Where I live in front of my house, there was a
lawn, and beneath this lawn, was gravel, sand and the old soil existing there (but the gravel was brought during construction of the house). This is where I test my
permaculture.
I haven't inputed any organic matter other than the one growing picking fallen leaves from poplar
trees 10 meters away, and lupins growing within those 10 meters, and of course my own kitchen
compost.
Initially nothing could be grown on that soil other then grass. But now the vegetables are growing better, because I improved the soil. I will avoid now disturbing that created soil and not dig further, and only add further organic matter (leaves, lupins, compost) as mulching.
The soil is probably still acidic, but many vegetables grow well: salads, carrots, squash, potatoes, celery, but the broccoli are still rather small. However you can feel the fertility and it is a natural one.
I also grow many flowers and green manures across my lawn, which I cut and mulch. That is excellent organic matter for the garden. And all the remaining green non edible parts of some vegs, like potatoes tops, etc... Somehow I leave the weeds, which are mainly
dandelions and sorrels to cut and mulch as well (and eat them sometimes).
I completely see the value of animal life: worms, birds pooping here and there, increasing its fertility, and also from nearby trees which shed their leaves and create humus in topsoil. That's where I see the cycle of nutrients closing. Well, this is my own
experience. Of course I could have had brought animal manure, rock phosphate and force my soil to produce much more to
feed me, but so far I have eaten little from my garden. The climate is also pretty cold. We already had a blizzard yesterday. But I still have nice broad beans, carrots, swedes and rye growing very happily in there.
Our projects:
in Portugal, sheltered terraces facing eastwards, high water table, uphill original forest of pines, oaks and chestnuts. 2000m2
in Iceland: converted flat lawn, compacted poor soil, cold, windy, humid climate, cold, short summer. 50m2