Soil pH in Stillwater, MT: Lime or Sulfur?

Typical topsoil pH in Stillwater, MT

Typical topsoil in Stillwater, MT is pH 7.33, too alkaline for vegetable garden. Expect roughly 1.8 lb of sulfur per 100 sq ft, but only after a soil test confirms it.

What Stillwater needs, by plant

• Sulfur: lawn (cool-season grass) 1.8 lb/100 sq ft; vegetable garden 1.8 lb/100 sq ft; tomatoes 1.8 lb/100 sq ft; potatoes 4.1 lb/100 sq ft over 3 applications; strawberries 3 lb/100 sq ft over 2 applications; roses 1.8 lb/100 sq ft; blueberries 5.3 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; pink hydrangeas 2.5 lb/100 sq ft over 2 applications.

What to do next

If your test confirms pH near 7.33, work in about 18 lb of elemental sulfur per 1,000 sq ft of vegetable bed.

How mixed the soil is

Of the 903,110 surveyed acres in Stillwater, MT, 63% are near neutral (6.5-7.3), 36% are alkaline (above 7.3). Mapped soils run from pH 5.6 to 8.8, a spread of 3.2 units across 536 soil components. 63% 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 25.9% clay and 2.42% 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. 28% of mapped components carry free carbonate (lime already in the ground).

Stillwater against the rest of Montana

pH 7.33 is right at the Montana median of 7.3. 30 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: Daniels (7.28), Fergus (7.28), Carbon (7.32), Liberty (7.32), Toole (7.33), Carter (7.34), Judith Basin (7.34), Petroleum (7.34).

The range in Montana runs from Flathead at 6.02 to Wheatland at 7.77; Stillwater sits 75% of the way up.