Sulphate is great at turning things acidic, but it is very very hard to put on.

Naturally soil contains clay minerals, to which magnesium, phosphorous, nitrogen, and calcium ions are bound (amongst others). To get at these essential plant nutrients, plant roots actively pump hydrogen ions into the surrounding soil. When a hydrogen ions comes into contact with the natural minerals, they break the bond to the clay, freeing magnesium etc, to be taken up by the plant. Because the hydrogen ion has a higher afinity for the clay, it can stay there for a long time. The problem comes when you try to introduce hydrogen ions: they release all the nutrients locked in the soil at once. This is grand for a couple of months, but after which, all the valuable plant nutrients in the soil get washed down into the water table. This leaves the plant even more starved!

The way to do it is to mulch with organic matter, to gradually acidify the soil by natural nitrification. Don't get me wrong, you can achieve the right results with sulphur, but you need to analyse the soil first to calclate the right dose. Getting it a gram wrong could blow things out!