Soil pH in Morrow, OR: Lime or Sulfur?

Typical topsoil pH in Morrow, OR

Typical topsoil in Morrow, OR is pH 7.04, just outside the 6-7 range for vegetable garden. Test first; it may need nothing.

What Morrow needs, by plant

• Just outside, test first: lawn (cool-season grass) (off by 0), vegetable garden (off by 0), tomatoes (off by 0.2), roses (off by 0).
• Sulfur: potatoes 3.5 lb/100 sq ft over 2 applications; strawberries 2.3 lb/100 sq ft over 2 applications; blueberries 4.6 lb/100 sq ft over 3 applications; azaleas and rhododendrons 4.1 lb/100 sq ft over 3 applications; blue hydrangeas 4.1 lb/100 sq ft over 3 applications; pink hydrangeas 1.8 lb/100 sq ft.

What to do next

If your test lands near 7.04, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, tomatoes, roses.

How mixed the soil is

Of the 897,604 surveyed acres in Morrow, OR, 84% are near neutral (6.5-7.3), 8% are moderately acidic (5.5-6.5), 7% are alkaline (above 7.3). Mapped soils run from pH 6.3 to 9, a spread of 2.7 units across 148 soil components. 84% 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 13.1% clay and 1.64% 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. None of the mapped components carry free carbonate.

Morrow against the rest of Oregon

pH 7.04 is 0.74 above the Oregon median of 6.3. 31 of 36 Oregon counties have more acidic topsoil. Nationally it is more alkaline than the US county median of 6.05.

Closest in pH within the state: Union (6.89), Sherman (6.94), Umatilla (6.96), Gilliam (6.99), Baker (7.1), Lake (7.46), Harney (7.47), Malheur (7.9).

The range in Oregon runs from Clatsop at 4.89 to Malheur at 7.9; Morrow sits 71% of the way up.