Soil pH in Harrison, IA: Lime or Sulfur?

Typical topsoil pH in Harrison, IA

Typical topsoil in Harrison, IA is pH 6.91, already right for vegetable garden (6-7). Test before adding anything.

What Harrison needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, roses.
• Just outside, test first: tomatoes (off by 0.1).
• Beds or pots instead: potatoes, strawberries, blueberries, azaleas and rhododendrons, blue hydrangeas, pink hydrangeas.

What to do next

If your test lands near 6.91, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, tomatoes, roses.

How mixed the soil is

Of the 442,530 surveyed acres in Harrison, IA, 38% are near neutral (6.5-7.3), 31% are moderately acidic (5.5-6.5), 31% are alkaline (above 7.3). Mapped soils run from pH 6 to 8, a spread of 2 units across 236 soil components. No single class covers 60% of the county, so two gardens a few miles apart here can need opposite treatments. Test your own bed.

Clay, organic matter and rates

Topsoil here averages 26.2% clay and 2.84% 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. 44% of mapped components carry free carbonate (lime already in the ground), enough that sulfur gets neutralised before it does much.

Harrison against the rest of Iowa

pH 6.91 is 0.55 above the Iowa median of 6.36. 97 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: Kossuth (6.78), Humboldt (6.79), Hancock (6.8), Woodbury (6.89), Monona (7.11).

The range in Iowa runs from Van Buren at 6.02 to Monona at 7.11; Harrison sits 82% of the way up.