how much 90% sulfur do you need to drop ph from 7.5 to 6.5 to 5.5 and so on for blueberries
There isn't a specific formulation or amount to use for exact ph adjustments. But if you look at the label for our SULFUR GRANULES, you'll see it says to use about 3.5 lbs per 1000 sq/ft. Exactly how much this will reduce the PH is hard to guage but in most situations it will be around .5-1.0 of a drop. So start with this rate and monitor the PH using a PH METER. Once you see the PH has dropped and becomes stable, apply some more. As you approach your goal, reduce the amount of Sulfur you're applying to maybe 1-2 lbs per treatment instead of the full 3.5 lbs. Over the course of 3-6 months you should be able to get it adjusted to where you want it to be.
Here are direct links to the information and products listed above:
Sulfur Granules: http://www.non-toxic-pest-control.com/granules/sulfur-90-granules