Nice article Sarah. The secret to soil fertility is animals manure and lots of it. If we became strictly non meat eating serious consequences would definitely form. The problem is that with tilling required for today's annual plants comes soil erosion and depletion. We need cover crop strategies that include a diverse animal population feeding on them with crop rotation heavily in the mix. It takes thousands of years to build soil which can be depleted in a generation or less. And soil depletion is a root cause in the fall of civilizations.