Bertolt Stanish

If you control the area with grass, then arguably yes you are robbing the soil below the grass to enrich that in your garden. Lawns are generally just awful for the soil, and if you aren't bound by local laws or regulations, the pure permaculture choice would probably involve reducing its size or converting the lawn altogether. As far as wastes from incredibly wasteful practices outside of your control, yes those are all fair game if you are using them to set up stable systems. David Holmgren talks about this in his book Permaculture: Principles and Pathways. Basically he argues that using non-renewable resources is usually acceptable if the result is renewable systems. The most shocking of example is perhaps using bulldozers to set up ponds and water catchment, much of which can last centuries if left alone, so it's almost certainly worth it given the soil you are generating and the carbon you are capturing in the long run. But if everyone, or even a small fraction of people, started doing permaculture, many of those non-renewable resources would dry up pretty quick, so the more endogenous soil renewal techniques we can develop/learn, the better. Hope that helps you answer your question!

I've been messing around with burying my un-composted food waste beneath my lawn, but on contour--a kind of slow swale. So every time my compost fills up I'll combine it with mail shreddings 1 to 1, run outside, gently pull back a 6-8" deep by 3' section of sod on contour, bury the compost along the section, then replace the sod and squish it down a bit until it is relatively unnoticeable. The effect is like that of a minor swale, particularly as the length of the compost across the contour increases over time. At first it looks like your lawn is bloated, but later it shrinks as it slowly releases nutrients down the landscape. I think pulling the sod back downhill is preferable, as the opening/ridge created is infiltrating the water, not merely directing it slightly upwards over the surface. Not only does this improve your water situation and soil OM, but also saves you from having to compost if you don't like the whole pile/turn chore. It is a bit of task to dig (and kind of evokes embarrassment if you live in an HOA suburb with nosy people breathing down your neck at everything you do), but I really like the idea and I'm going to keep trying to make it easier and less noticeable. Has anyone else tried something like this?