Soil pH in San Miguel, CO: Lime or Sulfur?

Typical topsoil pH in San Miguel, CO

Typical topsoil in San Miguel, CO is pH 6.54, already right for vegetable garden (6-7). Test before adding anything.

What San Miguel needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, roses.
• Just outside, test first: strawberries (off by 0), pink hydrangeas (off by 0).
• Sulfur: potatoes 2.3 lb/100 sq ft over 2 applications; blueberries 3.5 lb/100 sq ft over 2 applications; azaleas and rhododendrons 3 lb/100 sq ft over 2 applications; blue hydrangeas 3 lb/100 sq ft over 2 applications.

What to do next

If your test lands near 6.54, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, tomatoes, strawberries, roses, pink hydrangeas.

How mixed the soil is

Of the 105,218 surveyed acres in San Miguel, CO, 53% are near neutral (6.5-7.3), 41% are moderately acidic (5.5-6.5), 5% are alkaline (above 7.3), 1% are strongly acidic (below 5.5). Mapped soils run from pH 5 to 8.2, a spread of 3.2 units across 138 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 22.4% clay and 2.14% 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. 1% of mapped components carry free carbonate (lime already in the ground).

San Miguel against the rest of Colorado

pH 6.54 is 0.63 below the Colorado median of 7.17. 8 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: Lake (6.37), Teller (6.41), Grand (6.42), Summit (6.42), Gunnison (6.6), Larimer (6.6), Jefferson (6.72), Boulder (6.75).

The range in Colorado runs from San Juan at 5.53 to Alamosa at 8.28; San Miguel sits 37% of the way up.