There are easily three major reasons you could find for why the statement in the BBC article (per person, fewer acres are used growing food for a subsistence fa

There are easily three major reasons you could find for why the statement in the BBC article (per person, fewer acres are used growing food for a subsistence farmer than a city-dweller): 1. Diet (subsistence farmers probably eat less meat, beef in particular; beef has an absurd environment footprint in on basically all metrics). 2. Food waste (the transport of food and delay between production and consumption of food is a major source of food waste; food doesn't spoil in the grocery store waiting to be bought if it is never in a grocery store). 3. Better per-acre yield (which would be surprising, given that for major crops, per-acre yields increased by 3-10x over the last century of industrial farming). I'm saying I don't think 3 is the case at all, and that mostly 1 and maybe 2 explain the difference adequately.