Soil pH in Rockwall, TX: Lime or Sulfur?

Typical topsoil pH in Rockwall, TX

Typical topsoil in Rockwall, TX is pH 7.77 and calcareous, so sulfur won't lower it for long. For vegetable garden, choose alkaline-tolerant varieties and add compost rather than fighting the soil.

What Rockwall needs, by plant

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

What to do next

If your test confirms pH near 7.77, consider raised beds for anything acid-loving; with 81% of soils here carrying free lime, sulfur will not hold.

How mixed the soil is

Of the 68,398 surveyed acres in Rockwall, TX, 81% are alkaline (above 7.3), 19% are near neutral (6.5-7.3). Mapped soils run from pH 6.5 to 8.2, a spread of 1.7 units across 26 soil components. 81% 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 50.7% clay and 2.4% organic matter, which this site treats as clay. Moving it one pH unit takes about 11.5 lb of lime or 3.4 lb of sulfur per 100 sq ft. 81% of mapped components carry free carbonate (lime already in the ground), enough that sulfur gets neutralised before it does much.

Rockwall against the rest of Texas

pH 7.77 is 0.34 above the Texas median of 7.43. 208 of 254 Texas counties have more acidic topsoil. Nationally it is more alkaline than the US county median of 6.05.

Closest in pH within the state: Presidio (7.76), Sutton (7.76), Throckmorton (7.76), Howard (7.77), Terry (7.77), King (7.78), Kendall (7.79), Potter (7.79).

The range in Texas runs from Hardin at 4.64 to Upton at 8.19; Rockwall sits 88% of the way up.