Soil pH in Benton, WA: Lime or Sulfur?

Typical topsoil pH in Benton, WA

Typical topsoil in Benton, WA is pH 7.44, too alkaline for vegetable garden. Expect roughly 1.1 lb of sulfur per 100 sq ft, but only after a soil test confirms it.

What Benton needs, by plant

• Sulfur: lawn (cool-season grass) 1.1 lb/100 sq ft; vegetable garden 1.1 lb/100 sq ft; tomatoes 1.1 lb/100 sq ft; potatoes 2.3 lb/100 sq ft over 2 applications; strawberries 1.7 lb/100 sq ft; roses 1.1 lb/100 sq ft; blueberries 2.9 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 7.44, work in about 11 lb of elemental sulfur per 1,000 sq ft of vegetable bed.

How mixed the soil is

Of the 1,055,327 surveyed acres in Benton, WA, 62% are alkaline (above 7.3), 38% are near neutral (6.5-7.3). Mapped soils run from pH 6.7 to 9, a spread of 2.3 units across 155 soil components. 62% 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 7.5% clay and 1.25% 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. 1% of mapped components carry free carbonate (lime already in the ground).

Benton against the rest of Washington

pH 7.44 is 1.03 above the Washington median of 6.41. 37 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: Lincoln (7.12), Walla Walla (7.23), Franklin (7.32), Grant (7.37), Adams (7.45).

The range in Washington runs from Grays Harbor at 4.93 to Adams at 7.45; Benton sits 100% of the way up.