What products can I use to lower the soil pH around my blueberries?

Gardens & Landscapes April 09, 2008|Print
Blueberries thrive in a highly organic, well-drained soil with a pH of 4.5 to 5.2. Most soils can be amended with finely ground sulfur (garden sulfur) or aluminum sulfate to adjust pH to optimum levels. It is important to amend the soil with peat moss and then take a soil test to determine nutrient levels and soil pH. This test can be performed at your local Extension office for a nominal fee. Soils with an available calcium level below 2,500 pounds per acre can usually be effectively acidified. Refer to the table below for the quantity of sulfur needed to adjust soil pH. Sulfur or aluminum sulfate should be tilled into the soil at least 60 days before planting. Retest the soil pH 60 to 90 days after applying sulfur to determine if you need another application. Continue to test the soil for the next several years to make sure that the pH remains in the 4.5 to 5.2 range. On some soils and in instances where the irrigation water pH is high, the soil pH will tend to increase with time.
Table 1. Amending soil to reduce pH.
To lower the pH one full pH unit (e.g., from 5.5 to 4.5), incorporate either finely ground sulfur or aluminum sulfate. Sulfur is usually the least expensive material. Use the water pH value rather than the buffer pH value to determine how much sulfur or aluminum sulfate to incorporate.

Soil Texture

Sulfur lb/100 sq ft1

Aluminum Sulfate lb/100 sq ft1

Light, Sandy

0.75

4.5

Medium, Sandy Loam

1.50

9.0

Heavy, Clay Loam

2.25

13.5

1 Because the soil's buffering capacity affects the degree to which a soil is acidified, apply the recommended amount well before planting. Then recheck the pH 60 to 90 days later.