Hey Darrin based on my Midwest labs test and my M3 test from Logan I would say sulfur is part of organic matter not just attached to it. As I said the one test shows 400ppm and the M3 shows 15ppm in a 7% organic matter soil with a sandy base. The same total test shows I have 1100ppm of nitrogen which must also be in the organic matter not just attached. I don’t know where else these two minerals would be in this quantity unless it was actually part of the OM itself. I could be wrong but that’s what I concluded.