Is your soil pH too high or too low? If you don’t know the answer, I urge you to get a soil test. Only a soil test can indicate whether the pH is accurate, and the right level really depends on the plant you want to grow and the natural pH of your soil. Fruits and vegetables accept a wide range of soil pH levels, and acidifying soil is generally unnecessary and not recommended. However, certain fruits, rhododendrons, and azaleas can be intolerant to alkaline soil conditions. The soil pH must be maintained at 5.5 or less for these to grow successfully.

To determine the current soil pH, start with a soil test.

For soils having a pH of less than 6.5, you should be able to add a soil amendment (e.g., some form of sulfur) and successfully lower pH, if needed, based on your crop. Soil pH can be reduced most effectively by adding elemental sulfur, aluminum sulfate, or sulfuric acid.

Soil pH can be raised using pulverized lime. Hydrated lime should only be used with highly acidic soils since it is more water-soluble and can quickly increase a soil’s pH.

Micronutrients in your soil like dolomite, a mixture of calcium and magnesium carbonates. These are great options if your soil is also missing some key nutrients.

An imbalance of soil pH can exacerbate weed problems

The easiest way to manage soil pH is to be careful what you put into it in the first place.

  • Know the pH requirements of your plant before you plant them.
  • Lime to raise the pH of acid soil when necessary and apply nitrogen and sulfur according to crop needs.
  • Apply nitrogen fertilizer in proper amounts promptly (relative to crop needs), and use good irrigation management to minimize nitrate leaching.
  • Practice crop rotation to interrupt acidifying effects from nitrogen fertilizer application.
  • Apply irrigation water, manure, and other organic materials that have a high content of calcium or magnesium can all help keep your soil in balance from one season to the next.

Need further information or guidance? 

About the Author

Marcus Williams is CFSA’s farm services director, which oversees CFSA’s Farm Services technical assistance programs—including organic production and certification, high tunnel production, research, and conservation planning—and growing the organic research program at CFSA’s research and education farm in Concord, North Carolina.