Soil pH in Clayton, IA: Lime or Sulfur?

Typical topsoil pH in Clayton, IA

Typical topsoil in Clayton, IA is pH 6.45, already right for vegetable garden (6-7). Test before adding anything.

What Clayton needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, strawberries, roses, pink hydrangeas.
• Sulfur: potatoes 2.3 lb/100 sq ft over 2 applications; blueberries 3.5 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 6.45, 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 476,934 surveyed acres in Clayton, IA, 62% are moderately acidic (5.5-6.5), 31% are near neutral (6.5-7.3), 7% are alkaline (above 7.3). Mapped soils run from pH 5.5 to 8.2, a spread of 2.7 units across 332 soil components. 62% 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 20.9% clay and 2.36% 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. 7% of mapped components carry free carbonate (lime already in the ground).

Clayton against the rest of Iowa

pH 6.45 is 0.09 above the Iowa median of 6.36. 65 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: Fayette (6.4), Bremer (6.41), Jackson (6.41), Jones (6.41), Allamakee (6.46), Floyd (6.46), Lyon (6.5), Fremont (6.51).

The range in Iowa runs from Van Buren at 6.02 to Monona at 7.11; Clayton sits 39% of the way up.