How can acidity in soil be increased?
Clay, sandy loam
I think you're asking about decreasing pH. Using pH is a much sounder way of thinking of soil acidity since there is a concrete scale to guide decisions. Step one is to test your soil to determine what the pH is. Without this information, you'll have no idea how much acidifier to add. You'll need to monitor the pH on an every year or two basis because changing soil pH is not a "one and done" task. There are several products you can use but follow instructions carefully. It is possible to burn plant roots if too much is applied at one time. Here is an article that discusses different forms of sulfur and how much is needed. https://hort.uwex.edu/articles/reducing-soil-ph/. Check your own state's extension service for information that addresses the soils in your area.