Soil pH in Robertson, KY: Lime or Sulfur?

Typical topsoil pH in Robertson, KY

Typical topsoil in Robertson, KY is pH 6.18, already right for vegetable garden (6-7). Test before adding anything.

What Robertson needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, strawberries, roses, pink hydrangeas.
• Just outside, test first: tomatoes (off by 0), potatoes (off by 0.2), azaleas and rhododendrons (off by 0.2).
• Sulfur: blueberries 4.1 lb/100 sq ft over 3 applications; blue hydrangeas 3.1 lb/100 sq ft over 2 applications.

What to do next

If your test lands near 6.18, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, tomatoes, potatoes, strawberries, roses, azaleas and rhododendrons, pink hydrangeas.

How mixed the soil is

Of the 60,261 surveyed acres in Robertson, KY, 68% are moderately acidic (5.5-6.5), 25% are near neutral (6.5-7.3), 5% are alkaline (above 7.3), 3% are strongly acidic (below 5.5). Mapped soils run from pH 4.6 to 7.5, a spread of 2.9 units across 87 soil components. 68% 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 31.6% clay and 2.02% 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. 19% of mapped components carry free carbonate (lime already in the ground).

Robertson against the rest of Kentucky

pH 6.18 is 0.39 above the Kentucky median of 5.79. 97 of 120 Kentucky counties have more acidic topsoil. Nationally it is more alkaline than the US county median of 6.05.

Closest in pH within the state: Henderson (6.13), Shelby (6.13), Madison (6.14), Pendleton (6.14), Union (6.19), Boyle (6.21), Henry (6.21), Mason (6.25).

The range in Kentucky runs from Greenup at 5.09 to Carroll at 6.63; Robertson sits 71% of the way up.