Soil pH in Del Norte, CA: Lime or Sulfur?

Typical topsoil pH in Del Norte, CA

Typical topsoil in Del Norte, CA is pH 5.43, too acidic for vegetable garden. Expect roughly 12.7 lb of lime per 100 sq ft, but only after a soil test confirms it.

What Del Norte needs, by plant

• Already in range: potatoes, blueberries, azaleas and rhododendrons, blue hydrangeas.
• Just outside, test first: strawberries (off by 0.1).
• Lime: lawn (cool-season grass) 12.7 lb/100 sq ft over 3 applications; vegetable garden 12.7 lb/100 sq ft over 3 applications; tomatoes 12.7 lb/100 sq ft over 3 applications; roses 12.7 lb/100 sq ft over 3 applications; pink hydrangeas 9.2 lb/100 sq ft over 2 applications.

What to do next

If your test confirms pH near 5.43, spread about 127 lb of ground limestone per 1,000 sq ft of vegetable bed in 3 doses, ideally in fall.

How mixed the soil is

Of the 111,331 surveyed acres in Del Norte, CA, 69% are strongly acidic (below 5.5), 24% are moderately acidic (5.5-6.5), 6% are near neutral (6.5-7.3), 1% are alkaline (above 7.3). Mapped soils run from pH 4.3 to 8.2, a spread of 3.9 units across 405 soil components. 69% 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 22% clay and 5.85% organic matter, which this site treats as clay. At 5.85% 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.

Del Norte against the rest of California

pH 5.43 is 1.11 below the California median of 6.54. 0 of 58 California counties have more acidic topsoil. Nationally it is more acidic than the US county median of 6.05.

Closest in pH within the state: Humboldt (5.75), Mariposa (5.87), Amador (6), Tuolumne (6.02).