Grafting fruit cuttings onto nitrogen fixing trees

Geoff Lawton mentions that when starting a food forest you should plant about 90% pioneer, n-fixing and support species with about 10% food species. But what about planting 100% support species and from there once the soil is sufficiently replenished the roots would already established. After that you would chop and drop  or coppice then you would graft on any fruit, nut or medicine trees to an already established rootstock. plus i would reason that the roots of any leguminous trees would feed the the fruit nitrogen. Is this reasonable I am speculating for a food forest I want to experiment with starting this winter. this will be my first attempt at a food forest well so any knowledge helps

Not all fruiting stock is compatible to graft onto just any root stock.  

Fruit breeders/hybrid specialists have been trying this for many many years.  It's a bit like trying to graft an elephant's trunk onto a horse.  It would be cool if it worked, but there are incompatibilities that, as yet, haven't been overcome.

I would have figured it would be more simple because of fruit salad trees where theres 5 fruits in one tree. but is there any nitrogen fixing tree that would take to a fruit tree

Not trees, but nitrogen fixing corn has gained some attention.

https://news.wisc.edu/corn-that-acquires-its-own-nitrogen-identified-reducing-need-for-fertilizer/

GMO scientists are probably hard at work splicing this trait into commercial varieties.

Gray Henon wrote:Not trees, but nitrogen fixing corn has gained some attention.

https://news.wisc.edu/corn-that-acquires-its-own-nitrogen-identified-reducing-need-for-fertilizer/

GMO scientists are probably hard at work splicing this trait into commercial varieties.

Very interesting. I wonder if these corn varieties would be able to adapt to the dry southwest region. or if they could work in san Diego area