For persia it is 1 extra turn on the worker, 2 extra turn to get to the irrigated corn, 2 turn extra to improve the other corn, that is -14 food already... When will the cow catch up? By turn 50? By turn 100? It certainly isn't soon.
For zulu on quick speed it is 7 vs 5 turns to grow to size 2, then it is 3 turns invested for near corn and for plains hill before the worker can be whipped(we will have BW within 8 turns right?). Then it is 1 turn to move from the plains hill to the irrigated corn (if we do move obviously improve cancle -> move), so it is 2 turns slower to start growing(-6 food) and then 3 turns slower to improve the corn(-9 food), then 2 turns slower to size 2(-2) and 3 turns slower to improve the other food(-4 food) for a total of -21 food for settling on the plains hill (in return for a bit of hammers and a tiny bit of commerce).