Soil pH in St. James, LA: Lime or Sulfur?

Typical topsoil pH in St. James, LA

Typical topsoil in St. James, LA is pH 6.76, already right for vegetable garden (6-7). Test before adding anything.

What St. James needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, roses.
• Beds or pots instead: potatoes, strawberries, blueberries, azaleas and rhododendrons, blue hydrangeas, pink hydrangeas.

What to do next

If your test lands near 6.76, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, tomatoes, roses.

How mixed the soil is

Of the 148,407 surveyed acres in St. James, LA, 79% are near neutral (6.5-7.3), 16% are moderately acidic (5.5-6.5), 5% are alkaline (above 7.3). Mapped soils run from pH 5.7 to 8.2, a spread of 2.5 units across 32 soil components. 79% 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 60% clay and 6.8% organic matter, which this site treats as clay. At 6.8% 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. 43% of mapped components carry free carbonate (lime already in the ground), enough that sulfur gets neutralised before it does much.

St. James against the rest of Louisiana

pH 6.76 is 1.22 above the Louisiana median of 5.54. 59 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: St. Mary (6.52), St. Charles (6.53), Orleans (6.61), Plaquemines (6.71), St. John the Baptist (6.78), Pointe Coupee (6.84), West Baton Rouge (6.9), St. Bernard (7).

The range in Louisiana runs from Allen at 4.88 to St. Bernard at 7; St. James sits 89% of the way up.