Improving acidic soil (clay under heavy mulch)

rogerwilco starts with ...
Hello! I need a little guidance and hoping to get some here.

The property we now live on has 30 years of growing behind it, and a great number of mature fruit trees. 2 lemons, peach, fig, persimmon, mandarin, orange, loquat...

We're garden newbies, and the learning curve is quite steep.

We've been here less than a year, and have done our best, but observing a few problems this Spring.

During autumn, we prepared the soil by removing all unwanted plants and weeds, digging in sheep manure, compost and gypsum, and topping off with a heavy layer of euchi mulch.

Check out the pics though!
There's clearly deficiencies in the lemon and camelia. One looks like chlorosis and the other looks like magnesium deficiency. Less sure about the camelia, but it's definitely browning.

So I tested Ph. The soil is quite dramatically acidic. The lemon beds are about 4.5 and the camelia around 5.

So, I presume these deficiencies are caused by low Ph, which is making the trace elements unavailable to the plant.

Now I just need to know how to remedy.

Do I simply peel back the mulch layer, add more organic material (manure, compost, etc.) and a big hit of dolomite limestone before digging it all in, and recovering with mulch?

That's potentially a lot of work, and... it's tricky to dig in around the drip line of mature trees with shallow root plate.

Is there an easier way?!

Thanks for reading, and really appreciate any help you can offer a garden newbie!

Pictures - Click to enlarge
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Julie says...
Dolomite will help to make the soil more alkaline, but is a bit slow to show results. In the meantime, while waiting for it to lower the pH, if you have a wood fired heater, the ashes are excellent for this.

Not sure about adding Epsom salts at this stage, as dolomite already has magnesium, and you could possibly overdo it.