Soil pH in Colorado, TX: Lime or Sulfur?

Typical topsoil pH in Colorado, TX

Typical topsoil in Colorado, TX is pH 6.01, already right for vegetable garden (6-7). Test before adding anything.

What Colorado needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, strawberries, roses, pink hydrangeas.
• Just outside, test first: tomatoes (off by 0.2), potatoes (off by 0), azaleas and rhododendrons (off by 0).
• Sulfur: blueberries 2.3 lb/100 sq ft over 2 applications; blue hydrangeas 1.8 lb/100 sq ft.

What to do next

If your test lands near 6.01, 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 548,473 surveyed acres in Colorado, TX, 40% are moderately acidic (5.5-6.5), 33% are strongly acidic (below 5.5), 14% are alkaline (above 7.3), 13% are near neutral (6.5-7.3). Mapped soils run from pH 4.5 to 8.2, a spread of 3.7 units across 105 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 14.7% clay and 1.23% 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).

Colorado against the rest of Texas

pH 6.01 is 1.42 below the Texas median of 7.43. 35 of 254 Texas counties have more acidic topsoil. Nationally it is more acidic than the US county median of 6.05.

Closest in pH within the state: Walker (5.79), Anderson (5.87), Chambers (5.89), Van Zandt (5.91), Madison (6.02), Franklin (6.04), Harris (6.04), Leon (6.04).

The range in Texas runs from Hardin at 4.64 to Upton at 8.19; Colorado sits 39% of the way up.