Dolomite lime is used to sweeten the soil i.e. to increase ph levels. It also has calcium in it which ordinary garden lime doesn't. Stone fruits such as peaches and nectarines utilise the calcium to put energy into making the stone/pit. It is also used on figs as they like a sweeter soil and devote loads of energy into producing fruit. I'll leave other possible applications to the others on this forum.

The following link gives a fairly detailed explanation on how acidification of the soil causes an uptake of aluminium ions, which displace Ca, Mg, and K ions needed by plants.
Some plants are far more tolerant of acidic conditions, and infact require such conditions. Others are not.
I heavily lime my iris beds every year, as I have heavy clay loam. I also add gypsum when remaking them.
Garden lime of course is mostly calcium. Dolomite however also has magnesium, which is probably what Pepino means.
You need to firstly test your soil to see if it is alkaline or acid, and then determine what type of soil your plants like. It doesn't have to be all or none. Treat different areas according to what you are trying to grow there, and group plants according to soil type.

Here is a link that might be useful: Effect of liming soil

Quite correct Jan. Not sure what I was thinking. Lime is basically Calcium. Dolomitic Lime has Magnesium. I'll have to remember to sprinkle some around the Irises you sent me.

Thank you both for informative and clear reply.
Do you think dolomite would be of any use to my tastless grapes problem.
Would an example regarding the use of dolomite be, irises love it but azaleas don't.

Yes nemo. Azaleas don't like alkaline conditions, and bearded irises do. Not ALL irises though. There are many irises that prefer acidic soil conditions, and some that aren't even fussy.
Cheers, Jan

Its worth pointing out that what is sold as Dolomite lime is actually powdered dolomite rock with no heat treatment, therefore it is only neutral to very mildly alkaline. Dolomite will shift soil pH from acid to neutral, or from neutral to slightly alkaline, but not alkaline. For that you require slaked lime, which has been roasted at high temperature to drive off the acid carbon dioxide and leave the basic Calcium oxide. This is sold as builders lime, because when mixed into a paste it reabsorbs CO2 from the air and slowly sets to form limestone once more.

In many case dolomite is added to soil to provide magnesium to plants. Magnesium is an essential trace element, the chlorophyll molecule is based around a central magnesium atom.

Once applying Dolomite, can seedling be planted straight away? If not how long before seedlings can be planted? The seedlings are brocolli and cauliflour.