Remember as a young un.living in Cronulla, the soil was ,well let us say nothing more than coloured sand .My old man, loved growng his own vegetables, the soil then was hardly suitable.He dug holes and every item of peelings.rotten fruit, lettuce leaves. tree leaves was put in and covered with a layer of this "dirty" sand.In a matter of years he had the soil full of earthworms.The depth of the good soil was at least 2 foot under he old scale, and he grew potatoes,beans,carrots,lettuce,cabbage,caulies, climbing beans,sweet peas.
Followed the trend, when I moved to Caringbah as an adult.Even to the point and my old man laughed at me,ya'll never grow paw paws in this climate, nor mangos.I did ,and let him know it big time.
In fact highly illegal I found later, but in the 90s,took a few large plastic bags down in my wagon, and went down to Cronulla beach behind the swimming pools, and gathered up a stack of seawood washed in and ready to stink the joint out.I put the stuff on my garden which gave it a fibre and moisture boost and mulch.
Few people these days want to grow anything, living in units is a deterrent, cost of water, yet we throw sh*loads of vegetable/fruits scraps out like there's no tomorrow.