Soil pH in Carbon, MT: Lime or Sulfur?

Typical topsoil pH in Carbon, MT

Typical topsoil in Carbon, MT is pH 7.32 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 Carbon 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 7.32, consider raised beds for anything acid-loving; with 39% of soils here carrying free lime, sulfur will not hold.

How mixed the soil is

Of the 903,341 surveyed acres in Carbon, MT, 50% are near neutral (6.5-7.3), 49% are alkaline (above 7.3), 1% are moderately acidic (5.5-6.5). Mapped soils run from pH 6.1 to 9, a spread of 2.9 units across 590 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 27.9% clay and 2.32% 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. 39% of mapped components carry free carbonate (lime already in the ground), enough that sulfur gets neutralised before it does much.

Carbon against the rest of Montana

pH 7.32 is right at the Montana median of 7.3. 28 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: Sweet Grass (7.25), Cascade (7.27), Daniels (7.28), Fergus (7.28), Liberty (7.32), Stillwater (7.33), Toole (7.33), Carter (7.34).

The range in Montana runs from Flathead at 6.02 to Wheatland at 7.77; Carbon sits 74% of the way up.