Soil pH in Clatsop, OR: Lime or Sulfur?

Typical topsoil pH in Clatsop, OR

Typical topsoil in Clatsop, OR is pH 4.89, too acidic for vegetable garden. Expect roughly 18.4 lb of lime per 100 sq ft, but only after a soil test confirms it.

What Clatsop needs, by plant

• Already in range: blueberries, azaleas and rhododendrons.
• Just outside, test first: potatoes (off by 0.1), blue hydrangeas (off by 0.1).
• Lime: lawn (cool-season grass) 18.4 lb/100 sq ft over 4 applications; vegetable garden 18.4 lb/100 sq ft over 4 applications; tomatoes 18.4 lb/100 sq ft over 4 applications; strawberries 12.7 lb/100 sq ft over 3 applications; roses 18.4 lb/100 sq ft over 4 applications; pink hydrangeas 16.1 lb/100 sq ft over 4 applications.

What to do next

If your test confirms pH near 4.89, spread about 184 lb of ground limestone per 1,000 sq ft of vegetable bed in 4 doses, ideally in fall.

How mixed the soil is

Of the 414,184 surveyed acres in Clatsop, OR, 94% are strongly acidic (below 5.5), 3% are near neutral (6.5-7.3), 3% are moderately acidic (5.5-6.5). Mapped soils run from pH 4 to 6.5, a spread of 2.5 units across 129 soil components. 94% 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 19.5% clay and 8.88% organic matter, which this site treats as clay. At 8.88% organic matter the soil buffers like a heavier one, which pushes it into the clay bracket. Moving it one pH unit takes about 11.5 lb of lime or 3.4 lb of sulfur per 100 sq ft. None of the mapped components carry free carbonate.

Clatsop against the rest of Oregon

pH 4.89 is 1.41 below the Oregon median of 6.3. 0 of 36 Oregon counties have more acidic topsoil. Nationally it is more acidic than the US county median of 6.05.

Closest in pH within the state: Lincoln (4.99), Tillamook (5), Coos (5.22), Curry (5.36).