Natural nitrogen replenishment rate is microscopic. And it will do absolutely nothing about phosphate depletion.
Phosphate replenishment can be done by spreading manure or using fertilizers. It's a harder problem, but you have to work the problem.
Yes, and and the rate of replenishment, even if you dump many times more soy straw on the fields than you will harvest, will still be microscopic.
It plainly doesn't work for anybody, but people who only farm for themselves. It's a grandly inefficient use of a scarce resource — land.
Even if the soil will be squirming with nitrogen fixing organisms, and nothing else for many years, it's nitrogen intake will be like a single nitrate application, or less.
> Phosphate replenishment can be done by spreading manure
And catch god knows how much food borne diseases in the process. That's disgusting, and absurd in the 21st century.
Source: grew up in the sticks and worked on the family farm as a kid.