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Name: Virginia
Status: Student
Grade: 9-12
Location: MA
Country: United States
Date: November 2006


Question:
What is soil PH? Is it better for the ph to be high or low.



Replies:
pH is a measure of soil acidity. Low pH soils are acid and high pH soils are basic. Soils east of the Mississippi river tend to be acid while those to the west tend to be basic. The pH controls what minerals are available for plant growth. Basic soils, for example have less iron available. Wild plants have adapted to varying soil pH as a way of minimizing competition.

For the gardener, soil pH is of great concern depending upon what they are trying to grow. I have often added ground lime to soils to make them more basic, or "chelated sulfur" to turn them more acid. Of course, I move around a lot, too.

R. Avakian


The pH is the logarithm of 1/[H+] where [H+] is the concentration of hydrogen ions. So it is a measure of how acidic or basic a solution is. Low values: 0 to 7 are acidic. High values 7 to 14 are alkaline. With regard to which is "better" depends upon what the soil is intended to do. Some plants grow better in somewhat alkaline conditions. Other plants grow better in somewhat acidic conditions. So there is no universal "good" or "bad". It depends upon what the use of the soil is.

Vince Calder



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