TrueDat...even 'years ago'(1930's) there was monoculturing, chemical fertilizers and '-cides', over-tilling and bare fields in off season...all that is the opposite of permaculture.I think there is a big difference between the family farm of years ago and the agribusiness "farmers" we have today. Where I grew up, farming means growing one crop - beets - and nothing else.
Even way before the 1930 dust bowl era and mechanization,
farmers were damaging/decimating the land when growing food to the point nothing would grow there. Check out 'Desertification' and how it can be reversed.
Great book about it, a long wide overview, is 'The Soil Will Save Us' by Kristin Ohlson.