Hi Robert.

I see - you don't need to keep plants away from soil or policemen,
but you need to be thrifty with water. And from what I recall,
Oz has a lot of insects that will eat anything (even floor coverings!)

It is (largely) a desert environment. The middle east has similar
problems: even if you do apply loads of water it might flush buried salt
into the topsoil, poisoning it.

What is your food crop/environment?
You might have a good market for a PIC that can keep a greenhouse
optimal for different veggies, fruit, etc.
If you had a few high-value plants, a PIC might monitor each one.
If doing away with soil completely, it might also be used to
monitor/control the nutrient level.