I haven't seen a truly scientific research on Korean Natural Farming practices. There are some PP slides on the net of a comparison between
permaculture and KNF but doesn't go into details.
This is what I think:
Continues cultivation of the same piece of
land reduces bio-diversity. Minerals deplete, soil structure changes, diseases may build up. When you continuously harvest food, things will deplete in that soil.
So we have to kick start this soil after sometime to replenish its resources and micro-organisms.
There are ways of doing this and Korean Natural Farming is one of them. Like you would inoculate your
milk to make yogurt, you need to inoculate your soil from a wild source so that balance can be restored.
You may also opt for biodynamics and prepare a kick-ass
compost on the side to spread on your cultivated soil from time to time.
You may do bio-intensive and double dig the trenches spreading some good compost in between.
You may do large scale worm composting and use this on your soil.
You may do back-to-eden
gardening and use only woodchips.
You may follow a strict crop rotation scheme and grow green manure in between to replenish the organic matter.
You may grow your mulch and use this on your soil.
Possibilities are endless.
As Dr. Redhawk said before (on another
thread), the gardening style is only a blue print. It gives you a periodic way of dealing with garden chores. They are not silver bullet to cure all gardening problems. Just implement some method and see the difference to make a decision on pursuing that method or not. It may suit you or not.
For example, I can find free
coffee ground and ocean caught fish carcass here easily. I prepare enormous amounts of fish hydrolysate with kefir and my entire garden filled with coffee grounds. When I put these two together, temp reaches to 50 degrees Celsius. It would be silly not to use them.
I stopped looking for evidence if this work or that doesn't. I do things; if they work in my garden and suits to my busy life; I continue to do them. Otherwise I change the way.