The exodus of persons of ALL ethnicities has been going on virtually unabated for the past century, not just blacks. Almost always it was for economic reasons, for black as well as the vastly greater number of all other ethnic groups. Trying to wrest a living from the soil, when you have to buy everything retail and sell everything at wholesale, is not a recipe for quick return, and most of the youth look at this lopsided economic equation, finally deciding that life on the farm is not for them.
Nobody was “expelled” from the land. They fled for greener pastures, lured by promise of much greater remuneration for much shorter hours.
Yes, but additionally, actual innovation occurred over the last century that hardly anyone is working agri now. Only a few people are needed to provide massive amounts of plenty.
That is technology. Some ended up Big Farm, but either way, technology reduced how many people even have to OWN a farm to “sustain” the economy/needs, much less work it.