Yes it is incredible how yields are now so high, of many crops. The increases are not due only to artificial fertiliser, some is animal and plant breeding, some is the power of machinery. Nobody knows how sustainable it all is, and how nutritious some of the food is, but it works for now.
Likewise it means there is plenty of manure around, in many places, if you want a plot to be highly productive.
Or you could be less intensive with green manures, as explained in this forum by Pete Budd.
I should love some volcanic soil!