Soil pH in Petersburg Borough, AK: Lime or Sulfur?
Typical topsoil pH in Petersburg Borough, AK
Typical topsoil in Petersburg Borough, AK is pH 5.3, too acidic for vegetable garden. Expect roughly 13.8 lb of lime per 100 sq ft, but only after a soil test confirms it.
What Petersburg Borough needs, by plant
- Already in range: potatoes, blueberries, azaleas and rhododendrons, blue hydrangeas.
- Just outside, test first: strawberries (off by 0.2).
- Lime: lawn (cool-season grass) 13.8 lb/100 sq ft over 3 applications; vegetable garden 13.8 lb/100 sq ft over 3 applications; tomatoes 13.8 lb/100 sq ft over 3 applications; roses 13.8 lb/100 sq ft over 3 applications; pink hydrangeas 11.5 lb/100 sq ft over 3 applications.
What to do next
If your test confirms pH near 5.3, spread about 138 lb of ground limestone per 1,000 sq ft of vegetable bed in 3 doses, ideally in fall.
How mixed the soil is
Of the 2,577 surveyed acres in Petersburg Borough, AK, 100% are strongly acidic (below 5.5). Mapped soils run from pH 5.3 to 5.3, a spread of 0 units across 1 soil components. 100% 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 7.5% organic matter, which this site treats as clay. At 7.5% organic matter the soil buffers like a heavier one, which pushes it into the clay bracket. Moving it one pH unit takes about 11.5 lb of lime or 3.4 lb of sulfur per 100 sq ft. None of the mapped components carry free carbonate.
Petersburg Borough against the rest of Alaska
pH 5.3 is right at the Alaska median of 5.26. 14 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: Matanuska-Susitna Borough (5.2), Northwest Arctic Borough (5.23), Kusilvak Census Area (5.26), Juneau Borough (5.3), Sitka Borough (5.3), Aleutians West Census Area (5.34), Nome Census Area (5.37), Fairbanks North Star Borough (5.56).
The range in Alaska runs from Ketchikan Gateway Borough at 4.52 to Yakutat City and Borough at 6.08; Petersburg Borough sits 50% of the way up.