Soil pH in Costilla, CO: Lime or Sulfur?

Typical topsoil pH in Costilla, CO

Typical topsoil in Costilla, CO is pH 7.19, just outside the 6-7 range for vegetable garden. Test first; it may need nothing.

What Costilla needs, by plant

• Just outside, test first: lawn (cool-season grass) (off by 0.2), vegetable garden (off by 0.2), roses (off by 0.2).
• Beds or pots instead: tomatoes, potatoes, strawberries, blueberries, azaleas and rhododendrons, blue hydrangeas, pink hydrangeas.

What to do next

If your test lands near 7.19, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, roses.

How mixed the soil is

Of the 618,615 surveyed acres in Costilla, CO, 58% are alkaline (above 7.3), 27% are near neutral (6.5-7.3), 13% are moderately acidic (5.5-6.5), 2% are strongly acidic (below 5.5). Mapped soils run from pH 4.8 to 9.4, a spread of 4.6 units across 90 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 12.3% clay and 1.48% 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. 37% of mapped components carry free carbonate (lime already in the ground), enough that sulfur gets neutralised before it does much.

Costilla against the rest of Colorado

pH 7.19 is right at the Colorado median of 7.17. 33 of 63 Colorado counties have more acidic topsoil. Nationally it is more alkaline than the US county median of 6.05.

Closest in pH within the state: Chaffee (7.16), Phillips (7.17), Sedgwick (7.17), Huerfano (7.18), Logan (7.2), Arapahoe (7.22), Denver (7.24), Adams (7.25).

The range in Colorado runs from San Juan at 5.53 to Alamosa at 8.28; Costilla sits 60% of the way up.