Soil pH in Guthrie, IA: Lime or Sulfur?

Typical topsoil pH in Guthrie, IA

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

What Guthrie 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 375,253 surveyed acres in Guthrie, IA, 67% are moderately acidic (5.5-6.5), 30% are near neutral (6.5-7.3), 3% are alkaline (above 7.3). Mapped soils run from pH 5.7 to 7.9, a spread of 2.2 units across 346 soil components. 67% 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 27.7% clay and 3.61% 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. 4% of mapped components carry free carbonate (lime already in the ground).

Guthrie 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: Appanoose (6.22), Davis (6.22), Adair (6.25), Adams (6.25), Iowa (6.25), Lucas (6.25), Decatur (6.26), Jasper (6.27).

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