What kind of soil did the Greeks farm in? I'm assuming that it was the lighter, higher soil that Roman civilizations favored. There was a lot of resistance to the heavy iron plowing techniques which unlocked the potential of the fertile, lower regions. While of course even a light, iron plow would increase farming efficiency it wouldn't do too much if the animals weren't shod and they were still farming in poor soil. The slave based economies of many ancient civilizations discouraged this development.