Soil pH in Boundary, ID: Lime or Sulfur?

Typical topsoil pH in Boundary, ID

Typical topsoil in Boundary, ID is pH 6.29, already right for vegetable garden (6-7). Test before adding anything.

What Boundary needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, strawberries, roses, pink hydrangeas.
• Sulfur: potatoes 1 lb/100 sq ft; blueberries 1.6 lb/100 sq ft; azaleas and rhododendrons 1.2 lb/100 sq ft; blue hydrangeas 1.2 lb/100 sq ft.

What to do next

If your test lands near 6.29, 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 713,969 surveyed acres in Boundary, ID, 58% are moderately acidic (5.5-6.5), 35% are near neutral (6.5-7.3), 6% are alkaline (above 7.3), 2% are strongly acidic (below 5.5). Mapped soils run from pH 5 to 7.9, a spread of 2.9 units across 1,427 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 7.2% clay and 4.02% organic matter, which this site treats as sandy. Moving it one pH unit takes about 3 lb of lime or 1.2 lb of sulfur per 100 sq ft. 6% of mapped components carry free carbonate (lime already in the ground).

Boundary against the rest of Idaho

pH 6.29 is 0.72 below the Idaho median of 7.01. 3 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: Valley (6.04), Latah (6.18), Boise (6.25), Clearwater (6.32), Shoshone (6.32), Bonner (6.38), Fremont (6.42).

The range in Idaho runs from Valley at 6.04 to Jefferson at 8.06; Boundary sits 12% of the way up.