Answer: Soil pH is a measure of soil acidity. Soil pH affects a plant's ability to take up available nutrients. Modifying the pH of soil allows nutrients to be taken up by the plant. The ideal pH for most plants is between 6.0 and 6.8. Most soils in the Twin Cities area are alkaline (basic). Many evergreens, azaleas, rhododendrons and blueberries, however, benefit from acidic soil. Modifying the soil to a lower pH (more acidic) can create desirable color changes in Red Maple (Acer rubrum) and Bigleaf Hydrangea (Hydrangea macrophylla).
Acidic soils are soils that have a pH of less than 6.5. The most common cause of acidic soil is heavy rainfall. The rainfall dissolves mineral nutrients and leaches them from the soil. Acidic soils are found in Northern Minnesota and in coastal areas that have high evergreen tree populations (dead evergreen needles are acidic). Acidic soils are also found in areas where drainage is poor and there is standing water, such as a peat bog.
There are several ways to raise the pH of acidic soil. It will take one to two years for the soil pH to reflect the change.
To find out if your soil needs modification, you can have it tested, or you can purchase a testing kit. I personally would have it tested through the University of Minnesota. There is a fee, but not only will they test pH, but also minor and major elements. Along with the soil anaylsis, they'll include suggestions for changing the soil's pH if necessary.
A kit can be obtained directly from the Soil Testing Laboratory at 612-625-3101 or from your local County Extension Office. The laboratory can also be reached from the Yard and Garden Line at (612) 624-4771. Select #4 from the main voice mail menu.
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