I live on high alkaline soils as well. I tried using ironite the first few years I was here to fight chlorosis in some willow trees.

I was never very impressed with the cost-benefit ratio. Started looking into it a bit, and the professionals use a chelated iron spray - far more effective. They use this stuff on stadium fields as well to get that really deep green.

I dunno about the magnesium. It couldn't hurt.....

But I have started using Azomite, a combination of all kinds of trace minerals including Iron and Mg that, theoretically, should make a difference in leached out soils. [after dumping umpty acre feet of irrigation water on my property, I could reasonably conclude I might be a candidate].

I've added it to my vegetable beds and containers.

Here is a link that might be useful: link to azomite info

I don't care for Ironite at all. Here's what to look for in a micronutrient supplement:

water soluble zinc (either zinc sulfate or chelated zinc- make sure it's water soluble though)

manganese should be sprayed on foliage, not applied to the soil because it gets bound by alkaline soils. This applies to chelated or manganese sulfates.

iron chelate EDDHA is the most useful iron for alkaline soils. BUT, it's expensive!! You don't need to use a lot, however.

Good luck!

Iron sulfate is good for bringing the pH down. I use it on my blueberry and magnolia plants that need acid soil.