Soil pH in Pottawattamie, IA: Lime or Sulfur?

Typical topsoil pH in Pottawattamie, IA

Typical topsoil in Pottawattamie, IA is pH 6.52, already right for vegetable garden (6-7). Test before adding anything.

What Pottawattamie needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, roses.
• Just outside, test first: strawberries (off by 0), pink hydrangeas (off by 0).
• Sulfur: potatoes 2.3 lb/100 sq ft over 2 applications; blueberries 3.5 lb/100 sq ft over 2 applications; azaleas and rhododendrons 3 lb/100 sq ft over 2 applications; blue hydrangeas 3 lb/100 sq ft over 2 applications.

What to do next

If your test lands near 6.52, 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 603,875 surveyed acres in Pottawattamie, IA, 62% are moderately acidic (5.5-6.5), 19% are near neutral (6.5-7.3), 18% are alkaline (above 7.3). Mapped soils run from pH 5.5 to 8, a spread of 2.5 units across 301 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 26.7% clay and 2.91% 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. 22% of mapped components carry free carbonate (lime already in the ground).

Pottawattamie against the rest of Iowa

pH 6.52 is 0.16 above the Iowa median of 6.36. 70 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: Floyd (6.46), Lyon (6.5), Fremont (6.51), Buena Vista (6.52), Polk (6.53), Mills (6.54), Hardin (6.56), Osceola (6.56).

The range in Iowa runs from Van Buren at 6.02 to Monona at 7.11; Pottawattamie sits 46% of the way up.