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How to Acidify Soils

By G.K. Bayne ; Updated September 21, 2017
Plants such as a blueberry require an acidic soil.
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Many plants require acidic soils to thrive. Soils with a pH level of 5.5 and below are acidic. According to the Michigan extension service, when lowering soil pH levels it is highly recommended to perform a soil test. There are soil test kits available that will check the pH level of the dissolved soil. Distilled water must be used in this type of test, as the pH level of the water must be neutral. If you are unsure of conducting such a test, consult your local agricultural extension service for soil test services in your area.

Conduct a soil test for identifying the pH level of the soil. Correlate the pH level required for the plant species you are wanting to place in the ground. In other words, the soil test result may show a pH level of 6.0 and the plant species may require a pH level of 5.0. You can use the elemental sulfur chart in the Resource section below as a base reference.

Add 1.6 pounds of elemental sulfur per 100 square feet of loamy soil. Different soil types will require various amounts of elemental sulfur. While adding elemental sulfur may take some time to fully take effect, it will last up to five years, according to the Ohio State extension service. Work the material into the soil using a mechanical rototiller or hand cultivator.

Work iron sulfate into the soil with mechanical or hand cultivation if a faster reaction time is desired. Michigan State University advises not to add more than 9 pounds of the iron sulfate per 100 square feet of area. If more is required through testing, extend the addition over a 1-month to 2-month time frame. Iron sulfate will tend to react with soils in a 3-week to 4-week period.

Use acid sphagnum peat when first transplanting acid loving trees and bushes into the soil. The peat can be worked into the transplant hole and will aid in breaking up heavy soils. Incorporate peat in equal parts with the native soil. You can add 1 cubic foot to 2 cubic feet per plant per transplant hole. The effects of the acid peat will last 6 to 10 years. After that time frame, the pH level will tend to increase and other acid treatments will be necessary.


Things You Will Need

  • Soil pH level test results
  • Elemental sulfur (optional)
  • Rototiller
  • Hand cultivator
  • Iron sulfate (optional)
  • Acid sphagnum peat (optional)


  • Ammonium sulfate or urea, which is a high-nitrogen fertilizer, can raise the acid level of the soils. Caution must be exercised when using a nitrogen-based acid fertilizer, as the nitrogen levels can exceed your plants' optimum growing conditions.
  • It is best to add a little of the acid chemical at a time, then retest the soil on a periodic basis. Adding too much chemical may harm other plants in the soil's water runoff area.