Soil pH in San Joaquin, CA: Lime or Sulfur?

Typical topsoil pH in San Joaquin, CA

Typical topsoil in San Joaquin, CA is pH 6.81, already right for vegetable garden (6-7). Test before adding anything.

What San Joaquin needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, roses.
• Just outside, test first: tomatoes (off by 0).
• Sulfur: potatoes 3 lb/100 sq ft over 2 applications; strawberries 1.8 lb/100 sq ft; blueberries 4.1 lb/100 sq ft over 3 applications; azaleas and rhododendrons 3.7 lb/100 sq ft over 2 applications; blue hydrangeas 3.7 lb/100 sq ft over 2 applications; pink hydrangeas 1.4 lb/100 sq ft.

What to do next

If your test lands near 6.81, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, tomatoes, roses.

How mixed the soil is

Of the 744,727 surveyed acres in San Joaquin, CA, 42% are near neutral (6.5-7.3), 32% are moderately acidic (5.5-6.5), 25% are alkaline (above 7.3). Mapped soils run from pH 4.8 to 8.7, a spread of 3.9 units across 280 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 26% clay and 2.69% 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. 17% of mapped components carry free carbonate (lime already in the ground).

San Joaquin against the rest of California

pH 6.81 is 0.27 above the California median of 6.54. 39 of 58 California counties have more acidic topsoil. Nationally it is more alkaline than the US county median of 6.05.

Closest in pH within the state: Lassen (6.77), Mono (6.79), Alameda (6.81), Monterey (6.81), Colusa (6.89), Yolo (6.9), Stanislaus (6.96), Modoc (7.04).

The range in California runs from Del Norte at 5.43 to Imperial at 8.16; San Joaquin sits 51% of the way up.