the idea is that in civ there should be some cities that devote entirely to food production, some as hammer production (:crazyeye:), some as commerce and some just specialists cities. This promote specialization, which is very reflective of the real world.

My suggestion only takes a bit micromanagement.

The way it works is that first, cities must be connected, and each must have a market. Farm City 1 has 6 surplus food each turn, and it sends 4/turn to the "national market" (the capital, or a small wonder perhaps). Then you go to production city 1 and have it take 3 food/turn from this "national market". The 1 extra food just sits there in the "national market" by default will be consume by that city.

If you happen to establish a trade route with neighbors, then you can trade that 1 food/turn with your neighbors for gold. They can allocate that to their cities.

Of course, what is the catch? You pay slightly more maintenance in cities that consume the food. The rate of maintenance goes up exponentially for consuming more food from other cities (especially from foreign cities). This is sort of like the corporation maintenance.