Soil pH in Jefferson, LA: Lime or Sulfur?

Typical topsoil pH in Jefferson, LA

Typical topsoil in Jefferson, LA is pH 6.36, already right for vegetable garden (6-7). Test before adding anything.

What Jefferson needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, strawberries, roses, pink hydrangeas.
• Sulfur: potatoes 3.1 lb/100 sq ft over 2 applications; blueberries 4.8 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.

What to do next

If your test lands near 6.36, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, tomatoes, strawberries, roses, pink hydrangeas.

How mixed the soil is

Of the 152,040 surveyed acres in Jefferson, LA, 47% are near neutral (6.5-7.3), 45% are moderately acidic (5.5-6.5), 7% are strongly acidic (below 5.5), 1% are alkaline (above 7.3). Mapped soils run from pH 5.1 to 7.5, a spread of 2.4 units across 49 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 61.4% clay and 5.7% organic matter, which this site treats as clay. At 5.7% 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. 6% of mapped components carry free carbonate (lime already in the ground).

Jefferson against the rest of Louisiana

pH 6.36 is 0.82 above the Louisiana median of 5.54. 48 of 64 Louisiana counties have more acidic topsoil. Nationally it is more alkaline than the US county median of 6.05.

Closest in pH within the state: Cameron (6.16), St. Landry (6.16), Lafourche (6.28), St. Martin (6.33), Iberville (6.38), Terrebonne (6.41), Ascension (6.44), Assumption (6.44).

The range in Louisiana runs from Allen at 4.88 to St. Bernard at 7; Jefferson sits 70% of the way up.