How much Sulfur vs Iron Sulfate to use to reduce soil PH - Ask Extension
I see on this page https://extension.umd.edu/resource/growing-blueberries-home-garden/ , there is a table regarding how much sulfur and iron sulfate t...
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How much Sulfur vs Iron Sulfate to use to reduce soil PH #862775
Asked March 28, 2024, 9:22 PM EDT
I see on this page https://extension.umd.edu/resource/growing-blueberries-home-garden/ , there is a table regarding how much sulfur and iron sulfate to use in order to reduce soil PH to 4.5. My question is whether that table is saying to use X amount of sulfur AND X amount of iron sulfate, or if I should just use one or the other. My assumption is that I use both. So if I have loamy/clay soil that is currently at 6.5, I would want to use 2.3lbs of sulfur AND 8lbs of iron sulfate.
Anne Arundel County Maryland
Expert Response
We are in the midst of revising our blueberry page and the new version will be published soon (hopefully in a couple weeks or less), but the current table is an either-or presentation; it mentions in that section "...pounds of sulfur or iron sulfate..." since either by itself will suffice. However, if you already purchased sulfur and iron sulfate, you can use them together to effectively lower the soil pH to 4.5, but would have to reduce the amount of each compared to what is recommended in the table so it isn't over-applied.
If you have not purchased iron sulfate, you only need to use powdered sulfur (sold also as "elemental sulfur," "micronized sulfur," or "flowers of sulfur"). Using the information in the linked page below, you would apply and incorporate the calculated amount based on your soil type (loamy, clay-based, etc.).
Clemson’s Soil Acidification Calculator is a tool you can use to determine how much sulfur to apply to lower pH from your current level, if needed. Application rates are provided for elemental sulfur and aluminum sulfate, since either can be used (by itself) when lowering pH for various situations. That said, do not use aluminum sulfate for blueberries because they are sensitive to excess aluminum. (It’s okay to apply the total amount of sulfur in two or more applications instead of all at once, if you want.)
Miri
If you have not purchased iron sulfate, you only need to use powdered sulfur (sold also as "elemental sulfur," "micronized sulfur," or "flowers of sulfur"). Using the information in the linked page below, you would apply and incorporate the calculated amount based on your soil type (loamy, clay-based, etc.).
Clemson’s Soil Acidification Calculator is a tool you can use to determine how much sulfur to apply to lower pH from your current level, if needed. Application rates are provided for elemental sulfur and aluminum sulfate, since either can be used (by itself) when lowering pH for various situations. That said, do not use aluminum sulfate for blueberries because they are sensitive to excess aluminum. (It’s okay to apply the total amount of sulfur in two or more applications instead of all at once, if you want.)
Miri
