Soil pH in Fairbanks North Star Borough, AK: Lime or Sulfur?
Typical topsoil pH in Fairbanks North Star Borough, AK
Typical topsoil in Fairbanks North Star Borough, AK is pH 5.56, too acidic for vegetable garden. Expect roughly 6.3 lb of lime per 100 sq ft, but only after a soil test confirms it.
What Fairbanks North Star Borough needs, by plant
- Already in range: potatoes, strawberries, azaleas and rhododendrons.
- Just outside, test first: blueberries (off by 0.1), blue hydrangeas (off by 0.1).
- Lime: lawn (cool-season grass) 6.3 lb/100 sq ft over 2 applications; vegetable garden 6.3 lb/100 sq ft over 2 applications; tomatoes 6.3 lb/100 sq ft over 2 applications; roses 6.3 lb/100 sq ft over 2 applications; pink hydrangeas 4.9 lb/100 sq ft.
What to do next
If your test confirms pH near 5.56, spread about 63 lb of ground limestone per 1,000 sq ft of vegetable bed in 2 doses, ideally in fall.
How mixed the soil is
Of the 170,015 surveyed acres in Fairbanks North Star Borough, AK, 49% are moderately acidic (5.5-6.5), 46% are strongly acidic (below 5.5), 5% are near neutral (6.5-7.3). Mapped soils run from pH 4.8 to 7.4, a spread of 2.6 units across 404 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 7.7% clay and 6.16% organic matter, which this site treats as loam. At 6.16% organic matter the soil buffers like a heavier one, which pushes it into the loam bracket. Moving it one pH unit takes about 7 lb of lime or 2.3 lb of sulfur per 100 sq ft. None of the mapped components carry free carbonate.
Fairbanks North Star Borough against the rest of Alaska
pH 5.56 is 0.3 above the Alaska median of 5.26. 19 of 27 Alaska counties have more acidic topsoil. Nationally it is more acidic than the US county median of 6.05.
Closest in pH within the state: Petersburg Borough (5.3), Sitka Borough (5.3), Aleutians West Census Area (5.34), Nome Census Area (5.37), Bethel Census Area (5.57), North Slope Borough (5.62), Southeast Fairbanks Census Area (5.66), Yukon-Koyukuk Census Area (5.9).
The range in Alaska runs from Ketchikan Gateway Borough at 4.52 to Yakutat City and Borough at 6.08; Fairbanks North Star Borough sits 67% of the way up.