Soil pH in Southeast Fairbanks Census Area, AK: Lime or Sulfur?
Typical topsoil pH in Southeast Fairbanks Census Area, AK
Typical topsoil in Southeast Fairbanks Census Area, AK is pH 5.66, too acidic for vegetable garden. Expect roughly 5.6 lb of lime per 100 sq ft, but only after a soil test confirms it.
What Southeast Fairbanks Census Area needs, by plant
- Already in range: potatoes, strawberries, azaleas and rhododendrons.
- Just outside, test first: blueberries (off by 0.2), blue hydrangeas (off by 0.2).
- Lime: lawn (cool-season grass) 5.6 lb/100 sq ft over 2 applications; vegetable garden 5.6 lb/100 sq ft over 2 applications; tomatoes 5.6 lb/100 sq ft over 2 applications; roses 5.6 lb/100 sq ft over 2 applications; pink hydrangeas 4.2 lb/100 sq ft.
What to do next
If your test confirms pH near 5.66, spread about 56 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 520,650 surveyed acres in Southeast Fairbanks Census Area, AK, 71% are moderately acidic (5.5-6.5), 25% are strongly acidic (below 5.5), 3% are near neutral (6.5-7.3). Mapped soils run from pH 4.2 to 7.4, a spread of 3.2 units across 507 soil components. 71% 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 6.5% clay and 11.85% organic matter, which this site treats as loam. At 11.85% 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.
Southeast Fairbanks Census Area against the rest of Alaska
pH 5.66 is 0.4 above the Alaska median of 5.26. 22 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: Nome Census Area (5.37), Fairbanks North Star Borough (5.56), Bethel Census Area (5.57), North Slope Borough (5.62), Yukon-Koyukuk Census Area (5.9), Denali Borough (5.94), Hoonah-Angoon Census Area (6.06), Yakutat City and Borough (6.08).
The range in Alaska runs from Ketchikan Gateway Borough at 4.52 to Yakutat City and Borough at 6.08; Southeast Fairbanks Census Area sits 73% of the way up.