Soil pH problems

By The Old House Web

Soil pH problems

Soil pH determines the availability of the nutrients in the soil solution. Some plants, such as rhododendron or azalea, have difficulty absorbing iron unless the soil pH is between 4.5 and 5.5. Pin oak and holly will show iron deficiency symptoms at a pH above 7.5. On maples, manganese deficiency is more common than iron deficiency.

Correcting a high soil pH over the entire area of a tree's root zone may not be worth the effort. Maintaining a low pH for a small number of shrubs is more feasible.

Lower the pH by applying sulfur. Use Table 1 as a guide for sulfur rates. You need to know the existing pH and the soil type to use the table properly.

Quantity of sulfur required to reduce soil pH for a depth of 7 inches. ------------------------------------------------------------ Desired pH Sands Sandy Loams Loams Clay Loams Organic Change ------------lb sulfur/100 square feet-----------

7.0-6.0 0.7 1.2 1.6 2.5 3.9 6.0-5.0 1.8 2.8 3.2 3.2 6.3 5.0-4.0 1.8 2.8 3.2 4.1 10.3 ------------------------------------------------------------ Avoid sulfur applications to lawns during hot weather to minimize the possibility of burning the grass.

Other materials, such as aluminum sulfate, are also used to reduce soil pH, but more of the alternative materials is needed to obtain the same change in pH.

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