Soil pH in Adams, ID: Lime or Sulfur?

Typical topsoil pH in Adams, ID

Typical topsoil in Adams, ID is pH 6.63, already right for vegetable garden (6-7). Test before adding anything.

What Adams needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, roses.
• Just outside, test first: strawberries (off by 0.1), pink hydrangeas (off by 0.1).
• Sulfur: potatoes 2.5 lb/100 sq ft over 2 applications; blueberries 3.7 lb/100 sq ft over 2 applications; azaleas and rhododendrons 3.2 lb/100 sq ft over 2 applications; blue hydrangeas 3.2 lb/100 sq ft over 2 applications.

What to do next

If your test lands near 6.63, 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 270,893 surveyed acres in Adams, ID, 85% are near neutral (6.5-7.3), 14% are moderately acidic (5.5-6.5), 1% are strongly acidic (below 5.5). Mapped soils run from pH 5 to 8.2, a spread of 3.2 units across 166 soil components. 85% 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 20% clay and 3.24% 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. None of the mapped components carry free carbonate.

Adams against the rest of Idaho

pH 6.63 is 0.38 below the Idaho median of 7.01. 14 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: Lewis (6.46), Benewah (6.49), Camas (6.49), Caribou (6.53), Nez Perce (6.7), Teton (6.87), Blaine (6.91), Bannock (6.93).

The range in Idaho runs from Valley at 6.04 to Jefferson at 8.06; Adams sits 29% of the way up.