Ginseng: Changing Soil pH

I would like to know what to use to increase or decrease the pH level of the soil ? Will this cause a mineral ring to show in the root if used on older plants ?

Use flower of sulphur or ferrous sulphate to lower the pH and lime to raise it. The flower of sulphur will take longer to lower the pH but will also last longer than the ferrous sulphate.
I have not heard of these chemicals causing a mineral ring in the finished product, but that may be because all instructions always advise to change the soil pH well before sowing the seeds.