped components carry free carbonate (lime already in the ground).

Douglas against the rest of South Dakota

pH 6.76 is 0.23 below the South Dakota median of 6.99. 3 of 66 South Dakota counties have more acidic topsoil. Nationally it is more alkaline than the US county median of 6.05.

Closest in pH within the state: Lawrence (6.49), Sully (6.64), Lake (6.71), Lincoln (6.76), Moody (6.78), Potter (6.78), Hughes (6.8).

The range in South Dakota runs from Lawrence at 6.49 to Jones at 7.47; Douglas sits 28% of the way up.