Soil pH in Whitman, WA: Lime or Sulfur?

Typical topsoil pH in Whitman, WA

Typical topsoil in Whitman, WA is pH 6.75, already right for vegetable garden (6-7). Test before adding anything.

What Whitman needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, roses.
• Sulfur: potatoes 3 lb/100 sq ft over 2 applications; strawberries 1.8 lb/100 sq ft; blueberries 4.1 lb/100 sq ft over 3 applications; azaleas and rhododendrons 3.5 lb/100 sq ft over 2 applications; blue hydrangeas 3.5 lb/100 sq ft over 2 applications; pink hydrangeas 1.2 lb/100 sq ft.

What to do next

If your test lands near 6.75, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, tomatoes, roses.

How mixed the soil is

Of the 1,312,584 surveyed acres in Whitman, WA, 78% are near neutral (6.5-7.3), 14% are moderately acidic (5.5-6.5), 8% are alkaline (above 7.3). Mapped soils run from pH 5.5 to 8.8, a spread of 3.3 units across 175 soil components. 78% 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 16.9% clay and 2.86% 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. 5% of mapped components carry free carbonate (lime already in the ground).

Whitman against the rest of Washington

pH 6.75 is 0.34 above the Washington median of 6.41. 27 of 39 Washington counties have more acidic topsoil. Nationally it is more alkaline than the US county median of 6.05.

Closest in pH within the state: Chelan (6.5), Klickitat (6.53), Ferry (6.61), Stevens (6.73), Yakima (6.83), Douglas (6.88), Garfield (7.01), Asotin (7.04).

The range in Washington runs from Grays Harbor at 4.93 to Adams at 7.45; Whitman sits 72% of the way up.