Wow, what an interesting thread. I won't repeat what's already been said, because others have already given such excellent answers.
I do know this, as far as "real" tractors here in the California Central Valley, the giant agribusiness farms have had soil scientists analyze every square foot of these 10,000 acre plots and log the pH, nutrients, and mineral composition in complex programs. When fertilizing with the behemoth machines these corporations can afford, a GPS system tells the on-board computer exactly where the tractor is and the computer custom mixes the exact requirements of Phosphorus, Nitrogen, Potassium, etc. that that specific few square feet needs. The mixture is constantly changed as the tractor moves. I don't know whether that qualifies as yuppie, real, both, neither, or something else.
BTW, isn't that Eddie Albert's character from "Green Acres" on that old steel wheeled tractor? Real tractor, wannabe "yuppie" gentleman farmer?