I got a B&Q soil tester and it indicated the soil was about PH 9, dark green on the package scale indicator.

I only grow vegetables such as potatoes, onions, leeks, turnips and the like and I need to know how much sulphur per square yard or meter do I have to add to reduce the PH of the soil to get it slightly acidic which it seems is ideal for popular vegetables.

Can any one advise on the amount of sulphur to use please?

many thanks