Soil pH in Scott, IA: Lime or Sulfur?

Typical topsoil pH in Scott, IA

Typical topsoil in Scott, IA is pH 6.33, already right for vegetable garden (6-7). Test before adding anything.

What Scott needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, strawberries, roses, pink hydrangeas.
• Sulfur: potatoes 1.8 lb/100 sq ft; blueberries 3 lb/100 sq ft over 2 applications; azaleas and rhododendrons 2.5 lb/100 sq ft over 2 applications; blue hydrangeas 2.5 lb/100 sq ft over 2 applications.

What to do next

If your test lands near 6.33, 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 279,740 surveyed acres in Scott, IA, 61% are near neutral (6.5-7.3), 38% are moderately acidic (5.5-6.5). Mapped soils run from pH 4.2 to 7.5, a spread of 3.3 units across 327 soil components. 61% 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 25.5% clay and 3.37% 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).

Scott against the rest of Iowa

pH 6.33 is right at the Iowa median of 6.36. 37 of 99 Iowa counties have more acidic topsoil. Nationally it is more alkaline than the US county median of 6.05.

Closest in pH within the state: Johnson (6.31), Mahaska (6.31), Washington (6.31), Muscatine (6.33), Tama (6.33), Carroll (6.34), Clinton (6.34), Delaware (6.34).

The range in Iowa runs from Van Buren at 6.02 to Monona at 7.11; Scott sits 28% of the way up.