Originally Posted by oregon aqua
Wetting agents are used more in desert areas where water is more short supply.
This pretty much describes the whole of Australia
Some of the chemicals readily available here seem to vary. This, I assume, is because what is sold is what is produced locally. The dolomite sold here does look different to what is shown in the wikipedia entry but it is the only thing available as far as I'm aware. It should still be mostly calcium magnesium carbonate.
I found some plain soil without the additives and I'm going to try this using what I can get my hands on. I don't see why some substitution would be a problem. The original recipe doesn't exactly call for you to pull out the scales and precisely weigh everything.