frikk said:

I would like to know why the food production value decreases. When I have upgraded food production in the academy to level 80, and two farms are upgraded past level 20, why does the food production value still go down? Yes, food consumption will go up and down, according to the troops you have etc., but food production is a function of the work (and money) that a player has put into the game. Surely, this is not fair to players. Is this a rip-off by our game designers? We have paid for it, in good faith, after all.

When it comes to grain, all you need do is substitute the word "production" with "available for storage after consumption"  and it all becomes clear!

There is no rip-off involved, just slightly misleading (for homogeneousness, I assume) wording..  

Yes, the temple of Demeter is the first and most important building to upgrade.

As even with full upgrades...

:p