by that logic, everyone in the "old world" would have stopped farming in 1100/1500. Until about 1870 it wasn't possible to "intensively" farm land. Intensive r

by that logic, everyone in the "old world" would have stopped farming in 1100/1500. Until about 1870 it wasn't possible to "intensively" farm land. Intensive requires mechanisation. Practically that requires internal combustion engines. Intensive farming started when tractors became cheap enough for everyone to use. As soon as it was practical to plough hundreds of acres in a day, thats when "intensive" was a thing. In the US thats roughly the 20s. The second revolution was cheap pesticides with short half-lives. That was Glyphosate in the 70s.