Soil pH in St. Croix, WI: Lime or Sulfur?

Typical topsoil pH in St. Croix, WI

Typical topsoil in St. Croix, WI is pH 6.06, already right for vegetable garden (6-7). Test before adding anything.

What St. Croix needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, strawberries, roses, pink hydrangeas.
• Just outside, test first: tomatoes (off by 0.1), potatoes (off by 0.1), azaleas and rhododendrons (off by 0.1).
• Sulfur: blueberries 2.5 lb/100 sq ft over 2 applications; blue hydrangeas 1.8 lb/100 sq ft.

What to do next

If your test lands near 6.06, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, tomatoes, potatoes, strawberries, roses, azaleas and rhododendrons, pink hydrangeas.

How mixed the soil is

Of the 452,697 surveyed acres in St. Croix, WI, 79% are moderately acidic (5.5-6.5), 17% are near neutral (6.5-7.3), 3% are strongly acidic (below 5.5). Mapped soils run from pH 5 to 7, a spread of 2 units across 497 soil components. 79% 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 13.9% 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. None of the mapped components carry free carbonate.

St. Croix against the rest of Wisconsin

pH 6.06 is right at the Wisconsin median of 6.08. 32 of 72 Wisconsin counties have more acidic topsoil. Nationally it is more alkaline than the US county median of 6.05.

Closest in pH within the state: Shawano (5.98), Trempealeau (6), Dunn (6.06), Oconto (6.06), Buffalo (6.08), Waupaca (6.09), La Crosse (6.12), Pepin (6.12).

The range in Wisconsin runs from Iron at 5.16 to Washington at 6.88; St. Croix sits 52% of the way up.