Soil pH in Polk, MN: Lime or Sulfur?

Typical topsoil pH in Polk, MN

Typical topsoil in Polk, MN is pH 7.4 and calcareous, so sulfur won't lower it for long. For vegetable garden, choose alkaline-tolerant varieties and add compost rather than fighting the soil.

What Polk needs, by plant

• Beds or pots instead: lawn (cool-season grass), vegetable garden, tomatoes, potatoes, strawberries, roses, blueberries, azaleas and rhododendrons, blue hydrangeas, pink hydrangeas.

What to do next

If your test confirms pH near 7.4, consider raised beds for anything acid-loving; with 65% of soils here carrying free lime, sulfur will not hold.

How mixed the soil is

Of the 1,205,798 surveyed acres in Polk, MN, 58% are alkaline (above 7.3), 42% are near neutral (6.5-7.3). Mapped soils run from pH 5.8 to 8.2, a spread of 2.4 units across 728 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 21.8% clay and 4.36% 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. 65% of mapped components carry free carbonate (lime already in the ground), enough that sulfur gets neutralised before it does much.

Polk against the rest of Minnesota

pH 7.4 is 0.76 above the Minnesota median of 6.64. 83 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: Big Stone (7.36), Chippewa (7.37), Kittson (7.37), Marshall (7.37), Clay (7.43), Norman (7.49), Swift (7.49).

The range in Minnesota runs from Cook at 5.21 to Swift at 7.49; Polk sits 96% of the way up.