Soil pH in Los Alamos, NM: Lime or Sulfur?

Typical topsoil pH in Los Alamos, NM

Typical topsoil in Los Alamos, NM is pH 7.02, just outside the 6-7 range for vegetable garden. Test first; it may need nothing.

What Los Alamos needs, by plant

• Just outside, test first: lawn (cool-season grass) (off by 0), vegetable garden (off by 0), tomatoes (off by 0.2), roses (off by 0).
• Sulfur: potatoes 3.5 lb/100 sq ft over 2 applications; strawberries 2.3 lb/100 sq ft over 2 applications; blueberries 4.6 lb/100 sq ft over 3 applications; azaleas and rhododendrons 4.1 lb/100 sq ft over 3 applications; blue hydrangeas 4.1 lb/100 sq ft over 3 applications; pink hydrangeas 1.8 lb/100 sq ft.

What to do next

If your test lands near 7.02, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, tomatoes, roses.

How mixed the soil is

Of the 17,722 surveyed acres in Los Alamos, NM, 82% are near neutral (6.5-7.3), 11% are alkaline (above 7.3), 7% are moderately acidic (5.5-6.5). Mapped soils run from pH 6.1 to 8.1, a spread of 2 units across 51 soil components. 82% 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 15% 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. 13% of mapped components carry free carbonate (lime already in the ground).

Los Alamos against the rest of New Mexico

pH 7.02 is 0.63 below the New Mexico median of 7.65. 1 of 33 New Mexico counties have more acidic topsoil. Nationally it is more alkaline than the US county median of 6.05.

Closest in pH within the state: Colfax (6.99), Taos (7.04), Rio Arriba (7.23), Mora (7.25), Catron (7.26).

The range in New Mexico runs from Colfax at 6.99 to Valencia at 8.07; Los Alamos sits 3% of the way up.