Soil pH Testing and Management

Listed in Table 2 are soil pH classes. Since soluble salts affect soil pH and vice versa, pH is often included in evaluations and discussions of soil saltiness. Changing the soil pH often results in a corresponding change in plant nutrient availability. The availability of certain nutrients in soil solution begins to decrease above pH ~5.5 (iron [Fe], manganese [Mn], zinc [Zn], copper [Cu], cobalt [Co]), above ~7.0 (phosphorus [P], boron [B]), and above 8.5 (calcium [Ca], magnesium [Mg]). The soil pH scale ranges from 0 to 14, with <7 considered acidic, 7 neutral, and >7 alkaline or basic. Most arable soils in our region have a pH in the range of 7 to 9. Soil pH measuring 6.1 to 7.0 is considered ideal for most trees and shrubs, although various species will grow in a range from 5.5 to 8.0+.

It is more likely that a naturally salt-affected soil will have a high, rather than low, soil pH. Reducing high soil pH is typically accomplished by applying acidifying fertilizers (such as ammonium sulfate, ammonium phosphate-sulfate, etc.,) to the soil, often in conjunction with soil applied chelated iron and manganese if inter-veinal chlorosis is noted.

Iron Chlorosis in Amur Maple Caused by High Soil pH

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Last Modified: 10/10/2007