Soil pH in Sweet Grass, MT: Lime or Sulfur?

Typical topsoil pH in Sweet Grass, MT

Typical topsoil in Sweet Grass, MT is pH 7.25 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 Sweet Grass 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 7.25, consider raised beds for anything acid-loving; with 33% of soils here carrying free lime, sulfur will not hold.

How mixed the soil is

Of the 957,893 surveyed acres in Sweet Grass, MT, 56% are near neutral (6.5-7.3), 37% are alkaline (above 7.3), 7% are moderately acidic (5.5-6.5). Mapped soils run from pH 5.2 to 8.2, a spread of 3 units across 1,835 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 22.6% clay and 2.51% 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. 33% of mapped components carry free carbonate (lime already in the ground), enough that sulfur gets neutralised before it does much.

Sweet Grass against the rest of Montana

pH 7.25 is 0.05 below the Montana median of 7.3. 24 of 56 Montana counties have more acidic topsoil. Nationally it is more alkaline than the US county median of 6.05.

Closest in pH within the state: Phillips (7.17), Blaine (7.19), Valley (7.19), Chouteau (7.24), Cascade (7.27), Daniels (7.28), Fergus (7.28), Carbon (7.32).

The range in Montana runs from Flathead at 6.02 to Wheatland at 7.77; Sweet Grass sits 70% of the way up.