Why did my Hourly Food Production decrease?
If you have noticed a substantial decrease in your hourly Food production rate, it is because you have recently completed training Troops.
Once Troops have completed their training and have been added to your Regiment, they will require an hourly upkeep of Food. This information is viewable by hovering your mouse over your Food reserves listed in the upper right-hand corner of the game screen.
You can also view the Food Consumption rate of each Troop before training. This information is listed in Troop statistics section after you've selected your Garrison and clicked the specific Troop "Train" button.
For example, each Longbowman unit trained will require 9 Food.
Is it possible to acquire a negative Food production rate?
Depending on the type and amount of troops trained, it is possible that your Food production will be negative. Please note that your troops will not abandon your City because of a negative Food production rate.
You are capable of building, researching, and training Troops with a negative Food production rate by employing a few simple tactics.