Brambles Require a pH of 6.0-6.8

The new brambles I planted are thriving despite the pH level of the soil being too alkaline. The soil is supposed to be between 6.0 and 6.8, so I need to add sulfur, which will make the soil more acidic. If I wanted to make it even more alkaline, I'd add lime.

pH is a measure of the soil acidity or alkalinity
How do I make the soil more acidic? Here are 6 ways:

1. sphagnum peat
2. elemental sulfur
3. aluminum sulfate
4. iron sulfate
5. acidifying nitrogen
6. organic mulch

I don't know what I'll do yet, but I'll make sure to post about it.