Soil pH in Rock, MN: Lime or Sulfur?

Typical topsoil pH in Rock, MN

Typical topsoil in Rock, MN is pH 6.67, already right for vegetable garden (6-7). Test before adding anything.

What Rock needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, roses.
• Just outside, test first: strawberries (off by 0.2), pink hydrangeas (off by 0.2).
• Sulfur: potatoes 4.1 lb/100 sq ft over 3 applications; blueberries 5.8 lb/100 sq ft over 3 applications; azaleas and rhododendrons 4.8 lb/100 sq ft over 3 applications; blue hydrangeas 4.8 lb/100 sq ft over 3 applications.

What to do next

If your test lands near 6.67, 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 306,215 surveyed acres in Rock, MN, 75% are near neutral (6.5-7.3), 17% are moderately acidic (5.5-6.5), 8% are alkaline (above 7.3). Mapped soils run from pH 5.6 to 8.2, a spread of 2.6 units across 222 soil components. 75% 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 29.7% clay and 4.71% 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. 9% of mapped components carry free carbonate (lime already in the ground).

Rock against the rest of Minnesota

pH 6.67 is right at the Minnesota median of 6.64. 45 of 87 Minnesota counties have more acidic topsoil. Nationally it is more alkaline than the US county median of 6.05.

Closest in pH within the state: Waseca (6.62), Blue Earth (6.64), Freeborn (6.64), Becker (6.65), Lake of the Woods (6.68), Stearns (6.69), Scott (6.7), Cottonwood (6.72).

The range in Minnesota runs from Cook at 5.21 to Swift at 7.49; Rock sits 64% of the way up.