Soil pH in Caribou, ID: Lime or Sulfur?

Typical topsoil pH in Caribou, ID

Typical topsoil in Caribou, ID is pH 6.53, already right for vegetable garden (6-7). Test before adding anything.

What Caribou needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, roses.
• Just outside, test first: strawberries (off by 0), pink hydrangeas (off by 0).
• Sulfur: potatoes 2.3 lb/100 sq ft over 2 applications; blueberries 3.5 lb/100 sq ft over 2 applications; azaleas and rhododendrons 3 lb/100 sq ft over 2 applications; blue hydrangeas 3 lb/100 sq ft over 2 applications.

What to do next

If your test lands near 6.53, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, tomatoes, strawberries, roses, pink hydrangeas.

How mixed the soil is

Of the 374,861 surveyed acres in Caribou, ID, 52% are near neutral (6.5-7.3), 43% are moderately acidic (5.5-6.5), 5% are alkaline (above 7.3). Mapped soils run from pH 4.8 to 8.5, a spread of 3.7 units across 1,350 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 17% clay and 3.23% 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. 1% of mapped components carry free carbonate (lime already in the ground).

Caribou against the rest of Idaho

pH 6.53 is 0.48 below the Idaho median of 7.01. 13 of 44 Idaho counties have more acidic topsoil. Nationally it is more alkaline than the US county median of 6.05.

Closest in pH within the state: Idaho (6.46), Lewis (6.46), Benewah (6.49), Camas (6.49), Adams (6.63), Nez Perce (6.7), Teton (6.87), Blaine (6.91).

The range in Idaho runs from Valley at 6.04 to Jefferson at 8.06; Caribou sits 24% of the way up.