Soil pH in Adams, WA: Lime or Sulfur?

Typical topsoil pH in Adams, WA

Typical topsoil in Adams, WA is pH 7.45, too alkaline for vegetable garden. Expect roughly 1.2 lb of sulfur per 100 sq ft, but only after a soil test confirms it.

What Adams needs, by plant

• Sulfur: lawn (cool-season grass) 1.2 lb/100 sq ft; vegetable garden 1.2 lb/100 sq ft; tomatoes 1.2 lb/100 sq ft; potatoes 2.4 lb/100 sq ft over 2 applications; strawberries 1.8 lb/100 sq ft; roses 1.2 lb/100 sq ft; blueberries 3 lb/100 sq ft over 2 applications; azaleas and rhododendrons 2.6 lb/100 sq ft over 2 applications; blue hydrangeas 2.6 lb/100 sq ft over 2 applications; pink hydrangeas 1.4 lb/100 sq ft.

What to do next

If your test confirms pH near 7.45, work in about 12 lb of elemental sulfur per 1,000 sq ft of vegetable bed.

How mixed the soil is

Of the 1,165,407 surveyed acres in Adams, WA, 55% are alkaline (above 7.3), 45% are near neutral (6.5-7.3). Mapped soils run from pH 6.7 to 9.3, a spread of 2.6 units across 203 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 8.8% clay and 1.52% 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).

Adams against the rest of Washington

pH 7.45 is 1.04 above the Washington median of 6.41. 38 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: Walla Walla (7.23), Franklin (7.32), Grant (7.37), Benton (7.44).