Soil pH in Kenai Peninsula Borough, AK: Lime or Sulfur?

Typical topsoil pH in Kenai Peninsula Borough, AK

Typical topsoil in Kenai Peninsula Borough, AK is pH 4.85, too acidic for vegetable garden. Expect roughly 11.9 lb of lime per 100 sq ft, but only after a soil test confirms it.

What Kenai Peninsula Borough needs, by plant

• Already in range: blueberries, azaleas and rhododendrons.
• Just outside, test first: potatoes (off by 0.2), blue hydrangeas (off by 0.2).
• Lime: lawn (cool-season grass) 11.9 lb/100 sq ft over 3 applications; vegetable garden 11.9 lb/100 sq ft over 3 applications; tomatoes 11.9 lb/100 sq ft over 3 applications; strawberries 8.4 lb/100 sq ft over 2 applications; roses 11.9 lb/100 sq ft over 3 applications; pink hydrangeas 9.8 lb/100 sq ft over 2 applications.

What to do next

If your test confirms pH near 4.85, spread about 119 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 698,509 surveyed acres in Kenai Peninsula Borough, AK, 94% are strongly acidic (below 5.5), 4% are moderately acidic (5.5-6.5), 1% are near neutral (6.5-7.3), 1% are alkaline (above 7.3). Mapped soils run from pH 3.7 to 8.2, a spread of 4.5 units across 568 soil components. 94% 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 7.2% clay and 6.5% organic matter, which this site treats as loam. At 6.5% 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. 0% of mapped components carry free carbonate (lime already in the ground).

Kenai Peninsula Borough against the rest of Alaska

pH 4.85 is 0.41 below the Alaska median of 5.26. 3 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: Ketchikan Gateway Borough (4.52), Lake and Peninsula Borough (4.83), Skagway Borough (4.84), Anchorage Borough (4.89), Dillingham Census Area (4.94), Wrangell-Petersburg Census Area (4.94), Kodiak Island Borough (4.96).

The range in Alaska runs from Ketchikan Gateway Borough at 4.52 to Yakutat City and Borough at 6.08; Kenai Peninsula Borough sits 21% of the way up.