Sulfur is an essetial ingredient in what gives alliums their flavor. You get bland onions, garlics, etc. when the sulfur is used up. Your alliums are what I call virtue plants, the nicer you treat them the better they produce for you, and the more characteristic the flavor of the varieties you grow. So punish your grapes if you like, but baby your garlics and your onions. IMO though you can overdo the sulfur, better to have your soil tested and match the amendments to what you are growing. BTW the sulfur compounds in the harvested bulbs are what makes alliums gassy for a lot of folks! In extreme cases it can "flavor" both breath and sweat unfavorably.

Thanks OldDutch.....I have done a soil test on my compost and have heard that a reading of over 40 kg ha of sulphur is good....also read that my composted horse manure (we run a boarding stable) may be high in sulphur.....Ron England, author of Growing Great Garlic, suggests that garlic first appeared on the scant desert like soils of the Silk Route where it would have struggled to survive........thanks again for your help with garlic flavor

Normally folks don't much have to worry about the sulfur. Calcium is a more common concern, but that is more likely to show up as blossom end rot in tomatoes and peppers. With your manure, nitrogen is not likely to be an issue either, except for side dressing. If your compost is hot enough to kill the weed seeds, you can mulch with that and eliminate a lot of your hand weeding as well.

Soil tests are always a good idea.