Hey Underground, missed this post too, been tapping into the Panama a bit much
It's a common soil mix you can get up here, usually a mix of loam/top soil, peat, and compost. I get some locally at a gardening centre that they add sheep manure when it's available. I cut that about 50/50 with Pro-Mix, creates a nice medium for running in those fabric pots. Fills the pots top to bottom with roots, does't need a lot of feed, I run ~400-450 ppm A&B, every other or 3rd watering depending on the stage. Up here you can buy that tripe mix in bags or by the yard at gardening centres, it's pretty common.