Plant World

Soil, Gardening, and Farming

What does “pH” mean when applied to soil?

Literally, pH stands for “potential of hydrogen” and is the term used by soil scientists to represent the hydrogen ion concentration in a soil sample. The relative alkalinity-acidity is commonly expressed in terms of the symbol pH. The neutral point in the scale is 7: soil testing below 7 is said to be acidic; soil testing above pH 7 is alkaline. The pH values are based on logarithms with a base of ten. Thus, a soil testing pH 5 is ten times as acidic as soil testing pH 5; while a soil testing pH 4 is one hundred times as acidic as soil testing pH 6.


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