Soil pH in Douglas, WA: Lime or Sulfur?

Typical topsoil pH in Douglas, WA

Typical topsoil in Douglas, WA is pH 6.88, already right for vegetable garden (6-7). Test before adding anything.

What Douglas needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, roses.
• Just outside, test first: tomatoes (off by 0.1).
• Sulfur: potatoes 1.7 lb/100 sq ft; strawberries 1.1 lb/100 sq ft; blueberries 2.3 lb/100 sq ft over 2 applications; azaleas and rhododendrons 1.9 lb/100 sq ft; blue hydrangeas 1.9 lb/100 sq ft; pink hydrangeas 0.7 lb/100 sq ft.

What to do next

If your test lands near 6.88, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, tomatoes, roses.

How mixed the soil is

Of the 0 surveyed acres in Douglas, WA, 96% are near neutral (6.5-7.3), 4% are alkaline (above 7.3). Mapped soils run from pH 6.3 to 10.1, a spread of 3.8 units across 843 soil components. 96% 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 9.2% clay and 1.6% 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. 3% of mapped components carry free carbonate (lime already in the ground).

Douglas against the rest of Washington

pH 6.88 is 0.47 above the Washington median of 6.41. 29 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: Ferry (6.61), Stevens (6.73), Whitman (6.75), Yakima (6.83), Garfield (7.01), Asotin (7.04), Columbia (7.05), Lincoln (7.12).

The range in Washington runs from Grays Harbor at 4.93 to Adams at 7.45; Douglas sits 77% of the way up.