Soil pH in Watonwan, MN: Lime or Sulfur?

Typical topsoil pH in Watonwan, MN

Typical topsoil in Watonwan, MN is pH 6.84, already right for vegetable garden (6-7). Test before adding anything.

What Watonwan needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, roses.
• Just outside, test first: tomatoes (off by 0).
• Sulfur: potatoes 4.4 lb/100 sq ft over 3 applications; strawberries 2.7 lb/100 sq ft over 2 applications; blueberries 6.1 lb/100 sq ft over 4 applications; azaleas and rhododendrons 5.4 lb/100 sq ft over 3 applications; blue hydrangeas 5.4 lb/100 sq ft over 3 applications; pink hydrangeas 2 lb/100 sq ft.

What to do next

If your test lands near 6.84, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, tomatoes, roses.

How mixed the soil is

Of the 272,932 surveyed acres in Watonwan, MN, 45% are near neutral (6.5-7.3), 29% are alkaline (above 7.3), 27% are moderately acidic (5.5-6.5). Mapped soils run from pH 5.8 to 7.9, a spread of 2.1 units across 193 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 27.2% clay and 5.79% organic matter, which this site treats as clay. At 5.79% organic matter the soil buffers like a heavier one, which pushes it into the clay bracket. Moving it one pH unit takes about 11.5 lb of lime or 3.4 lb of sulfur per 100 sq ft. 29% of mapped components carry free carbonate (lime already in the ground).

Watonwan against the rest of Minnesota

pH 6.84 is 0.2 above the Minnesota median of 6.64. 55 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: Faribault (6.75), Brown (6.82), Nicollet (6.82), Sibley (6.84), Meeker (6.86), Pipestone (6.86), Murray (6.89), McLeod (6.9).

The range in Minnesota runs from Cook at 5.21 to Swift at 7.49; Watonwan sits 71% of the way up.