Increments between each number represent a tenfold increase. For example, at pH 5 it is 10 times more acidic than at pH 6. Soil pH of 6.0 to 7.0 is suitable for most plant growth. A soil test is necessary to determine pH of soil. Gardeners should know the pH of their soil because it affects the availability of plant nutrients.
Nutrients become less available at pH extremes.
The pH of soil is usually correct for most plants. 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.