Soil pH in Adams, IA: Lime or Sulfur?

Typical topsoil pH in Adams, IA

Typical topsoil in Adams, IA is pH 6.25, already right for vegetable garden (6-7). Test before adding anything.

What Adams needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, strawberries, roses, pink hydrangeas.
• Sulfur: potatoes 2.7 lb/100 sq ft over 2 applications; blueberries 4.4 lb/100 sq ft over 3 applications; azaleas and rhododendrons 3.4 lb/100 sq ft over 2 applications; blue hydrangeas 3.4 lb/100 sq ft over 2 applications.

What to do next

If your test lands near 6.25, 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 262,852 surveyed acres in Adams, IA, 70% are moderately acidic (5.5-6.5), 30% are near neutral (6.5-7.3). Mapped soils run from pH 5.5 to 6.9, a spread of 1.4 units across 243 soil components. 70% 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 31% clay and 3.46% 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. None of the mapped components carry free carbonate.

Adams against the rest of Iowa

pH 6.25 is 0.11 below the Iowa median of 6.36. 18 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: Wapello (6.21), Appanoose (6.22), Davis (6.22), Adair (6.25), Guthrie (6.25), Iowa (6.25), Lucas (6.25), Decatur (6.26).

The range in Iowa runs from Van Buren at 6.02 to Monona at 7.11; Adams sits 21% of the way up.