However, most soils in Ohio must be modified for acid-loving evergreens. Use of commercial fertilizer can cause soil to become more acidic, resulting in the need to add lime. Lime is applied to make the soil more alkaline. Ground agricultural limestone is an inexpensive soil amendment. Lime is safe to use, nontoxic to humans and does not cause pollution problems.
Dolomitic lime offers the added benefit of magnesium.
Wood ashes can raise pH, but are not recommended. There is no way to determine accurately the volume to add for the desired change. They are very messy and leach out of the soil so rapidly that they are ineffective. If pH is too alkaline, add sulfur to lower the pH. Chelated iron sulfate or aluminum sulfate has an acid reaction and is commonly added to correct chlorosis or yellowing of leaves. Overly alkaline soil interferes with plant uptake of iron.